bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional analysis of a NAC‐type transcription factor OsNAC6 involved in abiotic and biotic stress‐responsive gene expression in rice
Authors: Nakashima Kazuo , Tran Lam‐Son P. , Van Nguyen Dong , Fujita Miki , Maruyama Kyonoshin , Todaka Daisuke , Ito Yusuke , Hayashi Nagao , Shinozaki Kazuo , Yamaguchi‐Shinozaki Kazuko 
Published: June 2007

SummaryThe OsNAC6 gene is a member of the NAC transcription factor gene family in rice. Expression of OsNAC6 is induced by abiotic stresses, including cold, drought and high salinity. OsNAC6 gene expression is also induced by wounding and blast disease. A transactivation assay using a yeast system demonstrated that OsNAC6 functions as a transcriptional activator, and transient localization studies with OsNAC6–sGFP fusion protein revealed its nuclear localization. Transgenic rice plants over‐expressing OsNAC6 constitutively exhibited growth retardation and low reproductive yields. These transgenic rice plants showed an improved tolerance to dehydration and high‐salt stresses, and also exhibited increased tolerance to blast disease. By utilizing stress‐inducible promoters, such as the OsNAC6 promoter, it is hoped that stress‐inducible over‐expression of OsNAC6 in rice can improve stress tolerance by suppressing the negative effects of OsNAC6 on growth under normal growth conditions. The results of microarray analysis revealed that many genes that are inducible by abiotic and biotic stresses were upregulated in rice plants over‐expressing OsNAC6. A transient transactivation assay showed that OsNAC6 activates the expression of at least two genes, including a gene encoding peroxidase. Collectively, these results indicate that OsNAC6 functions as a transcriptional activator in response to abiotic and biotic stresses in plants. We conclude that OsNAC6 may serve as a useful biotechnological tool for the improvement of stress tolerance in various kinds of plants.
TaVRT2 represses transcription of the wheat vernalization gene TaVRN1
Authors: Kane Ndjido Ardo , Agharbaoui Zahra , Diallo Amadou Oury , Adam Hélène , Tominaga Yoko , Ouellet François , Sarhan Fathey 
Published: June 2007

SummaryIn wheat, VRN1/TaVRN1 and VRN2/TaVRN2 determine the growth habit and flowering time. In addition, the MADS box transcription factor VEGETATIVE TO REPRODUCTIVE TRANSITION 2 (TaVRT2) is also associated with the vernalization response in a manner similar to TaVRN2. However, the molecular relationship between these three genes and their products is unknown. Using transient expression assays in Nicotiana benthamiana, we show that TaVRT2 acts as a repressor of TaVRN1 transcription. TaVRT2 binds the CArG motif in the TaVRN1 promoter and represses its activity in vivo. In contrast, TaVRN2 does not bind the TaVRN1 promoter and has no direct effect on its activity, but it can enhance the repression effect of TaVRT2. This suggests that a repressor complex regulates the expression of TaVRN1. In winter wheat, TaVRT2, TaVRN2 and TaVRN1 transcripts accumulate in the shoot apical meristem and young leaves, and temporal expression is consistent with TaVRT2 and TaVRN2 being repressors of floral transition, whereas TaVRN1 is an activator. Non‐vernalized spring wheat grown under a short‐day photoperiod accumulates TaVRT2 and shows a delay in flowering, suggesting that TaVRT2 is regulated independently by photoperiod and low temperature. The data presented suggest that TaVRT2, in association with TaVRN2, represses the transcription of TaVRN1.
Nonsense‐mediated mRNA decay (NMD) silences the accumulation of aberrant trypsin proteinase inhibitor mRNA in Nicotiana attenuata
Authors: Wu Jianqiang , Kang Jin‐Ho , Hettenhausen Christian , Baldwin Ian T. 
Published: June 2007

