bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of genetic variants of phosphodiesterase 11A in acromegalic patients
Authors: Peverelli E , Ermetici F , Filopanti M , Elli F M , Ronchi C L , Mantovani G , Ferrero S , Bosari S , Beck-Peccoz P , Lania A , Spada A
Published: August 2009

Objectives

Aberrant cAMP signaling is involved in the pathogenesis of somatotropinomas. The aim of the study was to screen acromegalic patients for the presence of variants of phosphodiesterase type 11A (PDE11A) gene, which have been recently identified in adrenocortical and testicular tumors.

Subjects and methods

We sequenced the PDE11A gene-coding region in 78 acromegalic patients and 110 controls. Immunohistochemistry for PDE11A was performed in a subgroup of adenomas and normal pituitary samples.

Results

We found 15 nonsynonymous germline substitutions in 13 acromegalic patients (17%), i.e. 14 missense variants (Y727C in six, R804H in one, R867G in four, and M878V in three) and one truncating mutation (FS41X), with a prevalence only slightly higher than that observed in controls (14%). Immunohistochemistry revealed PDE11A expression higher in somatotropinomas than in normal somatotrophs, without significant difference between tumors with or without PDE11A variants, with the exception of two tumors (one with loss of heterozygosity (LOH) at the PDE11A locus and one with FS41X mutation) showing markedly reduced PDE11A staining. No significant differences in hormonal and clinical parameters between patients with or without PDE11A variants were observed, although patients with PDE11A changes showed a tendency to have a more aggressive tumor compared with patients with wild-type sequence (extrasellar extension in 69 vs 45%).

Conclusions

This study first demonstrated the presence of PDE11A variants in a subset of acromegalic patients, which was only slightly more frequent than in controls. The normal expression of the enzyme in the majority of tumor tissues together with the lack of significant clinical phenotype suggests that these variants might only marginally contribute to the development of somatotropinomas.
Mega‐Environment Identification for Barley Based on Twenty‐Seven Years of Global Grain Yield Data
Authors: Hernandez‐Segundo Eduardo , Capettini Flavio , Trethowan Richard , van Ginkel Maarten , Mejia Apolinar , Carballo Aquiles , Crossa Jose , Vargas Mateo , Balbuena‐Melgarejo Artemio
Published: August 2009

Knowledge of target environments in breeding programs is important to better direct the development of germplasm. The objectives of this study were to identify associations among barley (Hordeum vulgareL.) growing environments to identify mega‐environments to select the best locations to breed barley. Twenty‐seven years of grain yield data from the International Barley Yield Trial (IBYT) conducted by the ICARDA‐CIMMYT Barley Breeding Program, consisting of 750 grain yield trials of two replications representing 235 locations in 75 countries, were analyzed using pattern analysis to group sites across years that represent similar selection environments. The shifted multiplicative model (SHMM) was employed to group sites within each year. Environments clustered into three main groups and squared Euclidean distances were used to identify a representative location within each cluster. Group 1 locations were characterized as being cool with intermediate precipitation; Group 2 locations were warmer and drier; and Group 3 sites were generally cool and had the highest average precipitation. The respective representative key locations for each of the three groups were Leida, Spain; Boulifa, Tunisia; and Setif, Algeria. All three key locations are located in the Northern Hemisphere between 36° and 41° latitude. The results of this study show that the global adaptation of barley is possible and can be improved by breeding and selection for adaptation within the three main mega‐environments identified.
Efficacy of Antioxidant Overproduction on Fiber Growth and Maturation in Cotton
Authors: Gottula John , Price Kermit , Allen Randy D. , Mullinix Ben , Wright Robert J.
Published: August 2009

Electron transport in plant cells inevitably results in the creation of reactive oxygen species (ROS) that can hinder metabolic processes and cause cellular damage. In spite of the gains additional antioxidants may impart to the cotton (Gossypium hirsutum L.) photosynthetic apparatus, single time point measurements on live plants have not reflected distinguishable phenotypes for key physiological measures. Transgene efficacy may also be quantified by measuring cumulative agronomic performance (lint yield and quality) under conditions that promote photorespiration and ROS production. To test this hypothesis, cotton lines constitutively expressing the ascorbate peroxidase (APX) or glutathione reductase (GR) protein were examined in field trials (2005, 2006, and 2007) under three different irrigation treatments. Yield, gin turnout, and 23 measures of fiber quality were assessed. Transgene (APX and GR) efficacy and in vitro culture effects were estimated by comparing a line's performance with the null and wild‐type checks based on an analysis of variance using a linear mixed model to estimate general least squares and variance components. Significant effects were observed in 18 traits. Despite no significant changes in fiber maturity, all GR and APX transgenic lines produced significantly finer fibers than the wild‐type. Fiber maturity is a problem in western Texas that affects most fiber quality measures especially the fineness measurement micronaire.
Response of Yield Heterosis to Increasing Plant Density in Maize
Authors: Liu Weidong , Tollenaar Matthijs
Published: August 2009

