Regional Breeding Programs Research Articles

Genetic Dissection of End-Use Quality Traits in Adapted Soft White Winter Wheat.

Soft white wheat is used in domestic and foreign markets for various end products requiring specific quality profiles. Phenotyping for end-use quality traits can be costly, time-consuming and destructive in nature, so it is advantageous to use molecular markers to select experimental lines with superior traits. An association mapping panel of 469 soft white winter wheat cultivars and advanced generation breeding lines was developed from regional breeding programs in the U.S. Pacific Northwest. This panel was genotyped on a wheat-specific 90 K iSelect single nucleotide polymorphism (SNP) chip. A total of 15,229 high quality SNPs were selected and combined with best linear unbiased predictions (BLUPs) from historical phenotypic data of the genotypes in the panel. Genome-wide association mapping was conducted using the Fixed and random model Circulating Probability Unification (FarmCPU). A total of 105 significant marker-trait associations were detected across 19 chromosomes. Potentially new loci for total flour yield, lactic acid solvent retention capacity, flour sodium dodecyl sulfate sedimentation and flour swelling volume were also detected. Better understanding of the genetic factors impacting end-use quality enable breeders to more effectively discard poor quality germplasm and increase frequencies of favorable end-use quality alleles in their breeding populations.

A Novel, Economical Way to Assess Virulence in Field Populations of Hessian Fly (Diptera: Cecidomyiidae) Utilizing Wheat Resistance Gene H13 as a Model.

Mayetiola destructor (Say) is a serious pest of wheat, Triticum aestivum L., in North America, North Africa, and Central Asia. Singly deployed resistance genes in wheat cultivars have provided effective management of Hessian fly populations for >50 yr. Thirty-five H genes have been documented. Defense mediated by the H gene constitutes strong selection on the Hessian fly population, killing 100% of larvae. A mutation in a matching Hessian fly avirulence gene confers virulence to the H gene, leading to survival on the resistant plant. As the frequency of virulence rises in the population, the H gene loses its effectiveness for pest management. Knowing the frequency of virulence in the population is not only important for monitoring but also for decisions about which H gene should be deployed in regional wheat breeding programs. Here, we present a novel assay for detecting virulence in the field. Hessian fly males were collected in Alabama, Georgia, North Carolina, and South Carolina using sticky traps baited with Hessian fly sex pheromone. Utilizing two PCR reactions, diagnostic molecular markers for the six alleles controlling avirulence and virulence to H13 can be scored based on band size. Throughout the southeast, all three avirulence and three virulence alleles can be identified. In South Carolina, the PCR assay was sensitive enough to detect the spread of virulence into two counties previously documented as 100% susceptible to H13. The new assay also indicates that the previous methods overestimated virulence in the field owing to scoring of the plant instead of the insect.

Genetic Characterization and Pathogenicity of Rhizoctonia solani Associated with Common Bean Web Blight in the Main Bean Growing area of Argentina

AbstractCommon bean web blight (WB), caused by the fungus Rhizoctonia solani (teleomorph Thanatephorus cucumeris), is among the endemic fungal diseases of major impact in north‐western Argentina (NWA). This study aimed to analyse the genetic and pathogenic diversity of R. solani in Salta, NWA, where 97 isolates were recovered from commercial bean cultivars and wild beans showing WB symptoms in a major bean production area. The isolates were characterized on the basis of specific primers, rDNA‐ITS sequences and morphological characteristics. All the isolates were identified as R. solani AG 2‐2WB, and they exhibited considerable intragroup variation. The phylogenetic tree generated with the ITS sequences confirmed the isolates identification. Aggressiveness of the isolates towards bean seedlings was assessed in the greenhouse. A great variability in virulence was observed among the isolates analysed. On the basis of the disease reaction on foliar tissues, the isolates were grouped into three virulence categories as follows: weakly virulent (30%), moderately virulent (38%) and highly virulent (32%). However, no correlation between virulence and geographical origin was detected. The information generated in this study provides initial data on the population variability of the WB pathogen in north‐western Argentina and represents a valuable contribution to regional breeding programmes aimed to obtain cultivars with durable resistance.