SummaryIn eukaryotes, genes carrying premature termination codons (PTCs) are often associated with decreased mRNA levels compared with their counterparts without PTCs. PTC‐harboring mRNA is rapidly degraded through the nonsense‐mediated mRNA decay (NMD) pathway to prevent the accumulation of potentially detrimental truncated proteins. In a native ecotype of Nicotiana attenuata collected from Arizona (AZ), the mRNA levels of a trypsin proteinase inhibitor (TPI) gene are substantially lower than in plants collected from Utah (UT). Cloning the AZ TPI gene revealed a 6 bp deletion mutation in exon 2 resulting in a PTC and decreased mRNA levels through NMD. Silencing UPF1, 2 and 3 in N. attenuata AZ plants by virus‐induced gene silencing (VIGS) enhanced the levels of PTC‐harboring TPI mRNA, demonstrating a conserved role for UPF genes in plants. Furthermore, using cell suspension cultures that express variants of the TPI construct, we demonstrate that both intron‐containing and intronless genes are subject to NMD in plants; unlike PTCs in mammals, PTCs downstream of introns activate NMD in plants. However, when a PTC is only 4 bp upstream of an intron, the NMD surveillance mechanism is abrogated. We also demonstrate that, in an intronless TPI gene, a PTC located at the beginning or the end of the coding sequence triggers NMD less efficiently than do PTCs located at the middle of the coding sequence. Taken together, these results highlight the complexity of the NMD activation mechanisms in plants.
Silencing of the major family of NBS–LRR‐encoding genes in lettuce results in the loss of multiple resistance specificities
Authors: Wroblewski Tadeusz , Piskurewicz Urszula , Tomczak Anna , Ochoa Oswaldo , Michelmore Richard W. 
Published: June 2007

SummaryThe RGC2 gene cluster in lettuce (Lactuca sativa) is one of the largest known families of genes encoding nucleotide binding site–leucine‐rich repeat (NBS–LRR) proteins. One of its members, RGC2B, encodes Dm3 which determines resistance to downy mildew caused by the oomycete Bremia lactucae carrying the cognate avirulence gene, Avr3. We developed an efficient strategy for analysis of this large family of low expressed genes using post‐transcriptional gene silencing (PTGS). We transformed lettuce cv. Diana (carrying Dm3) using chimeric gene constructs designed to simultaneously silence RGC2B and the GUS reporter gene via the production of interfering hairpin RNA (ihpRNA). Transient assays of GUS expression in leaves accurately predicted silencing of both genes and were subsequently used to assay silencing in transgenic T1 plants and their offspring. Levels of mRNA were reduced not only for RGC2B but also for all seven diverse RGC2 family members tested. We then used the same strategy to show that the resistance specificity encoded by the genetically defined Dm18 locus in lettuce cv. Mariska is the result of two resistance specificities, only one of which was silenced by ihpRNA derived from RGC2B. Analysis of progeny from crosses between transgenic, silenced tester stocks and lettuce accessions carrying other resistance genes previously mapped to the RGC2 locus indicated that two additional resistance specificities to B. lactucae, Dm14 and Dm16, as well as resistance to lettuce root aphid (Pemphigus bursarius L.), Ra, are encoded by RGC2 family members.
Optimized Architecture for Nutrition in the Avascular Retina of Megachiroptera
Authors: Brudenall D. K. , Schwab I. R. , Lloyd W. , Giorgi P. P. , Graydon M. L. 
Published: June 2007

SummaryInvestigations were undertaken to evaluate the unique choroidal vascular system of the Megachiroptera (fruit bats) and its possible significance for retinal nutrition. Fluorescein angiography was performed and documented on Pteropus poliocephalus. Vascular casts were made of the eye of Pteropus scapulatus. Histologic evaluation was performed on P. scapulatus. Results confirmed that each papilla has a vascular core, and a unique vascular system emanating from the optic disc. The histological appearance of the choroid and retina of P. scapulatus confirmed a vascular core to the papillae with a thin, but definite Bruch's membrane. Megachiroptera have a unique vascular system to supply nutrition to the retina consisting of capillary loops within a dense, uniform mosaic of choroidal projections or papillae, which permit the diffusion of metabolites to the retina and a heretofore undescribed vascular tuft emanating from the optic disc. We suggest that this vascular system provides nutrition by diffusion to a thick avascular retina, without any shadowing by vessels, and allows for nocturnal visual acuity and light‐gathering capabilities.
Developmental Changes of Seminiferous Tubule in Prenatal, Postnatal and Adult Testis of Bonnet Monkey (Macaca radiata)
Authors: Prakash S. , Prithiviraj E. , Suresh S. 
Published: June 2007