Genetic yield improvement in maize (Zea mays L.) has been associated with heterosis and increased tolerance to high plant densities, but the physiological processes underlying heterosis for tolerance to plant density stress have not been identified. The objective of this study was to quantify the response of heterosis for grain yield to increasing plant density, and to examine the processes underlying this response. Field experiments were conducted in Ontario, Canada, during the 2005 and 2006 growing seasons in which the hybrid CG60 × MBS1236 and its parental inbred lines were grown at a low plant density (4 plants m−2), a high plant density (12 plants m−2), and a plant density resulting in an approximately equal leaf area index (LAI) for all three genotypes. Increasing plant density from 4 to 12 plants m−2 resulted in an increase in heterosis for grain yield and harvest index (HI), but did not affect heterosis for dry matter at maturity. Heterosis for dry matter accumulation did not differ between the low and the high plant density treatment, increased from the presilking to the postsilking period, and was only to a small extent attributable to a higher maximum LAI and light interception by the hybrid as compared to its parental inbred lines. Increased heterosis for HI was associated with a greater plant‐to‐plant variability and a higher threshold plant dry matter for HI at maturity in the inbred lines as compared to the hybrid.
Impact of Heterozygosity and Heterogeneity on Cotton Lint Yield Stability
Authors: Cole C. B. , Bowman D. T. , Bourland F. M. , Caldwell W. D. , Campbell B. T. , Fraser D. E. , Weaver D. B.
Published: August 2009

In the last 8 yr, cotton (Gossypium hirsutum L.) growers in North Carolina have experienced variations in the year‐to‐year lint yield averages that range from a 56% increase to a 49% decrease. This variability results in wild fluctuations in income and a desire for more stable yields. Genetic structure may contribute to stability. This study was conducted to determine the impact of heterozygosity and heterogeneity on lint yield stability. Lint yield was observed in 18 environments over 3 yr among four population types that included homozygous lines grown in pure stands, homozygous lines grown in blended stands, hybrids grown in pure stands, and hybrids grown in blended stands. Comparisons were made using trait means, standard deviations, and the coefficients of variation (CVs) calculated over environments. There was no significant difference between lines grown in pure stands and blended lines with respect to yield or stability. Hybrids had a lower CV (were more stable) than homozygous lines. This stability was attributed to the hybrids and blends of hybrids out‐yielding the homozygous lines and blends of homozygous lines in the low‐yielding environments, but having similar yields in the high‐yielding environments. These results do not support growing blends to increase stability or yield; however, growing hybrid cultivars could result in increased yields while reducing variability compared with current production practices.
Soil Water Repellency Development in Amended Sand Rootzones
Authors: Moody David R. , Schlossberg Maxim J. , Archibald Douglas D. , McNitt Andrew S. , Fidanza Michael A.
Published: August 2009

Particulate organic matter (OM) and surface area–limited sands are associated with soil water repellency (SWR) in turfgrass systems. The increasing ubiquity of amended sand rootzones warrants investigation of factors contributing to SWR. Our objective was to identify how amendment type and/or inclusion rate affect rootzone SWR over a range of irrigation regimes. A U.S. Golf Association–specified sand was amended with dried turfgrass roots and either sphagnum peat moss (SPM), reed sedge peat (RSP), biosolid compost (BSC), or calcined clay (CC) at 0, 0.1, or 0.2 m3 m−3 Mixes were saturated, gravitationally drained, incubated under isothermal ventilation having mean vapor pressures of 1.78, 2.19, or 2.45 kPa, and reirrigated when matric tension exceeded 300 kPa. After 138 d, rootzone subsamples were eluted of particulate OM before measuring mineral‐adsorbed hydrocarbon content (MAHC) by infrared spectroscopy. The repellency index was used to quantify SWR of intact (Rintact) and eluted (Reluted) samples. Amendment rate (0.2 > 0.1 > 0 m3 m−3) and type (BSC > RSP = SPM > CC) significantly affected Rintact Only CC‐amended rootzones were more wettable than the control. Severely elevated Reluted and MAHC were observed in all sands amended by BSC. Inclusion of SPM or RSP at 0.1 m3 m−3 resulted in Reluted and MAHC values statistically equivalent to the control rootzone. At 0.2 m3 m−3 inclusion, all organic amendments significantly increased Reluted and MAHC relative to the control (BSC > RSP = SPM).
Impact of Biosolids on Hormone Metabolism in Drought‐Stressed Tall Fescue
Authors: Zhang Xunzhong , Ervin E.H. , Evanylo G.K. , Haering K.C.
Published: August 2009

The presence of biologically active substances (BAS) in biosolids may enhance plant stress tolerance and growth, but the underlying mechanisms are not well understood. This greenhouse study investigated the effects of untreated biosolids, containing 2.1 μg indole‐3‐acetic acid (IAA) g−1, and tryptophan‐treated biosolids, containing 15.4 μg IAA g−1, on tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] drought resistance. Treatments included a fertilizer control, indole‐3‐butyric acid (IBA) at 2 μM (hormone control), treated biosolids (2.95 g kg−1 soil), and untreated biosolids (2.97 g kg−1 soil). Nitrogen availability was equalized among treatments, and tall fescue physiological responses were measured under well‐watered or moisture stress conditions. Treated biosolids improved turfgrass quality and root mass under both soil moisture regimes and delayed leaf wilting under moisture stress. At the end of the second drought cycle (2 February), treated biosolids improved quality and photochemical efficiency by 18 and 26% relative to the control. Treated biosolids increased leaf IAA by 122 and 52%, respectively, and trans‐zeatin riboside by 100 and 189%, respectively, during each of two maximum drought periods. Leaf tissue increases of IAA and cytokinin were associated with greater content of these hormones in the soil. The data suggest that biosolids application may alter growth hormone (IAA and cytokinin) content and improve plant drought resistance.
Imazamox Tolerance in Mutation‐Derived Lines of Upland Cotton
Authors: Bechere Efrem , Auld Dick L. , Dotray Peter A. , Gilbert Lyndell V. , Kebede Hirut
Published: August 2009

