bluuebunny/crossref_metadata_2025 huggingface dataset:
Redesign of the castorbean plant body plan for optimal combine harvesting
Authors: BALDANZI M , FAMBRINI M , PUGLIESI C
Published: July 2006

The seed oil of castorbean (Ricinus communis, Euphorbiaceae) is highly appreciated in several sectors of the chemical industry. A tropical perennial, with sympodial branching, this plant presents, at the same time, both vegetative shoots and inflorescences, as well as racemes with ripe seeds. This architecture is an obstacle to harvesting the plants using the standard combine harvester which requires, as with any other seed crop, that the plants be dry. One agronomic solution is to spray the plants with desiccants. However, in this paper a genetic solution is suggested, that is, an annual plant. This model is discussed within the present knowledge of plant monocarpic senescence. A mutation that changes the quantity and/or the quality of cambial activity could reduce the secondary growth in castorbean, thus favouring the plants death. Moreover, to stop iterative growth which is at the base of the perennial form of castorbean, a non‐branching model is also proposed. The occurrence of this phenotype in some crops (maize and sunflower) and mutants (tomato, barley, etc.) is examined. Considering apical dominance as the primary mechanism at the base of a non‐branching form, a mutation capable of inducing permanent dormancy of axillary buds is discussed. Both mutation breeding and genetic engineering are suggested as major tools to obtain an annual plant of castorbean.
Nucleotide sequence variation in a small region of the Grapevine fleck virus replicase provides evidence for two sequence variants of the virus
Authors: SHI B J , HABILI N , SYMONS R H
Published: July 2006

A region encoding the putative RNA replicase domain of Grapevine fleck virus (GFkV) was amplified from infected grapevine samples using the reverse transcription‐polymerase chain reaction (RT‐PCR). Two different sizes of virus specific PCR products were consistently detected in different grapevine varieties using the same pair of primers. We selected four reference vines and carried out nucleotide sequence analysis. The size of the small product was 353 nucleotides (nt) and that of the large product was 416 nt. Database search showed that both products shared a high sequence homology with GFkV. Sequence variants producing the small size products were named GFkV353, while those giving the large size products were named GFkV416. The small size product shared a higher sequence homology with that of the published GFkV sequence from Italy, which had the same product size of 353 nt, while the large product had a 63 base insertion in that region. This insertion occurred within domain VI of the replicase gene. A survey was carried out for the presence of these two sequence variants in Australia, New Zealand, the USA, South Africa and a number of other countries. In Australia, of 3874 grapevine samples tested by the RT‐PCR assay, 492 (12.7%) contained GFkV353 and 145 (3.7%) contained GFkV416, while only six (0.1%) contained both variants. The sequence homology between these two amplified products and the corresponding regions in related viruses of tymoviruses and marafiviruses is discussed.
Screening Capsicum germplasm for resistance to tomato spotted wilt virus (TSWV)
Authors: CEBOLLA‐CORNEJO J , SOLER S , GOMAR B , SORIA M D , NUEZ F
Published: July 2006

Resistance conferred by the Tsw locus from Capsicum chinense against Tomato spotted wilt virus (TSWV) has been widely used in breeding programmes. Nevertheless, this resistance depends on inoculation conditions, and isolates able to overcome it have already been detected. In this work 29 accessions of several Capsicum species have been mechanically inoculated with TSWV to identify new sources of resistance. Five accessions showed variable percentages of resistant plants, two of which did not show local lesions on inoculated leaves, suggesting that the response was not mediated through hypersensitivity. Two of these accessions also had a remarkable reduced viral accumulation compared to susceptible control. ECU‐973., a C. chinense accession, showed the best performance against TSWV, with 100% resistant plants. This response was confirmed after mechanical inoculation with three different TSWV isolates. The resistance was maintained when the accession was inoculated with TSWV using a high pressure of viruliferous thrips. These results open new possibilities in the development of a durable resistance to TSWV in pepper.
Development and feeding efficiency of Malacosoma neustrium larvae reared with Quercus spp. leaves
Authors: VERDINELLI M , SANNA‐PASSINO G
Published: July 2006

Observations on larval development of Malacosoma neustrium were conducted both in a cork oak stand and in the laboratory by using leaves of different host trees (cork oak, holm oak and downy oak) as food source. Instars were determined using head capsule and frass measurements. In the field the larvae progressed up to the fifth instar before pupating, and the increase in head capsule width followed Dyars Rule with a rate of increase (R.I.) value of 1.74. The same number of instars was determined for the larvae reared with cork oak (R.I. = 1.73) and holm oak (R.I. = 1.70) leaves. The caterpillars reared with downy oak foliage completed larval development in five, six and seven instars and the R.I. values obtained were 1.60, 1.52 and 1.44 respectively. A lower mortality was recorded for the larvae reared on holm oak. Growth and feeding indices were determined for the larvae from the third up to the last instar. The highest leaf consumption was detected for the fifth instar larvae reared on holm oak. For the caterpillars which completed five instars before pupating, the relative consumption rate (RCR) decreased from the third up to the fifth instar: from 4.8 to 1.7 (cork oak), from 7.4 to 3.3 (holm oak) and from 14.3 to 2.1 (downy oak). The relative growth rate (RGR) was highest during the fourth stadium (0.24, 0.27 and 0.33 for larvae reared with cork oak, holm oak and downy oak leaves respectively) and decreased in the fifth instar (0.09, 0.14 and 0.14 for larvae reared with cork oak, holm oak and downy oak leaves respectively), probably because of greater expense of energy due to the approach of maturity. Feeding and growth indices could be useful to define a defoliation prediction model.
Temporal dynamics of tuber formation and related processes in a crossing population of potato (Solanum tuberosum)
Authors: CELIS‐GAMBOA CAROLINA , STRUIK P C , JACOBSEN E , VISSER R G F
Published: July 2006