SummaryThis paper is a part of our study on the male reproductive system of bonnet monkey. The developmental changes in testis of bonnet monkey were studied qualitatively and quantitatively, at the light microscopy level. Testicular development appears to primarily involve tubular growth that starts immediately after birth. There is a gradual increase in the number of tubules in the prenatal to neonatal stage in testis, without an increase in the volume. Increase in the number of tubules in the neonatal testis was achieved by an increase in the length of the tubules and reduction in the interstitial proportion. Scattered spermatogonial cells in the tubules of neonatal testis indicate the rapid growth rate of the tubules. Increase in tubular length along with diameter seems to be a continuous process until puberty. This is the first report on the developmental changes in the testis during fetal, postnatal and adult stages in the bonnet monkey.
Effect of epicuticular waxes of poplar hybrids on the aphid Chaitophorus leucomelas (Hemiptera: Aphididae)
Authors: Alfaro‐Tapia A. , Verdugo J. A. , Astudillo L. A. , Ramírez C. C. 
Published: June 2007

Abstract:  Insect response to plant surface features is a critical step in host‐finding and acceptance of herbivorous insects. The plant surface is usually covered with epicuticular waxes (EWs), which are not only involved in water physiology, but also provide resistance to insects. In the present work the probing behaviour and performance of the aphid Chaitophorus leucomelas Koch (Hemiptera: Aphididae) on dewaxed and waxed leaves of two poplar hybrids, [(Populus trichocarpa Torr. & Gray × Populus deltoides Bartram ex Marshall) × P. deltoides] (TD × D) and [(P. trichocarpa × Populus maximowiczii Henry) × (P. trichocarpa × P. maximowiczii)] (TM × TM), previously reported as susceptible and resistant, respectively, are described. Laboratory experiments showed that in naturally waxed leaves of the resistant hybrids, aphids devoted less time to probing and more time to non‐probing behaviour when compared with their behaviour on susceptible hybrids. These differences were not present when leaves of these hybrids were experimentally dewaxed. A field experiment demonstrated that aphid reproductive performance was affected by hybrid genotype (higher in the TD × D) but not by EWs, although a trend of lower performance on dewaxed leaves in both hybrids was apparent. SEM analysis of EWs revealed micromorphological differences between both hybrids. These results support the idea that EWs affect aphid behaviour in poplars, with a rather slight impact on reproductive performance.
Suppression of the stored‐product insect Tribolium confusum by Xylocoris flavipes and Amphibolus venator
Authors: Murata M. , Imamura T. , Miyanoshita A. 
Published: June 2007

Abstract:  We evaluated the suppression of the confused flour beetle, Tribolium confusum, by the anthocorid bug Xylocoris flavipes and the reduviid bug Amphibolus venator. Four treatments were tested: X. flavipes adults, A. venator adults, X. flavipes adults and A. venator adults released, and control (no predators). After 25 days, X. flavipes alone showed 96.9% suppression of T. confusum, A. venator alone showed 76.2% suppression and both the predatory bugs together showed 95.6% suppression. The rates of loss of whole‐wheat flour as an index of damage caused by T. confusum were 2.7%, 6.4%, 3.6% and 11.7% in X. flavipes adults, A. venator adults, X. flavipes adults and A. venator adults released, and control respectively. Furthermore, A. venator attacked X. flavipes adults but not X. flavipes nymphs. The possibility of using both X. flavipes and A. venator against T. confusum is discussed.
Reappearance of Cucumber mosaic virus Isolates Belonging to Subgroup IB in Tomato Plants in North‐eastern Spain
Authors: Aramburu J. , Galipienso L. , López C. 
Published: June 2007

AbstractA disease characterized by symptomless leaves and fruit decolouration, loss of consistency and mild deformation on ripening was detected in tomato fields in north‐eastern Spain during 2003 and 2004. DAS‐ELISA analysis revealed the presence of the Cucumber mosaic virus (CMV) in all diseased plants. CMV isolates were characterized by polyacrylamide gel electrophoresis (PAGE) analysis of double‐stranded RNAs (dsRNAs) and nucleotide sequence analysis, and compared with some CMV isolates belonging to different subgroups used as controls. A total of 12 isolates obtained from the infected tomato plants selected for this study gave the same electrophoresis pattern for the three genomic dsRNAs, which was different to the patterns showed by the CMV isolates collected in the same region a few years ago. The identity of the complete nucleotide sequence of one of these CMV isolates and the partial sequence of other five isolates compared to the Tfn strain from Italy and the BAR92/1 isolate from tomato collected in Barcelona in 1992 was higher than 99%, both belonging to subgroup IB of CMV. The CMV isolates of this subgroup found in eastern Spain in previous studies were not detected after 1996. The nucleotide sequences of two isolates that were chosen as representatives of the CMV isolates more frequently detected in previous years revealed that they belonged to the CMV subgroups IA. The origin and the possible causes of reappearance of CMV IB isolates in north‐eastern Spain are discussed.
Effects of the Harvest Method on the Infestation of Chestnuts (Castanea sativa) by Insects and Moulds
Authors: Sieber T. N. , Jermini M. , Conedera M. 
Published: June 2007