Genotype by environment interaction of “carioca” seeded common bean advanced lines in northeastern Brazil

The objectives of the present work were to identify common bean lines with high grain yield, adaptability and stability; stratify the environment; and detect the most important factors for the genotype by environment (G×E) interaction in northeastern Brazil. Nineteen experiments were conducted in a randomized block design with three replications during the rainy growing season at 11 locations in the States of Pernambuco, Alagoas, Sergipe, and Bahia in 2009 and 2010. In each experiment, 16 “carioca” seeded lines were evaluated, and the grain yield, assessed. Data were subjected to analyses of variance and adaptability and stability by the methodologies of Annicchiarico and Additive Main Effects and Multiplicative Interactions (AMMI), analysis of the factors for environmental stratification and joint analysis with decomposition of the G×E interaction in genotype by year and genotype by location. According to the AMMI method, BRS Estilo and CNFC 11951 were selected as stable high-yielding lines. CNFC 11954, IPR Juriti, CNFC 11948 and BRS Estilo were identified as stable high-yielding lines based on the methodology of Annicchiarico. BRS Estilo was identified as stable according to both methodologies and was therefore considered suitable for growth in the Northeast region for use as a parent line in regional breeding programs. The locations in this region used to test the common bean lines were informative, except Carira, which could be eliminated from the assay network. Interaction among genotypes, locations and years were observed, suggesting that assessments shoud be conducted at the largest number of locations and years, in this order of importance.

Identification of SNP and SSR Markers in Finger Millet Using Next Generation Sequencing Technologies.

Finger millet is an important cereal crop in eastern Africa and southern India with excellent grain storage quality and unique ability to thrive in extreme environmental conditions. Since negligible attention has been paid to improving this crop to date, the current study used Next Generation Sequencing (NGS) technologies to develop both Simple Sequence Repeat (SSR) and Single Nucleotide Polymorphism (SNP) markers. Genomic DNA from cultivated finger millet genotypes KNE755 and KNE796 was sequenced using both Roche 454 and Illumina technologies. Non-organelle sequencing reads were assembled into 207 Mbp representing approximately 13% of the finger millet genome. We identified 10,327 SSRs and 23,285 non-homeologous SNPs and tested 101 of each for polymorphism across a diverse set of wild and cultivated finger millet germplasm. For the 49 polymorphic SSRs, the mean polymorphism information content (PIC) was 0.42, ranging from 0.16 to 0.77. We also validated 92 SNP markers, 80 of which were polymorphic with a mean PIC of 0.29 across 30 wild and 59 cultivated accessions. Seventy-six of the 80 SNPs were polymorphic across 30 wild germplasm with a mean PIC of 0.30 while only 22 of the SNP markers showed polymorphism among the 59 cultivated accessions with an average PIC value of 0.15. Genetic diversity analysis using the polymorphic SNP markers revealed two major clusters; one of wild and another of cultivated accessions. Detailed STRUCTURE analysis confirmed this grouping pattern and further revealed 2 sub-populations within wild E. coracana subsp. africana. Both STRUCTURE and genetic diversity analysis assisted with the correct identification of the new germplasm collections. These polymorphic SSR and SNP markers are a significant addition to the existing 82 published SSRs, especially with regard to the previously reported low polymorphism levels in finger millet. Our results also reveal an unexploited finger millet genetic resource that can be included in the regional breeding programs in order to efficiently optimize productivity.

Evaluation of agronomic traits and spectral reflectance in Pacific Northwest winter wheat under rain-fed and irrigated conditions