Induction of genes conferring herbicide resistance by mutagenesis could facilitate use of imidazolinone herbicides in upland cotton (Gossypium hirsutum L.). In 1997 and 1998, seeds of eight High Plains cotton cultivars were treated with 2.45% v/v ethyl methanesulfonate. The resulting M3 and M4 generations were sprayed with imazethapyr, and the M5 and M6 generations were sprayed with imazamox. Four stable M6 to M7 lines with tolerance to imazamox were identified in 2004. During 2005 and 2006, tolerant mutants and their nonmutated parents were treated at the four‐leaf stage with topical applications of imazamox applied at five rates (0, 88, 175, 350, and 700 g a.i. ha−1). Elevated levels of tolerance to imazamox were observed in all mutants. Imazamox did not impact fiber length. Preliminary investigation indicated that tolerance to imazamox was controlled by a partially dominant single gene. An allelism test revealed that the tolerance genes in the four mutants are either alleles in the same locus or are very tightly linked.
A Target Region Amplified Polymorphism Marker for Fertility Restorer Gene Rf1 and Chromosomal Localization of Rf1 and Rf2 in Cotton
Authors: Wang Fei , Yue Bing , Hu Jinguo , Stewart J. McD. , Zhang Jinfa
Published: August 2009

Cytoplasmic male sterility (CMS), a maternally inherited trait characterized as an inability to produce functional pollen, is an important biological system for economically producing hybrid seed to enhance crop yield and studying cytoplasmic and nuclear gene interactions. In cultivated tetraploid cotton (Gossypium hirsutum L.), male fertility in two systems CMS‐D2 and CMS‐D8 is restored by two restorer genes Rf1 and Rf2, respectively. The objectives of the present study were to identify additional molecular markers for the two restorer genes and to determine their chromosomal location in the cotton genome. Two backcross (BC1F1) populations were developed with D2 and D8 restorers containing their respective cytoplasms as female in crosses with the same Upland cotton maintainer as male and recurrent parent. One pentatricopeptide repeat (PPR)–based target region amplified polymorphism (TRAP) marker was developed to be tightly linked to the Rf1 gene with a genetic distance of 0.8 cM, while three more simple sequence repeat (SSR) markers (NAU2232‐550/650, NAU2232‐750/850, and NAU 2801‐250) were identified to be closely linked to Rf2 Using two common SSR markers, a consensus linkage group was constructed to include both Rf1 and Rf2 loci that were anchored in a 14.0‐cM region by the two PPR gene‐based markers. Based on four chromosome‐anchored SSR markers, Rf1 and Rf2 were localized on chromosome D5 within a genetic distance of 1.4 cM, providing an incentive for further investigations of this Rf1/Rf2–containing region.
Associations among Lint Yield, Yield Components, and Fiber Properties in an Introgressed Population of Cotton
Authors: Zeng Linghe , Meredith William R.
Published: August 2009

Broadening the genetic base is essential for genetic improvement of lint yield and fiber quality in upland cotton (Gossypium hirsutum L.). An exotic germplasm population derived from multiple crosses between G. barbadense L. and G. hirsutum was obtained from USDA‐ARS at Las Cruces, NM. Experiments were designed to evaluate this germplasm for genotypic variation in lint yield and fiber quality. Two hundred germplasm lines and five cultivars were planted at two locations in 2006 and one location in 2007. Significant (P ≤ 0.001) genotypic variation for yield and fiber quality was identified. In path coefficient analysis, bolls per square meter had the largest direct effect on lint yield, while boll weight and lint percentage had secondary direct effects on yield. Lint yield was negatively associated with fiber quality. Lint per seed was favorably correlated with lint percentage, elongation, span lengths, and fineness. Based on stepwise analysis, 50% length, short fiber content, fineness, maturity ratio, and 2.5% length contributed to strength, in decreasing order of significance. Short fiber content was negatively correlated with fineness (r = −0.41). These results indicate that this germplasm is a useful genetic resource for genetic improvement of lint yield, fiber quality, and analysis of interrelationships between lint yield and fiber quality.
Development of Drought‐Tolerant Canola (Brassica napus L.) through Genetic Modulation of ABA‐mediated Stomatal Responses
Authors: Wan Jiangxin , Griffiths Rebecca , Ying Jifeng , McCourt Peter , Huang Yafan
Published: August 2009

Canola is one of the most important oilseed crops, and its seed yield and quality are significantly affected by environmental stresses such as drought. The phytohormone abscisic acid (ABA) is induced by drought and triggers stomatal closure to reduce transpiration, which accounts for >90% of water loss in plants. The ABA‐mediated stomatal response is a dosage‐dependent process that can be achieved by either increasing the endogenous ABA concentration or by sensitizing the responsiveness of guard cells to the hormone. We summarize the recent breakthroughs in the understanding of key molecular components that regulate the homeostasis and sensing of ABA, and their potential applications in genetic engineering for drought tolerant canola. In particular, the α and β subunits of protein farnesyltransferase have been identified as negative regulators of ABA‐mediated stomatal responses, and their effectiveness as the targets for engineering drought tolerance and yield protection has been confirmed in canola in the field. Further development of the drought stress tolerance property in the crop will likely have a fundamental impact on its productivity in many regions of the world.
Enhanced Tolerance to Multiple Abiotic Stresses in Transgenic Alfalfa Accumulating Trehalose
Authors: Suárez Ramón , Calderón Cecilia , Iturriaga Gabriel
Published: August 2009