AbstractChestnuts were collected either every 7 days from suspended nets used to intercept the fruits, every 2 days from the ground or every 7 days from the ground. Nuts were visually inspected after collection for the presence of exit holes of the chestnut weevil (Curculio elephas) and the chestnut moth (Cydia splendana), and 20 nuts per sampling and tree were bisected to assess fungal colonization. Apparently healthy nuts were incubated at 24°C and 70–80% relative humidity for 21 days. All nuts were bisected after incubation and examined for the presence of insects and moulds. The harvest method did not have a statistically significant effect on either moulding or insect infestation except onAmphiporthe castanea. This vertically transmitted fungal endophyte was less frequently isolated from fruits collected after 7 days from the ground. The black rot fungusCiboria batschianadid not occur in chestnuts intercepted in nets, but the difference to chestnuts collected from the ground was statistically not significant. The frequency of nuts colonized byC. batschianawas low in general probably due to the hot and dry summer in 2003. Big, marketable fruits appeared to be less frequently colonized by insects and moulds right after collection. This difference disappeared after incubation except for the chestnut moth. The mother tree had the greatest effect on fungal and insect infestation, indicating the importance of the genetic disposition and/or the phytosanitary situation of each tree. The chestnut weevil preferred chestnuts of the variety ‘Lüina’ to those of the variety ‘Torcion’, whereas the fungiA. castanea,Trichothecium roseum,Clonostachys roseaandPenicilliumspp. preferentially colonized chestnuts of the variety ‘Torcion’.
Determination of Deoxynivalenol and Nivalenol Chemotypes of Fusarium graminearum Isolates from China by PCR Assay
Authors: Ji L. , Cao K. , Hu T. , Wang S. 
Published: June 2007

Abstract Fusarium graminearum is the main causative agent of cereal scab and maize cob rot in China. Two hundred and fifty‐five F. graminearum isolates were obtained from wheat, barley and maize from Hebei, Heilongjiang and Hubei, provinces with distinct climate conditions and cropping systems. The isolates were confirmed to be F. graminearum by polymerase chain reaction (PCR) assay using F. graminearum species‐specific primers Fg16F/Fg16R. Two populations, 7C1 and 6A5, were identified to exist in China. The 6A5 population was predominant in Hubei in central China along the Yangtze River, whereas the 7C1 population was predominant in Heilongjiang and Hebei in northern China. Based on sequences of Tri13 and Tri3, genes involved in the mycotoxin biosynthetic pathway, PCR assays were used to detect 3‐acetyldeoxynivalenol (3‐ADON), 15‐acetyldeoxynivalenol (15‐ADON) and nivalenol (NIV) chemotypes. All three chemotypes of F. graminearum were identified, with 15‐ADON chemotype predominating overall. A greater proportion of 3‐ADON chemotype was found in Hubei, whereas a greater proportion of 15‐ADON was found in Heilongjiang and Hebei.
Identification and Regulation of Genes from a Biocontrol Strain of Fusarium oxysporum
Authors: Fravel D. R. , Moravec B. C. , Bailey B. A. 
Published: June 2007

AbstractDifferential display with three time points revealed that thiram altered expression of numerous genes in the biocontrol fungus Fusarium oxysporum CS‐20. Of the 101 bands purified from the differential display gel, 86 were successfully cloned, and 64 sequenced. Based on nucleic acid sequences, homology to known products was found using BLASTn for 26 sequences and homology to hypothetical proteins was found for six sequences, also from Gibberella zeae. One band (BM1 24‐1) showed homology to an ABC transporter from three different fungi. Because of its association with detoxification functions, the ABC transporter was selected for further study. Mycelia of CS‐20 were exposed to 25 μg active ingredient (a.i.) thiram in liquid culture for various times from 0 to 8 h. Quantitative real‐time PCR was used to evaluate gene expression. At 30 min after treatment with thiram, the ABC transporter was upregulated 20‐ to 25‐fold relative to the control treatment. The ABC transporter was upregulated 15‐fold at 1 h after treatment and 10‐fold at 2 h. At 8 h after treatment, there was no difference between treated and non‐treated for expression of the ABC transporter. Transcription of the gene encoding EST BM1 24‐1 is induced in response to thiram treatment and may function in providing resistance in F. oxysporum isolate CS‐20 to fungicides and other toxins. Tolerance to toxins may be critical to the successful inclusion of CS‐20 in disease control strategies in cropping systems.
Phylogenetic Analysis of Iris yellow spot virus Isolates from Onion (Allium cepa) in Georgia (USA) and Peru
Authors: Nischwitz C. , Pappu H. R. , Mullis S. W. , Sparks A. N. , Langston D. R. , Csinos A. S. , Gitaitis R. D. 
Published: June 2007