The chronological relationships between stolon formation, stolon tip swelling, tuber initiation, flowering, senescence, growth and resorption of tubers were studied under field conditions in a diploid population of potato with 238 genotypes, the parental clones and seven tetraploid cultivars. Timing of tuber initiation was not closely related to the timing of stolon formation, flowering and duration of the plant cycle. Tuber initiation very often preceded stolon branching. The number and size distribution of tubers were largely influenced by the degree of stolon branching, the length of the stolon swelling period and tuber resorption. The peak production of stolons and swollen stolon tips largely took place within the flowering period, although in most genotypes, some stolon tip swelling took place until the end of the plant cycle. More information on the general temporal relationships between events related to tuber formation and plant development will contribute to a better understanding of the physiological and genetic basis of the processes leading to the production of harvestable tubers.
Seasonal variations in production and development of leather leaf fern leaves1
Authors: STRANDBERG J O
Published: July 2006

Production and development of leatherleaf fern leaves were studied using containerised plants growing in a shade house. Leaf development was partitioned into seven arbitrary development stages; the time needed for leaves to progress through each developmental stage was used to measure days required to reach maturity. Measurements were made twice each week throughout 1997. Means and variances with in emergence rates of new leaves and time needed for new leaves to pass through six leaf development stages were calculated for 26 14‐day periods throughout the year and compared with degree days, solar radiation, soil temperature, and daylight hours accumulated during the periods. Leaf production rates ranged from 0.15–0.73 leaves day−1 plant−1. The average time from emergence to maturity was 22.6 days. Both leaf production and development rates varied greatly with the seasons, and were strongly associated with the weather variables measured, but significant cyclic rate fluctuations unrelated to weather were also detected. Leaf emergence rates were more strongly related to average soil temperature, whereas leaf development rates to maturity were more strongly related to solar radiation and degree days.
Potato proteins, and other plant proteins, as potential transgenic resistance factors to pollen beetles in oilseed rape
Authors: ÅHMAN INGER , MELANDER MARGARETA
Published: July 2006

Proteinase inhibitors (PIs), lectin and patatin purified from potato tubers were tested in no‐choice feeding assays with pollen beetle larvae (Meligethes spp.). The idea was to search for resistance factors possible to introduce into oilseed rape (Brassica napus) by genetic engineering. The larval diet was prepared by soaking oilseed rape anthers in protein solutions of known concentrations. Potato lectin was the most potent in that it was the only of these proteins that reduced both larval survival and growth rate, while cysteine, aspartic and metallo PIs and patatin only reduced larval growth rate. Serine PIs had no significant effect on larval performance. Subsequently, the effect of potato lectin was compared to that of lectins from other food or feed crops, resulting in the following mortality‐ based ranking of activity: Con A from jackbean > wheat germ lectin > potato lectin > peanut lectin. In choice tests, larvae did not discriminate between Con A‐ and control‐diets. These results suggest that the effect of Con A on larvae is toxic, not deterrent. Adult response was stronger to Con A than to potato lectin in no‐choice tests, just as it was in larvae. However, adult survival rate and weight was not affected by Con A but the lectin significantly reduced adult feeding as well as oviposition rates. A resistance factor that suppresses adult feeding on flower buds is important for reduced impact of the pollen beetle on the Brassica oilseed crop.
Preparation of total RNA from a very small wheat embryo suitable for differential display
Authors: CHEN YIHUA , WEINING SONG , DAGGARD GRANT
Published: July 2006

A simple method was developed for extracting total RNA from a single mature wheat seed embryo, which is very small and hard. Guanidine thiocyanate and chloroform were employed and the grinding of the samples was performed in a microcentrifuge tube with a plastic pestle. A jacket. of liquid nitrogen and simplified procedures were applied to ensure the thorough grinding of the embryo tissue and to minimise the loss of samples. These measures substantially increased the recovery of total RNA in the extraction process. Reliable differential display was successfully achieved with the total RNA after DNase treatment and reverse transcription. This method makes it viable to study gene expression and gene regulation in a single wheat seed embryo. It may also give researchers the ability to analyse mRNAs in tissues or organs which were previously too small for RNA isolation using conventional procedures.
A wheat canopy model for use in disease management decision support systems
Authors: MILNE ALICE , PAVELEY NEIL , AUDSLEY ERIC , LIVERMORE PHILIP
Published: July 2006