Alfalfa (Medicago sativaL.) is an important forage crop in many countries with high biomass production and the third‐most‐cultivated crop in the United States, with high protein content and potential use as biofuel. Here we describe the use of a chimeric translational fusion of yeast trehalose‐6‐phosphate synthase (EC 2.4.1.15) and trehalose‐6‐phosphate phosphatase (EC 3.1.3.12) genes to engineer stress tolerance in alfalfa. The gene fusion was overexpressed using either the constitutive35Spromoter or the stress‐regulatedrd29Apromoter. Transgene insertion in the genome was checked by polymerase chain reaction and transcript expression by reverse transcription polymerase chain reaction. Several independent transgenic plants were selected in the presence of kanamycin and further analyzed. Yeast gene encoding trehalose‐6‐phosphate synthase (TPS1)–yeast gene encoding trehalose‐6‐phosphate phosphatase (TPS2) gene expression under the35Spromoter led to plants with stunted growth and less biomass, whereasTPS1‐TPS2expression driven by therd29Apromoter improved growth and provoked a significant increase in plant biomass at the foliage level in the different transgenic lines. Trehalose accumulated in all the different lines at similar levels under stress conditions. Transgenic plants displayed a significant increase in drought, freezing, salt, and heat tolerance. This is the first time that genetic engineering of trehalose metabolism is reported in alfalfa and demonstrates that it can improve multiple stress protection in this crop. Thus, the yeast TPS‐TPP fusion protein represents a great potential for generating stress‐tolerant crop plants for agriculture.
A Comparison of Mixed‐Model Analyses of the Iowa Crop Performance Test for Corn
Authors: So Yoon‐Sup , Edwards Jode
Published: August 2009

Multienvironment trials generally have highly unbalanced data structures in which a particular cultivar is only observed in a subset of all environments for which data are available. A very common approach to reporting data from such unbalanced data is to subset the data into balanced subsets and restrict comparisons within balanced subsets. Such an approach results in much information being ignored. We undertook an empirical study of 65 individual data sets from the Iowa Crop Performance Test for corn (Zea mays L.) to compare eight different mixed linear models to determine which features in the data need to be considered in developing approaches to make use of all available information. We used a model selection approach to identify the best model based on the presence or absence of heterogeneity of error variances among environments, heterogeneity of genotypic variances among environments, and heterogeneity of genotypic correlations between pairs of environments. The trait analyzed was grain yield. We found evidence of heterogeneity of error variances among locations in 58 of 65 data sets for two model selection criteria. Heterogeneity of genotypic variances and correlations between pairs of environments was found in about half of the sets we analyzed. A general recommendation for model selection cannot be made from this analysis. In general, we found that heterogeneity of variances and correlations was prominent in many data sets. Identification of the best statistical model for a particular data set may be dependent on application of a model selection approach.
Phosphorus Fertility Effects on the Expression of the Low Phytic Acid Barley Phenotype
Authors: Jackson Chad A. , Windes Juliet M. , Bregitzer Phil , Obert Don , Price William , Brown Bradford
Published: August 2009

Low phytic acid (LPA) barley (Hordeum vulgare L.) cultivars partition phosphorus (P) in seed tissue differently than conventional wild‐type (WT) barley cultivars. A reduction in seed phytic acid (myo‐inositol‐1,2,3,4,5,6‐hexkisphosphate) is coupled with an increase in inorganic phosphorus (Pi). The response of the LPA characteristic to phosphate fertilization has not been previously investigated; therefore the effect of phosphate fertility on barley seed yield, and concentrations of seed total P, seed Pi, and flag leaf P was investigated at four locations over two years. The LPA cultivars were hypothesized to behave similarly to WT cultivars, therefore two WT cultivars, Baronesse and Colter, were compared to one LPA cultivar, Herald (lpa1–1 mutation), and one LPA advanced breeding line, 01ID451H (mutation 640). At three locations, phosphate fertilizer (P2O5) was applied in the form of triple superphosphate (0–45–0) at rates of 0, 56, 112, and 168 kg ha−1 Increased P fertilization was associated with increased flag leaf P concentration, but no changes were observed for other measured characteristics. At a fourth location, differential soil P fertility was provided via previously established plots varying from very low to adequate P fertility. Inadequate levels of P were associated with delayed maturity, and reductions in yield, test weight, height, and total seed P concentration. The responses of LPA and WT barleys were similar, indicating the LPA traits in barley originating from the lpa1‐1 and 640 mutations are stable under a wide range of soil P fertility.
Effect of Advanced Cycle Breeding on Genetic Gain and Phenotypic Diversity in Barley Breeding Germplasm
Authors: Condón Federico , Rasmusson Donald C. , Schiefelbein Edward , Velasquez Guillermo , Smith Kevin P.
Published: August 2009

Plant breeding with elite parents within closed populations has proven to be a successful strategy to achieve genetic gains and conserve favorable gene complexes. To investigate the effects of advanced cycle breeding on genetic gain, phenotypic variation, and germplasm differentiation, 15 agronomic and malting quality traits were evaluated for a set 98 genotypes including ancestors, parental founders, and elite breeding lines developed at the University of Minnesota barley (Hordeum vulgare L.) breeding program between 1958 and 1998. The material was evaluated in five trials at three locations in 2002 and 2003. Significant gains were observed for 11 traits during the 40‐yr period of advanced cycle breeding, including yield, lodging, malt extract, and wort beta‐glucan content. In parallel, we observed a change in phenotypic variance for seven traits while eight traits, including yield, showed no change. Of the seven traits that showed a change in variance, five showed a reduction, one increased, and one was variable. There were significant correlations among most of the traits, most likely due to simultaneous selection. A principal component analysis explaining 58.1% of the variation showed differentiation of the most recent breeding lines from the breeding program founders. Retrospective analysis of changes in genetic gain and phenotypic variance can be useful in designing strategies to manage genetic variation for target traits in breeding programs.
Genomewide Selection and Marker‐Assisted Recurrent Selection in Doubled Haploid versus F2 Populations
Authors: Mayor Patricio J. , Bernardo Rex
Published: August 2009