Abstract Iris yellow spot virus (IYSV) was first observed in sweet onions in Georgia (USA) in 2003 in the Vidalia region. The virus had been reported in the onion‐growing regions in western USA several years before being detected in Georgia in the east. Although symptoms were observed on onions in Peru several years earlier, the presence of IYSV was not confirmed in Peru until after the virus was detected in Georgia. We characterized nine isolates of IYSV recovered from sweet onions in both Georgia (four isolates) and Peru (five isolates) by sequencing the nucleocapsid (N) gene and compared those sequences with sequences available in GenBank. Sequence divergence between IYSV isolates from Georgia and Peru was low with 1.1%, and comparisons with IYSV isolates from other regions showed divergence of up to 11.4%. Bootstrap analysis indicated with a high degree of confidence that the Georgia and Peruvian isolates fell into the same clade and were different from known isolates from western USA that fell into sister clades. The high degree of similarity between Georgia and Peruvian isolates suggests that gene flow occurred from Peru into Georgia.
Evaluation of Water Yam (Dioscorea alata L.) Germplasm for Reaction to Yam Anthracnose and Virus Diseases and their Effect on Yield
Authors: Egesi C. N. , Odu B. O. , Ogunyemi S. , Asiedu R. , Hughes J. 
Published: June 2007

AbstractUse of genetic resistance is the most practical and economic way to manage major diseases of yams. In a search for sources of resistance, 40 water yam (Dioscorea alata L.) accessions from Benin, Ghana, Nigeria and Puerto Rico were screened under natural disease infection conditions in Ibadan, Nigeria. The accessions were evaluated at 1, 3 and 6 months after planting (MAP) for severity of yam anthracnose and viral diseases. The effect of the pathogens on yield was also evaluated at harvest 9 MAP. There were significant differences (P < 0.001) between accessions for severities of anthracnose and viral diseases. Eight (20%) of them had lower anthracnose area under disease progress curves (AUDPC) values than the resistant check while 10 (25%) had AUDPC values below the trial mean. There were significant variations (P < 0.001) in yield components among the accessions. There was significant negative correlation of anthracnose severity with fresh tuber yield (r = −0.51) and with number of tubers per plot (r = −0.40). Similarly, significant negative correlations were observed of virus disease severity with fresh tuber yield (r = −0.78) and number of tubers per plot (r = −0.65). Linear regression models also showed that the fresh yield had significant negative relationships with anthracnose (R2 = 0.26) and viral (R2 = 0.62) diseases. The accessions identified as resistant constitute a valuable resource for breeding of resistant germplasm.
Eradication of Polymyxa betae by Thermal and Anaerobic Conditions and in the Presence of Compost Leachate
Authors: Van Rijn E. , Termorshuizen A. J. 
Published: June 2007

AbstractThe abiotic conditions required for eradication of Polymyxa betae, the vector of Beet necrotic yellow vein virus in sugar beet, were investigated. Survival of resting spores of P. betae was determined under aerobic (30 min, 4 days and 21 days) and anaerobic (4 days) conditions under several temperature regimes in a water suspension and in leachate extracted from an aerobic compost heap. In water under aerobic conditions the lethal temperature was 60, 55 and 40°C for exposure times of 30 min, 4 days and 21 days, respectively. The effect of compost leachate and/or anaerobic conditions on survival of P. betae depended on temperature. After incubation for 4 days at 20°C, no significant effects of anaerobic conditions or leachate on the survival of P. betae were found. However, at 40°C for 4 days under anaerobic conditions, survival of P. betae was significantly lower than survival under aerobic conditions in water as well as in leachate. In leachate taken from an aerobic compost heap, aerobically incubated at 40°C for 4 days, survival of P. betae was significantly lower than survival in water at the same temperature. As anaerobic spots are prevalent in aerobic compost heaps, especially during the thermophilic phase, actual inactivation temperatures under composting conditions are likely to be lower than the temperatures we found for eradication in water under aerobic conditions.