A model is described which predicts those aspects of wheat canopy development and growth which are influential in determining the development of epidemics of foliar pathogens, the efficacy of foliar applied fungicides and the impact of disease on yield; specifically the emergence, expansion and senescence of upper culm leaves in relation to anthesis date. This focus on upper leaves allowed prediction of leaf emergence dates by reference to anthesis, rather than sowing. This avoided the step changes in flag leaf emergence date with temperature, reported with earlier models, without the additional complexity of a stochastic approach. The model is designed to be coupled to models of foliar disease, where the primary effect on yield is via reduction in green canopy area and hence interception of photosynthetically active radiation. Mechanisms were incorporated to allow observations of crop development during the growing season to update state variables and adjust parameters affecting future predictions. The model was calibrated using experimental data, and validated against independent observations of crop development on four wheat cultivars across seven contrasting sites in the UK. Anthesis date and upper culm leaf emergence were always predicted within one week of their observed dates.
Effects of sowing date and volunteers on the infectivity of soil infested with Gaeumannomyces graminis var. tritici and on take‐all disease in successive crops of winter wheat
Authors: GUTTERIDGE R J , HORNBY D
Published: July 2006

In a field experiment on winter wheat, take‐all on plants and the infectivity of the soil were studied in crop sequences with different combinations of sowing dates. Take‐all was negligible in the first wheat crop, but thereafter the mean disease intensity (measured using a take‐all rating, TAR, with a maximum of 300) was 108, 190, 118 and 251 in the second to fifth successive crops. In each growing season, the disease differed amongst sequences and built up more rapidly and was more intense on plants sown in mid‐September than on plants sown in mid‐October. In late‐sown plots, where volunteers had been present during the mid‐September to mid‐October period, take‐all reached an intensity intermediate between that in early‐sown plots and that in late‐sown plots that had been kept free of volunteers. Volunteers, therefore, partially offset the expected beneficial effect of decreased disease with later sowing. Differences in take‐all amongst sequences were most pronounced in the second wheat crop and early sowing of the previous wheat increased intensity of disease. In the following (third) crop, differences in disease intensity amongst sequences were smaller. Soil infectivity (measured by seedling bioassay after harvest) built up progressively from a low level after the first crop to peak after the third crop. In this build‐up phase, soil infectivity estimates were always numerically greater after harvest of early‐sown treatments than after later‐sown treatments, although never significant at P= 0.05. The greatest difference (P= 0.06) was recorded in October before sowing of the third crop, where the comparison was between soil after two previous early sowings and soil after two previous later sowings and control of volunteers. In the same autumn, presence of green cover (i.e. volunteers) was associated with a smaller loss of soil infectivity between harvest and later sowing than occurred in an absence of green cover. In 2nd–4th crops, where comparisons were available and mean TARs indicated moderate levels of take‐all, sowing later had no yield benefit, despite more take‐all and greater soil infectivity associated with early sowing. Important considerations for the management of crops at risk of take‐all are 1) choosing appropriate sowing dates to minimize take‐all or to encourage take‐all decline and 2) controlling volunteers and weed hosts where crops are sown late to minimise take‐all.
Phenological growth stages of North American ginseng (Panax quinquefolius)
Authors: PROCTOR J T A , DORAIS M , BLEIHOLDER H , WILLIS A , HACK H , MEIER V
Published: July 2006

The BBCH (Biologische Bundesanstalt, Bundessortenamt, Chemische Industrie) scale is used to describe the phonological growth stages of North American ginseng (Panax quinquefolius). Eight principal growth stages for germination and bud development, leaf development (crop canopy), root and perennating bud formation, peduncle elongation and inflorescence development, flowering and fruit set, development of fruit, ripening of fruit and senescence, and 42 secondary growth stages are described. A practical use of the scale is proposed with reference to the timing of application of agrochemicals for disease control.
Efficacy of alternatives to antibiotic chemicals for the control of fire blight of pears
Authors: TSIANTOS J , PSALLIDAS P , CHATZAKI A
Published: July 2006

The efficacy of various chemicals as alternatives to antibiotics for the control of fireblight (Erwinia amylovora) on pear trees was tested. The chemicals were applied in two ways. In 1999 and 2000, preselected pear twigs (80–90% bloom stage) were sprayed once either preventively 1 day before inoculation or curatively one or three days after artificial inoculation with pathogen concentrations of 105 and 107cfu ml−1. In 2000 and 2001, whole trees were sprayed 2 and 4 days before artificial inoculation of the flowers. From the incidence of diseased flowers it appeared that Bion (50% benzothiadiazole) at 0.2 g litre−1 H2O and Aliette (80% fosetyl‐Al) at 2.5 g litre−1 H2O showed considerable preventive action by eliciting systemic acquired resistance mostly when they were applied in the whole trees. However the best control was achieved with the antibiotic Agrept (20% streptomycin) at 0.5 g litre−1 H2O. This showed both preventive and curative action. Kocide (77% copper hydroxide) at 0.9 g litre−1 H2O, Dentamet (citric acid in chelate) at 1.5 ml litre−1 H2O, Bactosan (an extract from the plant Pongamia pinnatd) at 3.0 g litre−1 H2O and Bion at 0.1 g litre−1 H2O, showed preventive action, but only when the inoculum concentration was low.
Transgenic tobacco plants expressing Tarin 1 inhibit the growth of Pseudomonas syringae pv. tomato and the development of Spodoptera frugiperda
Authors: LEAL‐BERTIOLI SORAYA C M , PASCOAL ALETÉIA V , GUIMARÃES PATRÍCIA M , DE SÁ MARIA F GROSSI , GUIMARÃES REJANE L , MONTE DAMARES C , BERTIOLI DAVID J
Published: July 2006