Molecular markers have been previously found useful for increasing genetic gain in maize (Zea mays L.). The use of doubled haploids (DHs) instead of F2 plants (or, equivalently, F3 families) may permit a better estimation of marker–trait associations. Our objective was to determine the usefulness of DH versus F2 populations in marker‐assisted recurrent selection (MARS) and genomewide selection. We simulated testcrosses from a DH population and an F2 population from the same cross between two inbreds and studied genetic models defined by the number of quantitative trait loci (QTL) and trait heritability (H). Equal‐time comparisons of selection response were between Cycle 3 with an F2 population and Cycle 2 with a DH population. For the genetic model of 100 QTL, H = 0.20 and a population size of N = 100, the ratio of response to selection in DH versus F2 populations was RDH:F2 = 109% for genomewide selection and 128% for MARS. For the genetic model of 20 QTL, H = 0.80 and N = 100 these values decreased to 99% for genomewide selection and 109% for MARS. Although genomewide selection was superior to MARS for a given type of population, the advantage of using DH instead of F2 populations was greater in MARS than in genomewide selection. We concluded that DH populations are most useful in genomewide selection and MARS when many QTL control the trait, H is low, and N is small.
Chilling Effects during Maize Tassel Development and the Lack of Compensational Plasticity
Authors: Tranel Dean , Knapp Allen , Perdomo Antonio
Published: August 2009

Stress during tassel formation can reduce tassel size and cause insufficient pollen production in seed production. When stresses affect plant development, component compensation for grain yield is known to occur in some crops. Tassel component compensation for pollen production has not been previously reported. Chilling was imposed on two dent maize (Zea mays L.) inbreds (103 and 113 relative maturity [RM]) at the initiation of tassel formation, a critical period for maximizing pollen production. The 103 RM inbred showed limited response to chilling stress. The 113 RM inbred produced 60% fewer branches resulting in 45% fewer spikelets and 43% fewer pollen grains per tassel when chilling was applied during branch meristem initiation. For the same inbred, 42% fewer spikelets and 29% fewer pollen grains per tassel were produced when chilling was applied during spikelet meristem initiation. Chilling stress during meiosis of microsporogenesis did not decrease pollen production per anther. A decrease in the percentage of starch‐filled pollen grains was found only in the lower florets on the lowest branch. The effect of decreased branch or spikelet production on total pollen production was not compensated by subsequent production of spikelets, florets, anthers, or pollen grains per anther. Susceptibility of pollen production to chilling stress during tassel formation varies among modern dent inbreds, although plasticity in the tassel for pollen yield was not observed.
Development and Characterization of Large‐Scale Simple Sequence Repeats in Jute
Authors: Mir Reyazul R. , Banerjee Sumana , Das Moumita , Gupta Vikrant , Tyagi Akhilesh K. , Sinha Mohit K. , Balyan Harindra S. , Gupta Pushpendra K.
Published: August 2009

Jute is an important crop of the Indian subcontinent and comprises tossa jute (Corchorus olitorius) and white jute (C. capsularis). The yield and fiber quality of this crop remained stagnant for many years and could not be improved through conventional plant breeding. Also, no effort has been made to develop molecular markers on a scale required for marker‐assisted selection (MAS) to supplement conventional plant breeding. As a first step toward deploying MAS for jute improvement, 2469 simple sequence repeats (SSRs) were developed in tossa jute (JRO 524) using four SSR‐enriched genomic libraries. A random subset of 100 SSRs (25 SSRs from each library) was used to detect polymorphism between the parental genotypes of each of the two recombinant inbred line (RIL) mapping populations. The RILs are being developed from JRO 524 × PPO4 (for fiber fineness) and JRC 321 × CMU 010 (for lignin content) crosses to prepare molecular maps and conduct quantitative trait loci (QTL) analyses. Both SSR length polymorphism and ± polymorphism (null alleles, i.e., presence and absence of specific SSR) were detected; 50 SSRs detected polymorphism between the two genotypes of tossa jute, whereas 45 SSRs detected polymorphism between the two genotypes of white jute. This SSR allelic polymorphism in jute is higher than that reported in other crops and is adequate for construction of genetic maps for QTL analysis. The large‐scale SSRs will also prove useful in studying genetic diversity, population structure, and association mapping.
Investigation on Cross‐Compatibility Barriers in the Biofuel Crop Jatropha curcas L. with Wild Jatropha Species
Authors: Kumar R. Senthil , Parthiban K. T. , Hemalatha P. , Kalaiselvi T. , Rao M. Govinda
Published: August 2009

Interspecific hybridization in Jatropha species plays a significant role in crop improvement by transferring useful traits such as yield, high oil content, maximum number of seeds, more femaleness, and hard stems for promoting Jatropha as a biofuel crop. The wide crosses among the species resulted in limited success due to pollen incompatability. Hence, the objective of the study was to assess pre‐ and postzygotic barriers through pollen–pistil interaction between cultivated Jatropha curcas and other three wild Jatropha species. In this study, the cross J. curcas × J. gossypifolia, even though the pollen tubes reached ovaries after pollination, failed to produce seeds, and the cross between J. curcas × J. podagrica indicated incompatibility signs of bulged pollen tubes coupled with reverse direction of pollen tube growth. The interspecific cross of J. curcas with J. villosa showed crossability barriers of crinkled and twisted growth pattern of pollen tubes and failed to reach ovary. In the case of selfing (J. curcas × J. curcas), pollen tubes reached ovary within an hour and produced normal seeds. Reciprocal crosses of these species exhibited successful fertilization of pollen tubes, but seed set was very low or no seed set was noticed.
Elevated Atmospheric Carbon Dioxide and O3 Differentially Alter Nitrogen Acquisition in Peanut
Authors: Tu Cong , Booker Fitzgerald L. , Burkey Kent O. , Hu Shuijin
Published: August 2009

Elevated atmospheric CO2 and ozone (O3) may affect productivity of legumes in part by altering symbiotic N2 fixation. To investigate this possibility, measurements of plant biomass, N levels and natural 15N abundance (δ15N) were used to examine the effects of elevated CO2 and O3 on N acquisition in field‐grown peanut (Arachis hypogaea L.) using open‐top chambers. Seasonal 12‐h daily average CO2 treatment concentrations were 376, 550, and 730 μmol mol−1 Carbon dioxide treatments were applied in reciprocal combinations with seasonal 12‐h daily average O3 concentrations of 21, 49, and 79 nmol mol−1 At mid‐vegetative growth, elevated CO2 significantly reduced leaf N concentrations by up to 44%, but not δ15N values. Elevated O3 did not significantly affect N concentrations or δ15N values. At harvest, plant N concentrations were similar among treatments except for a 14% reduction in the highest‐level CO2–O3 treatment. Plant N accumulation varied in proportion with treatment effects on biomass production, which was increased with elevated CO2 when averaged over the O3 treatments and suppressed by high‐level O3 at ambient CO2 Elevated CO2 reduced plant δ15N values in low‐ and mid‐level O3 treatments while mid‐ and high‐level O3 increased them at ambient CO2 The changes in δ15N values suggested that N2 fixation activity was stimulated with elevated CO2 and inhibited by elevated O3 Elevated CO2 ameliorated detrimental O3 effects to varying extents depending on the concentrations of the two gases. These results indicated that interactions between CO2 and O3 on plant physiology can alter N acquisition processes, with impacts on peanut productivity likely dependent in part on these changes.
QTL Analysis of Seed Iron, Zinc, and Phosphorus Levels in an Andean Bean Population
Authors: Cichy Karen A. , Caldas Gina V. , Snapp Sieglinde S. , Blair Matthew W.
Published: August 2009

Iron and zinc are essential micronutrients for human health often found in insufficient quantities in the diet. Biofortification of seed crops has been undertaken to reduce micronutrient malnutrition. The objectives of this study were to identify variability for seed Fe, Zn, P, and phytic acid levels in an F5:7 recombinant inbred line (RIL) population developed from a cross between AND696 and G19833, both common beans (Phaseolus vulgaris L.) of Andean origin. Quantitative trait loci (QTL) analysis was conducted with data from 2 yr and 2 P treatments with a previously described linkage map of AND696/G19833. Significant environmental and genetic variability for Fe, Zn, and P levels was identified, and Fe and Zn levels were correlated (up to r=0.53). Quantitative trait loci for seed Fe and Zn co‐localized on three linkage groups (B1, B6, and B11). On B6, a QTL for Fe (R2 = 0.36) was found at the same marker interval as a QTL for seed Zn (R2 = 0.39), both derived from AND696. Quantitative trait loci for seed P were identified on six linkage groups and explained 17 to 55% of the total phenotypic variation depending on year and environment.
Determination of Dry Matter Yield from Legume–Grass Swards by Field Spectroscopy
Authors: Biewer Sonja , Fricke Thomas , Wachendorf Michael
Published: August 2009

An efficient and accurate detection of dry matter (DM) yield of legume–grass mixtures can facilitate a targeted and site‐specific management of legume‐based swards. The major objective of this study was to examine the relationship between spectral signatures of legume–grass swards and DM yield across a wide range of legume species (white clover [Trifolium repens L.], red clover [T. pratense L.], alfalfa [Medicago sativa L.], birdsfoot trefoil [Lotus corniculatus L.]), legume proportion (0–100% of DM), and growth stage (beginning of tillering to end of flowering). Modified partial least squares (MPLS) regression, stepwise multiple linear regression (SMLR), and the vegetation indices (VIs), simple ratio, normalized difference vegetation index, enhanced vegetation index, and red edge position were used for analysis of the hyperspectral data set (350–2500 nm). Compared to common calibrations, legume‐specific models achieved better results, indicating that each legume species had its own spectral characteristics. Modified partial least squares and SMLR gave the best R2 values, ranging in cross validation from 0.74 to 0.92 with a standard error below 92 g DM m−2 The DM yield prediction by VIs resulted in unsatisfactory accuracies. Prediction accuracy for MPLS and SMLR models were still acceptable even with a reduced spectral data set (630–1000 nm), a finding that could facilitate an application of field spectroscopy in practice.
Determining the Contribution of Legumes in Legume–Grass Mixtures Using Digital Image Analysis
Authors: Himstedt Maike , Fricke Thomas , Wachendorf Michael
Published: August 2009