The protein Tarin 1, from Colocasia esculenta, was expressed in Nicotiana tabacum. Bioassays were done on plants expressing Tarin 1 at different levels using Spodoptera frugiperda larvae, various bacteria and fungi and the root‐knot nematode Meloidogyne javanica. It was found that S. frugiperda larvae fed on transformed plants had retarded and lower pupation, lower accumulated biomass and higher mortality rate than larvae fed on control plants. Also, Tarin 1 was found to inhibit the growth in vitro of Pseudomonas syringae pv. tomato. For Meloidogyne javanica, both relative replication and root damage were greater in control plants than in transformed plants, but the results were not statistically significant. This work illustrates the effects of plants expressing Tarin 1, on the growth and development of insects and bacteria, and shows its potential for pest management.
Survival of A‐group and B‐group Leptosphaeria maculans (phoma stem canker) ascospores in air and mycelium on oilseed rape stem debris
Authors: HUANG Y J , FITT B D L , HALL A M
Published: July 2006

Mycelium of Leptosphaeria maculans survived on oilseed rape stem base debris buried in sand for 2,4, 6, 8,10 or 12 months and produced pseudothecia after subsequent exposure on the surface of the ground under natural conditions for 2–4 months, but did not survive on upper stem debris buried for 2 months. Only A‐group L. maculans ascospores were produced on the stem base debris which had been buried; no B‐group ascospores were produced. Mycelium of L. maculans survived on both stem base and upper stem debris exposed on the sand surface for 2, 4, 6, 8, 10 or 12 months and pseudothecia with viable ascospores were observed at the time of sampling. Both A‐group L. maculans (predominant on stem bases) and B‐group L. maculans (predominant on upper stems) ascospores were produced on unburied stem base and upper stem debris. Thus B‐group L. maculans survived longer on unburied debris than on buried debris. A‐group ascospores which were exposed in dry air in darkness at 5–20°C survived longer than B‐group ascospores; 10–37% of A‐group ascospores, compared with 2–31% of B‐group ascospores, survived after 35 days.
Addendum to counting by weighing and the seed testing problem
Authors: NICKERSON D M
Published: July 2006

The subject of counting by weighing as addressed in Ridout & Suntheralingam (1997) is revisited. When the coefficient of variation of the seed weights is known, we show how to modify the seed testing procedure in the aforementioned paper to account for the uncertainty introduced by obtaining a given number of seeds by weight, rather than exact counting. We find that counting by weighing requires a greater number of seeds per sub‐sample than that required by the exact counting method of Ridout & Roberts (1997). Furthermore, the number of seeds per sub‐sample increases with decreasing initial sample size used to estimate mean seed weight.
Fiji disease resistance in sugarcane: Relationship to cultivar preference in field populations of the planthopper vector Perkinsiella saccharicida
Authors: DHILEEPAN K , GREET A , RIDLEY A , CROFT B J , SMITH G R
Published: July 2006

Populations of the planthopper vector Perkinsiella saccharicida on sugarcane cultivars resistant (cvs QUO and Q87), moderately resistant (cvs Q90 and Q124) and susceptible (cvs NCo310 and Q102) to Fiji disease with known field resistance scores were monitored on the plant (2000–2001) and ratoon (2001–2002) crops. In both crops, the vector population remained very low, reaching its peak in the autumn. The vector population was significantly higher on cultivars susceptible to Fiji disease than on cultivars moderately resistant and resistant to Fiji disease. The number of P. saccharicida adults, nymphs and oviposition sites per plant increased with the increase in the Fiji disease susceptibility. The results suggest that under low vector density, cultivar preference by the planthopper vector mediates Fiji disease resistance in sugarcane. To obtain resistance ratings in the glasshouse that reflect field resistance, glasshouse‐screening trials should be conducted under both low and high vector densities, and the cultivar preference of the planthopper vector recorded along with Fiji disease incidence.
CO2 uptake by the cultivated hemiepiphytic cactus, Hylocereus undatus
Authors: NOBEL PARK S , DE LA BARRERA ERICK
Published: July 2006

The climate of the native tropical forest habitats of Hylocereus undatus, a hemiepiphytic cactus cultivated in 20 countries for its fruit, can help explain the response of its net CO2 uptake to environmental factors. Under wet conditions, about 85% of the total daily net CO2 uptake occurs at night via Crassulacean acid metabolism, leading to a high water‐use efficiency. Total daily net CO2 uptake is reduced 57% by only 10 days of drought, possibly involving stomatal closure induced by abscisic acid produced in the roots, which typically occupy a small substrate volume. Total daily net CO2 uptake for H. undatus is maximal at day/night air temperatures of 30/20°C, optimal temperatures that are higher than those for desert cacti but representative of ambient temperatures in the tropics; its total daily net CO2 uptake becomes zero at day/night air temperatures of 42/32°C. Stem damage occurs at 45°C for H. undatus, whose photosynthetic cells show little acclimation to high temperatures compared with other cacti and are also sensitive to low temperatures, ‐1.5°C killing half of these cells. Consistent with its shaded habitat, total daily net CO2 uptake is appreciable at a total daily PPF of only 2 mol m2 day' and is maximal at 20 mol m−2 day−1, above which photoinhibition reduces net CO2 uptake. Net CO2 uptake ability, which is highly correlated with stem nitrogen and chlorophyll contents, changes only gradually (halftimes of 2–3 months) as the concentration of applied N is changed. Doubling the atmospheric CO2 concentration raises the total daily net CO2 uptake of H. undatus by 34% under optimal conditions and by even larger percentages under adverse environmental conditions.
Evaluation of fungal antagonists for grey mould management in early growth of pot roses
Authors: YOHALEM D S
Published: July 2006

Several filamentous fungi can reduce disease incidence and suppress sporulation of Botrytis cinerea during early establishment and vegetative growth of pot roses. Two isolates of Ulocladium atrum were the most successful of those fungi tested, were consistently more effective than the fungicide, iprodione and not different from each other. Tween 80, added as a dispersant, had no effect on the efficacy of U. atrum. An isolate of Clonostachys rosea also gave better disease control than iprodione, although not to the levels given by isolates of U. atrum, nor was its behaviour consistent across experiments. Another isolate of C. rosea performed well in one trial, had no discernible effect in a second and was excluded from the third due to poor inoculum quality. Commercial Trichoderma harzianum preparations (Trichodex and Supresivit) failed to reduce disease incidence under the high disease pressure of these experiments, but did reduce sporulation of the pathogen relative to untreated controls.
Truncated Rep gene originated from Tomato yellow leaf curl virus‐Israel [Mild] confers strain‐specific resistance in transgenic tomato
Authors: ANTIGNUS Y , VUNSH R , LACHMAN O , PEARLSMAN M , MASLENIN L , HANANYA U , ROSNER A
Published: July 2006

Transgenic tomato plants carrying a truncated replication associated protein (T‐Rep) gene of the mild strain of Tomato yellow leaf curl virus‐Israel (TYLCV‐Is [Mild]) were prepared. The transgene encoding the first 129 amino acids of Rep conferred resistance only against the virus strain from which it was derived, while these plants were susceptible to the severe strain of TYLCV‐Is. This strain‐specific effect may be the result of high sequence divergence within the N‐terminal domains of the Rep genes of the two virus isolates which share a mere 78% sequence identity at the nucleotide level and 77% at the amino acid level. Although the transgenic tomato plants were totally resistant to whitefly inoculation with the mild strain of TYLCV‐Is, agroinoculation with the same virus strain resulted in variable resistance responses in the tested plants: while 21% of plants were totally immune to the virus, 33% were susceptible and 46% expressed a wide range of intermediate resistance characteristics. The applicability of TYLCV‐Is derived resistance in tomato is discussed.
Effects of host variety on blue willow beetle Phratora vulgatissima performance
Authors: PEACOCK LORI , HARRIS JUDY , POWERS STEPHEN
Published: July 2006

Phratora vulgatissima adults exhibit feeding preferences among willow varieties, yet little is known of the effects of willow variety on larval and adult performance. The effects of host variety on adult fitness and fecundity as well as on larval mortality and development were studied under laboratory conditions for 35 willow varieties. The host variety significantly affected the number of days that adults survived and the rates of weight change. On average, males lost weight and females gained weight. The total number of eggs, eggs day1, eggs clutch−1 and the length of the oviposition period were also significantly affected by willow variety. Progeny from eggs laid by adults fed on the different willow varieties showed significant differences in days to pupation and pupal weight when subsequently reared on Salix × dasyclados or on the same variety as fed to the adults. However, there was no correlation between these parameters on S. × dasyclados and the variety fed to adults. The willow variety fed to larvae significantly affected larval mortality (four varieties caused 100% mortality), the shape of larval growth curves (as measured by predicted final weight and time to half the final weight), the number of days to pupation and pupal weight. There were significant positive correlations between previously determined adult P. vulgatissima feeding preferences of the 35 willow varieties and the following: number of eggs laid, length of the oviposition period, larval mortality and development and change in adult weight. There was a considerable degree of variation in these correlations and some varieties did not follow the general trend indicated by the size or sign of particular correlations, for example, having a high feeding preference ranking yet few eggs laid, low larval weight and longer time to pupation. The differences found between varieties for adult and larval performance in conjunction with previously established feeding preferences offer great potential for utilising plant resistance to P. vulgatissima as a means of strategic control. Despite the general correlation of feeding preference and performance parameters, the results found here suggest that it appears to be possible for plant breeders to circumvent this trend.
Unusual filamentous virus‐like particles in symptomless blackberry associated with severe leaf curling in the virus indicator Rubus macraei, and anomalous data using a degenerate badnavirus primer in PCR of Rubus species
Authors: JONES A TEIFION , ROBERTS IM , McGAVIN WENDY J
Published: July 2006