Digital image analysis could be a rapid and precise technique for estimating legume proportions in grass swards. In 2004, we conducted a pot study to evaluate a digital image analysis (DIA) system for estimation of legume dry matter (DM) contribution in legume–grass mixtures. Examination of pure swards and binary legume–grass mixtures of red clover (Trifolium pratenseL.), white clover (T. repensL.), alfalfa (Medicago sativaL.), and perennial ryegrass (Lolium perenneL.) took place after 35, 49, and 63 d of growth. To estimate the cover percentage of legumes in the swards, a total of 64 digital pictures were taken. The DM contribution of legumes (% of total biomass) showed a significant relationship with the proportion of image area covered by legumes (% of total area), which was classified visually. A DIA system for grayscale images was developed with the software Optimas. We found that DIA could be used to accurately predict legume contribution in mature swards. Legume contribution, as estimated by DIA, was significantly correlated with DM contribution of red clover (R2= 0.87), white clover (R2= 0.85), and alfalfa (R2= 0.79). Bare ground reduced the predictive ability of DIA in young or open swards. Use of DIA may be limited until we refine the method to deal with bare ground and different leaf shapes associated with various weed species.
Development of Canopy Reflectance Models to Predict Forage Quality of Legume–Grass Mixtures
Authors: Biewer Sonja , Fricke Thomas , Wachendorf Michael
Published: August 2009

Timely assessments of nutritive values of legume‐based swards during the growing season can facilitate a targeted and site‐specific forage management. This study was undertaken to explore the potential of field spectral measurements for a nondestructive prediction of metabolizable energy, ash content, crude protein (CP), and acid detergent fiber of legume–grass mixtures. A population of 200 legume–grass swards (Lolium perenne L., Trifolium repens L., Trifolium pratense L.) representing a wide range of legume proportion (0–100% of dry matter), and growth stages (beginning of tillering to end of flowering) were used in this investigation. The paper examines three techniques for analysis of the hyperspectral data set (350–2500 nm): two‐waveband reflectance ratios, modified partial least squares (MPLS) regression, and stepwise multiple linear regression (SMLR). Forage quality variables had weak relationships with the developed reflectance ratios, whereas hyperspectral analysis by MPLS and SMLR resulted in high precision (0.70 ≤ R2 ≤ 0.94). Even with a reduced spectral data set (630–1000 nm), estimates of MPLS and SMLR models were still acceptable for forage ash (0.62 ≤ R2 ≤ 0.78) and CP (0.83 ≤ R2 ≤ 0.86), a finding that could facilitate an application of field spectroscopy with more simple sensors. Estimates of ash and CP were further improved by legume‐specific calibrations.
Mapping of Quantitative Trait Loci Using a Doubled‐Haploid Population from the Cross ofIndicaandJaponicaCultivars of Rice
Authors: Lapitan Victoria C. , Redoña Edilberto D. , Abe Toshinori , Brar Darshan S.
Published: August 2009

Improving the cooking and eating quality of grain has always been an important consideration in most rice (Oryza sativaL.) breeding programs. In this study, an established rice doubled‐haploid (DH) population consisting of 219 lines from anther culture of the F1 ofindicavariety PSB Rc10 andjaponicavariety Nipponbare was used to identify the quantitative trait loci (QTL) for amylose content (AC), gel consistency (GC), and gelatinization temperature (GT). Two hundred five simple sequence repeat (SSR) markers were used to construct a genetic linkage map covering the 12 chromosomes. A total of 13 QTLs were identified—three for AC and five each for GC and GT. Eight QTLs had major effects from which seven coincided with the most important loci identified in previous reports. All QTLs for AC were shown to have major effects on GC and GT. The QTL with the largest effect, which accounted for 74% of the AC variation corresponded to the waxy (Wx) locus while the other two QTLs were located above and below this region. The significant phenotypic correlations of these traits may underlie the colocalization of their QTLs. A major QTL specifying GT was detected within the alkali degeneration (Alk) locus. Other minor QTLs were identified for GC in chromosomes 2 and 8 and for GT in chromosome 2. Utilization of a homozygous DH population with relatively large sample size might have increased the accuracy of mapping these QTLs. The results thus obtained are valuable in breeding rice varieties with better grain quality.
Environmental Effects on Oleic Acid in Soybean Seed Oil of Plant Introductions with Elevated Oleic Concentration
Authors: Lee Jeong‐Dong , Woolard Melissa , Sleper David A. , Smith James R. , Pantalone Vincent R. , Nyinyi Catherine N. , Cardinal Andrea , Shannon J. Grover
Published: August 2009

Soybean [Glycine max (L.) Merr.] oil with oleic acid (18:1) content >500 g kg−1 is desirable for a broader role in food and industrial uses. Seed oil in commercially grown soybean genotypes averages about 230 g kg−1 oleic acid. Some maturity group (MG) II to V plant introductions (PIs) have elevated oleic concentrations of 300 to 500 g kg−1 Temperature of the growing environment during the reproductive growth stage affects oleic concentration in soybean oil. The objective of this study was to evaluate stability of oleic acid content among 15 PIs with elevated 18:1 and three checks grown in 16 environments. Oleic acid concentration of the high 18:1 checks N98‐4445A and M23 ranged from 383 to 694 g kg−1 and 428 to 572 g kg−1 with averages of 575 g kg−1 and 508 g kg−1, respectively. The PIs with the highest 18:1 were MG II to III, with most lines averaging >400 g kg−1 oleic acid concentration over 16 environments. Generally, PIs in MG II to III were less stable across environments than those in MG V. However, MG III PI 379559D ranged from 381 to 513 g kg−1 with an average 439 g kg−1 oleic acid concentration and was the most stable in oleic acid content of the 15 PIs studied. PI379559D was more stable than N98‐4445A or M23. PI417360 and PI506852 averaged highest in 18:1 (>330 g kg−1) among MG V PIs studied. Combining genes from these PIs and other sources with elevated 18:1 may be useful in developing higher oleic acid soybean genotypes.
Molecular Mapping of Stem‐Rust‐Resistance Gene Sr40 in Wheat
Authors: Wu Shuangye , Pumphrey Michael , Bai Guihua
Published: August 2009