Electron microscopy of ultrathin sections of leaves of symptomless Himalaya Giant blackberry and of the virus indicator species, Rubus macraei, showing severe leaf curl symptoms following graft inoculation with scions from this blackberry, detected highly flexuous virus‐like particles with an unusual ‘beaded’ structure. Such particles were restricted to a few vascular cells and were distinct from P‐protein common in some such cells. This virus, provisionally named Hawaiian rubus leaf curl virus (HRLCV), symptomlessly infected a wide range of Rubus species and cultivars. Badnavirus‐like bacilliform particles were observed in some cells of a single R. macraei plant showing leaf curl symptoms following graft inoculation with the causal agent of this disease symptom from Himalaya Giant blackberry after passage through red raspberry, but not in any other material. PCR with primer sets for the badnaviruses Rubus yellow net virus and Gooseberry veinbanding associated virus, showed that no Rubus sources studied contained these viruses. However, using a sequence‐specific primer set designed from the sequence of the product generated with a badnavirus degenerate primer set, a specific product was amplified from healthy plants of all of 16 raspberry cultivars and two Rubus species, but not from 16 blackberry cultivars (including cv. Himalaya Giant). All of these sources were free from viruses known to occur in Rubus. Sequence analysis of this product showed no homology with any known badnavirus, or with any other published sequences. It seems most likely therefore that a region of the raspberry genome has been amplified using the degenerate badnavirus primer set and that it is absent from the blackberry genome.
Sustainable production of crops and pastures under drought in a Mediterranean environment
Authors: TURNER NEIL C
Published: July 2006

Mediterranean environments are characterised by cool wet winters and hot dry summers. While native vegetation in Mediterranean‐climatic zones usually comprises a mixture of perennial and annual plants, agricultural development in the Mediterranean‐climatic region of Australia has led to the clearing of the perennial vegetation and its replacement with annual crops and pastures. In the Mediterranean environments of southern Australia this has led to secondary (dryland) salinisation. In order to slow land degradation, perennial trees and pasture species are being reintroduced to increase the productivity of the saline areas.

The annual crops and pastures that form the backbone of dryland farming systems in the Mediterranean‐climatic zone of Australia are grown during the cool wet winter months on incoming rainfall and mature during spring and early summer as temperatures and rates of evaporation rise and rainfall decreases. Thus, crop and pasture growth is usually curtailed by terminal drought. Where available, supplementary irrigation in spring can lead to significant increases in yield and water use efficiency. In order to sustain production of annual crops in Mediterranean environments, both agronomic and genetic options have been employed. An analysis of the yield increases of wheat in Mediterranean‐climatic regions shows that there has generally been an increase in the yields over the past decades, albeit at a lower rate than in more temperate regions. Approximately half of this increase can be attributed to agronomic improvements and half to genetic improvements. The agronomic improvements that have been utilised to sustain the increased yields include earlier planting to more closely match crop growth to rainfall distribution, use of fertilisers to increase early growth, minimum tillage to enable earlier planting and increase plant transpiration at the expense of soil evaporation, rotations to reduce weed control and disease incidence, and use of herbicides, insecticides and fungicides to reduce losses from weeds, insects and disease. Genetic improvements include changing the phenological development to better match the rainfall, increased early vigour, deeper rooting, osmotic adjustment, increased transpiration efficiency and improved assimilate storage and remobilisation.

Mediterranean environments that are subjected annually to terminal drought can be both environmentally and economically sustainable, but to maximise plant water use efficiency while maintaining crop productivity requires an understanding of the interaction between genotypes, environment and management.
Genotype and phenotype associations with drought tolerance in barley tested in North Africa
Authors: FORSTER B P , ELLIS R P , MOIR J , TALAMÈ V , SANGUINETI M C , TUBEROSA R , THIS D , TEULAT‐MERAH B , AHMED I , MARIY S A E E , BAHRI H , EL OUAHABI M , ZOUMAROU‐WALLIS N , EL‐FELLAH M , BEN SALEM M
Published: July 2006

A review is presented of genetic strategies deployed in a 3‐yr project on drought tolerance in barley. Data were collected on genetic, physiological and agronomic traits in non‐irrigated and irrigated field trials in Egypt, Morocco and Tunisia. A wide range of barley germplasm (developed from African and European cultivars, adapted landraces and wild barleys) was tested, and positive traits were found in each gene pool. The contrasting environments of the three North African countries had major effects on plant/genotype performance. Genetic effects were also detected, as were genotype × environment interactions.