Stem rust, caused by Puccinia graminis f. sp. tritici, was historically one of the most destructive diseases of wheat (Triticum aestivum L.) worldwide. Deployment of resistant cultivars successfully prevented rust epidemics over the past several decades. Unfortunately, race TTKS (termed Ug99) has emerged in Africa to render several stem‐rust‐resistance genes ineffective. Sr40, a stem‐rust‐resistance gene from Triticum timopheevii ssp. armeniacum, was transferred to wheat on translocation chromosome T2BL/2G#2S and provides effective levels of seedling and adult plant resistance against Ug99. Two mapping populations were developed using Ug99‐resistant line RL6088 and moderately susceptible to susceptible hard winter wheat cultivars Lakin and 2174. The parents were screened with 83 simple sequence repeats (SSR) from chromosome 2B and the polymorphic markers were analyzed on F2 populations. F2 and F2:3 populations were inoculated with North American stem rust race RKQQ at the seedling stage. Marker locus Xwmc344 was most closely linked to Sr40 (0.7 cM) in the RL6088/Lakin linkage map, followed by Xwmc474 and Xgwm374 Marker locus Xwmc474 was mapped ∼2.5 cM proximal to Sr40 in the RL6088/2174 population. Xwmc474 and Xwmc661 flanked Sr40 in both populations. Markers linked to Sr40 will be useful for marker‐assisted integration and pyramiding of Sr40 into elite wheat breeding lines, and reduction in the size of the T. timopheevii segment harboring this gene.
Generation Mean Analysis of Near‐Long‐Staple Fiber Length in TAM 94L‐25 Upland Cotton
Authors: Smith C. W. , Braden C. A. , Hequet E. F.
Published: August 2009

The U.S. traditionally markets upland cotton with a high volume instrument (HVI) upper‐half mean length (UHML) of 27 mm (34 staple) although international trade requires a minimum of 27.8 mm (35 staple). Genotypes have been developed that exhibit UHML of approximately 30 mm (∼38 staple) that are referred to as near‐long‐staple uplands (NLSU). The objective of this research was to determine gene action and heritability for near‐long‐staple length in a unique set of upland cotton genotypes. TAM 94L‐25, an NLSU, was crossed with three programmatically diverse NLSU phenotypes and a short‐staple upland (SSU) to produce the F1, F2, BCP1, and BCP2 generations for generation mean analysis (GMA). Generations were grown in a randomized complete block design at College Station, TX in 2001 and 2002. Seedcotton was ginned on a laboratory gin and advanced fiber instrument system (AFIS) fiber properties were determined. Additional improvement in fiber length is possible by crossing TAM 94L‐25 with the other NLSU phenotypes included in this study. Environment affected genetic expression with narrow sense heritability (h2) for fiber length generally lower in the TAM 94L‐25/NLSU families. Transgressive segregates were found in all families.
Molecular Genetic Linkage Map for Allotetraploid Colonial Bentgrass
Authors: Rotter David , Amundsen Keenan , Bonos Stacy A. , Meyer William A. , Warnke Scott E. , Belanger Faith C.
Published: August 2009

Interspecific hybridization is a widely used approach to improve crop species. We are pursuing the possibility of using interspecific hybridization between the turfgrass species colonial bentgrass (Agrostis capillaris L.) and creeping bentgrass (A. stolonifera L.) for the improvement of resistance to the fungal disease dollar spot (Sclerotinia homoeocarpa F.T. Bennett) in creeping bentgrass. From a field evaluation of a backcross population, it appears that introgression of dollar spot resistance from colonial bentgrass to creeping bentgrass is possible. We used the backcross population to generate the first genetic linkage map for colonial bentgrass. The map length was 1156 cM and consisted of 212 amplified fragment length polymorphic markers and 110 gene‐based markers. Colonial bentgrass is an allotetraploid species (2n = 4x = 28, A1 and A2 subgenomes). The map consisted of the expected 14 linkage groups, which could be assigned to either the A1 or A2 homoeologous subgenomes. Although there were dollar spot resistant individuals in the mapping population, no quantitative trait loci associated with resistance were detected.
Effects of Soil Drought with Nocturnal Warming on Leaf Stomatal Traits and Mesophyll Cell Ultrastructure of a Perennial Grass
Authors: Xu Z. Z. , Zhou G. S. , Shimizu H.
Published: August 2009

While water deficit and rising temperatures are progressive global problems, their combined effect on plants has received less attention. Stomatal traits, mesophyll cell ultrastructure, net photosynthetic rate, lipid peroxidation, and ion leakage were examined in leaves ofLeymus chinensis(Trin.) Tzvel. plants using native Castanozem soil. Stomatal traits and mesophyll cell ultrastructure were studied using light microscopy and transmission electron microscope. Under severe water stress, malondialdehyde and ion leakage increased, especially at high night temperatures of 30/25°C (day/night). Mild water stress increased stomatal density, especially with normal night temperatures of 30/20°C (day/night). Moderate and severe water stress did not affect stomatal density. Under water stress, mesophyll cell ultrastructures were disturbed, and the membrane systems of chloroplasts and mitochondria were broken, particularly at high night temperatures. Leaf net photosynthetic rate and stomatal conductance were negatively correlated with ion leakage and malondialdehyde. The results suggested that high night temperature may aggravate the adverse effects of soil water deficit on leaf stomatal traits and mesophyll cell ultrastructure and also enhance lipid peroxidation.