A range of strategies were deployed to investigate the physiology and genetics of quantitative traits associated with field performance. Quantitative trait locus (QTL) analysis was performed using backcross lines, recombinant inbred lines and doubled haploid mapping populations. A detailed genetic map was generated in the Tadmor × (ER/Apm) recombinant inbred lines, an important mapping population specifically developed by ICARDA (Centre for Agricultural Research in Dry Areas) and CIMMYT (International Maize and Wheat Improvement Center) to study drought. Quantitative trait loci (QTLs) for grain yield and other important morphological and physiological traits were also identified in a population of doubled haploids derived from F2BCj plants from a cross between a cultivar and a wild barley accession. Significantly, the wild parental line was found to contribute a number of positive alleles for yield.

Effects of major developmental genes could explain many of the responses observed. QTLs were found to cluster around major genes controlling flowering time (sghI), plant stature (sdwI and arie.GP) and ear type (vrsl), and it is highly likely that the associations represent pleiotropic effects. Some QTLs were associated with candidate genes such as dehydrins and rubisco activase. One of the most significant results was the identification and generation of material that out performed the best local standards in the three participating North African countries; the selected lines have now entered local breeding programmes. The strategies adopted provided information on physiological traits, genotypes and genetic markers that could be used for marker‐assisted selection. Target QTLs and their associated genetic markers may be deployed in marker assisted selection programmes to match crop phenology to the field environment.
Approaches to breeding for salinity tolerance ‐ a case study on Porteresia coarctata
Authors: LATHA R , SRINIVAS RAO C , SR SUBRAMANIAM H M , EGANATHAN P , SWAMINATHAN M S
Published: July 2006

Cereals are the world's major source of food for human nutrition. Among these, rice (Oryza sativa) is the most prominent and represents the staple diet for more than two‐fifths (2.4 billion) of the world's population, making it the most important food crop of the developing world (Anon., 2000a). Rice production in vast stretches of coastal areas is hampered due to high soil salinity. This is because rice is a glycophyte and it does not grow well under saline conditions. In order to increase rice production in these areas there is a need to develop rice varieties suited to saline environments. Research has shown that Porteresia coarctata, a highly salt tolerant wild relative of rice growing in estuarine soils, is an important material for transferring salt tolerant characteristics to rice. It is quite possible that Porteresia may be used as a parent for evolving better and truly salt resistant varieties. The inadequate results and the difficulties associated with conventional breeding techniques necessitate the use of the tools of crop biotechnology in unravelling some of the characteristics of Porteresia that have been highlighted in this report. In view of the limited resources available for increasing salinity tolerance to the breeders to wild rice germplasm, Porteresia is undoubtedly one of the key source species for elevating salinity tolerance in cultivated rice.
Biological activity of tree marigold, Tithonia diversifolia, on cowpea seed bruchid, Callosobruchus maculatus (Coleoptera: Bruchidae)
Authors: ADEDIRE C O , AKINNEYE J O
Published: July 2006

The powder and ethanol extract of Tithonia diversifolia leaves were tested for their efficacy at five different concentrations (0.0%, 0.5%, 1.0%, 1.5% and 2.0%) on bruchid mortality, oviposition and adult emergence of cowpea seed beetle Callosobruchus maculatus at ambient tropical storage conditions of temperature and relative humidity. Results showed that the leaf extract had a higher bioactivity on oviposition, adult emergence and mortality of C. maculatus. The mean number of eggs laid on seeds treated with extract was reduced from 20.7 in the solvent‐treated to 4.7 at 2%Tithonia extract concentration while adult emergence reduced from a mean of 92.2 in the solvent‐treated seeds to 72.2 at 2.0% extract treatment. Mortality was 100% at higher concentrations of 3%, 4% and 5% within 24 h of extract application but at lower concentrations mortality was 73.3% and 93.3% at 1% and 2%, respectively after 24 h. Fourty‐eight hours after application, 100% mortality of adult C. maculatus was obtained at all concentrations. The mean number of eggs laid was reduced from 41.3 in the untreated to 17.3 at 2.0% powder concentration while adult emergence dropped from 98.5% in the control to 74.2% at the highest powder concentration. The powder was effective at higher concentrations and longer exposure time. At 3%, 4% and 5%, 63–75% mortalities occurred within 24 h of application while at 48 h, mortality was 76–98% at 3–5% powder application rates. The results of this study revealed T. diversifolia as a potential candidate for bioinsecticide preparations because of antiovipositional, ovicidal and knockdown properties of its products, which have some volatile components.
Seasonal infectivity of Cacopsylla pruni, vector of European stone fruit yellows phytoplasma
Authors: CARRARO L , FERRINI F , LABONNE G , ERMACORA P , LOI NAZIA
Published: July 2006

Epidemiology of European stone fruit yellows was studied by focussing on the life cycle and transmission characteristics of the vector Cacopsyllapruni. The proportion of both phytoplasma positive and inoculative insects was determined for the first C. pruni adults back colonising the stone fruit trees in spring and for the new generations of the vector, hatched at the beginning of summer. We showed that in spring, as soon as the insects moved to stone fruit trees from shelter plants, they were infective. After the vector fed on infected stone fruit trees, the proportion of phytoplasma positive insects increased. The new generation colonising Prunus species also acquired the phytoplasma from their hosts although several of these insects completed the latency period on secondary hosts. Results showed that the risk of natural transmission of European stone fruit yellows‐phytoplasma by C. pruni within orchards is high when the vector is present. These results have implications for the control of European stone fruit yellows.
Protein and oil concentration of soybean seed cultured in vitro using nutrient solutions of differing glutamine concentration
Authors: PIPOLO ANTONIO E , SINCLAIR THOMAS R , CAMARA GIL M S
Published: July 2006

Oil and protein are the most valuable components of soybean seed. Evidence indicates that growth and composition of soybean seed are controlled by supplies of carbon and nitrogen provided by the maternal plant to the seed, but it is difficult experimentally to control and quantify the precise amount of carbon and nitrogen provided to the seed by the whole plant. To examine whether oil and protein concentrations are affected by the supply of nitrogen to the seed, immature soybean seeds (Glycine max cv. Williams 82) were grown in vitro in nutrient solutions containing 20, 40, 60 or 80 mM of glutamine. The seeds were incubated in Erlenmeyer flasks for 8 days at 25°C. The rate of dry matter accumulation changed from 7.2 to 8.3 mg seed−1 day−1 as the glutamine concentration increased from 20 to 80 mM but the differences were not significant (P 0.05). Seed protein concentration increased as glutamine concentration increased from 294 mg g−1 at 20 mM glutamine to as high as 445 mg g−1 at 80 mM glutamine. Typical in vivo protein concentration of mature soybean seeds is about 400 mg g−1. Oil and protein concentrations were negatively correlated (r2= 0.44), which indicates that oil and protein synthesis are interrelated. Protein synthesis was favoured over oil synthesis when nitrogen became more abundant. The seeds used in this study clearly demonstrated a capacity to respond to nitrogen availability with changes in seed protein concentration.
The problems of sustainable water use in the Mediterranean and research requirements for agriculture
Authors: LARAUS J
Published: July 2006

This study addresses the sustainable use of water resources in the Mediterranean basin, particularly in the Southern and Eastern parts of the region, and the many problems generated by water scarcity and misuse. Water economy in the region is beset by two specific problems: high irrigation needs and changes in consumer demands (especially after population shifts from rural to urban areas and because of increasing tourism and industrialisation). The challenges presented by the water crisis are even greater because of growing populations and estimated future climatic changes in the region. The integrated management of limited water resources in the Southern and Eastern parts of the Mediterranean involves several areas of research. Those most directly related with agriculture concern improving water (and nutrient) use in agriculture through the management and breeding of irrigated and rain‐fed crops. However, these fields of research address only one face of a multi‐factorial equation that affects water sustainability in the region. Thus, other research fields include the design of comprehensive water policies and integrated planning, and technologies for advanced water treatment and re‐use. Moreover, local problems and socio‐economic aspects must be considered when addressing research issues.
Aerated subsurface irrigation water gives growth and yield benefits to zucchini, vegetable soybean and cotton in heavy clay soils
Authors: BHATTARAI S P , HUBER S , MIDMORE DAVID J
Published: July 2006

Inadequate oxygen concentration in the root zone is a constraint to plant performance particularly in heavy, compacted and/or saline soils. Sub‐surface drip irrigation (SDI) offers a means of increasing oxygen to plant roots in such soils, provided irrigation water can be hyper‐aerated or oxygenated. Hydrogen peroxide (HP) at the rate of 5 litre ha−1 at the end of each irrigation cycle was injected through SDI tape to a field‐grown zucchini (courgette) crop (Cucurbita pepo) on a saturated heavy clay soil in Queensland, Australia. Fruit yield, number and shoot weight increased by 25%, 29% and 24% respectively due to HP treatment compared to the control. Two pot experiments with vegetable soybean (Glycine max) and cotton (Gossypium hirsutum) compared the effectiveness of HP and air injection using a Mazzei air injector (a venturi), throughout the irrigation cycle in raising crop yield in a heavy clay soil kept at saturation or just under field capacity. Fresh pod yield of vegetable soybean increased by 82–96% in aeration treatments compared with the control. The yield increase was associated with more pods per plant and greater mean pod weight. Significantly higher above ground biomass and light interception were evident with aeration, irrespective of soil water treatment. Similarly cotton lint yield increased by 14–28% in aeration treatments compared with the control. The higher lint yield was associated with more squares and bolls per plant which accompanied greater above ground biomass and an increase in root mass, root length and soil respiration. Air injection and HP effected greater water use, but also brought about an enhancement of water use efficiency (WUE) for pod and lint yield, and increased leaf photosynthetic rate in both species but had no effect on transpiration rate and stomatal conductance per unit leaf area. Aeration‐induced enhanced root function was arguably responsible for greater fruit set and yield in all three crops, while in vegetable soybean greater canopy cover, radiation interception and total vegetative biomass were responsible for additional yield benefit. Increased aeration of the root zone in heavy clay soils employing either air injection or HP proved beneficial to SDI irrigated crops, irrespective of the soil water conditions, and can add value to grower investments in SDI.