The US Pacific Northwest (PNW) is characterized by high latitude and Mediterranean climate where wheat production is predominantly rain-fed and often subject to low soil moisture. As a result, selection for drought-adaptive traits in modern cultivars has been an integral component of the regional breeding programs. The goal of this research was to evaluate phenotypic associations of morpho-physiological traits and their response to soil moisture variation in winter wheat germplasm adapted to the PNW. A panel of 402 winter wheat accessions (87 hard and 315 soft) was evaluated for spectral reflectance indices (SRIs), canopy temperature (CT), plant stature, phenology, grain yield, and yield components under rain-fed and irrigated conditions in 2012–2014. Variation in soil moisture and temperature cumulatively explained 86% of total yield variation across years and locations. The phenotypic associations of yield with phenology, plant height, and CT were environment dependent. Various SRIs related to biomass, stay green, pigment composition, and hydration status showed consistent patterns of response to drought and strong correlations with yield (p<0.001). The compensatory interaction of grain number and weight was indicated in the negative correlation between thousand kernel weight and grain number per spike across moisture regimes. Area under vegetation index curve (AUVIC) explained 53–88% of the total variation in stay green estimated from visual score of flag leaf senescence (p<0.001). Principal component analysis revealed three major clusters that explained more than 76% of interrelations among traits. The market classes within the study population showed differentiation with respect to these traits. This study highlights the potential use of spectral radiometry in field screening of winter wheat for grain yield and drought adaptation in Mediterranean-like environments.

Evaluating Barley for the Emerging Craft Malting Industry in Western Washington

Craft malting companies are emerging in response to demand from the rapidly growing North American craft brewing industry, and creating a market for malting barley (Hordeum vulgare L.) in production regions considered to be of minor importance for this crop. Growing malting barley in these under‐represented areas, such as western Washington, requires identification of cultivars with suitable agronomic and quality characteristics. Twelve two‐row spring barley cultivars were evaluated for 2 yr at four western Washington locations to assess suitability for craft malt production in the region. Standard North American malting cultivars had lower yield stability than locally adapted feed cultivars. Pre‐harvest sprouting reduced falling number and germination capacity resulting in a high proportion of samples unsuitable for malt quality evaluation. Cultivars with the highest levels of resistance to pre‐harvest sprouting did not meet malt quality standards when malted according to standard micro‐malting methods. However, craft maltsters have more flexibility to alter processing conditions to produce malt from cultivars previously deemed unacceptable for large‐scale malting and brewing. Craft brewer specifications for malt are also different from large‐scale industry. The current work suggests the need to adjust the malting process to work with locally adapted cultivars while expanding regional testing and breeding programs. Demand for barley for craft malt production outside of major production regions is increasing. Standard North American malting barley cultivars are susceptible to preharvest sprouting and foliar pathogens common in nontraditional growing regions such as western Washington. To meet demand for craft breweries the emerging craft malting industry will need to find ways to work with locally adapted cultivars while expanding regional testing and breeding programs.

Molecular evaluation of Ethiopian sweet sorghum germplasm and their contribution to regional breeding programs

Sweet sorghum is an excellent feedstock for ethanol production and is also used for food and livestock feed. Germplasm collection and characterization in sweet sorghum is a crucial step towards breeding and development of superior genotypes for various end-uses. In the present study, 13 Simple Sequence Repeat (SSR) markers were used for genotyping 175 Ethiopian sweet sorghum genotypes alongside 27 improved accessions from eastern and southern Africa. All the tested markers detected 159 alleles and a high degree of polymorphism information content (PIC) averaging 0.69. A comparison between Ethiopian and improved accessions revealed higher allele numbers (124) in Ethiopian than improved accessions (92 alleles). More than half (65 out of 124) of the alleles observed in the Ethiopian accessions were rare (<5%) and 64 were private (only present within Ethiopian accessions) while in the improved accessions, 41% and 38% of the alleles detected were rare and private respectively. Both weighted Neighbor Joining-based clustering and hierarchical clustering grouped the 202 accessions into three major clusters based on geographical origin. Ethiopian accessions from the north (north Wello and south Tigray) not only clustered separately from accessions from the west central and eastern Ethiopia, but were also distinct from most of the improved genotypes. Our results reveal an unexploited highly diverse sweet sorghum genetic resource from Ethiopia that can be included in the regional breeding programs in order to efficiently optimize productivity.

Ampelographic characterization of white grapevine cul-tivars (Vitis vinifera L.) grown in Palestine

Abstract: In Palestine, grape culture consists of ecotypes and cultivars (also called local varieties), for which a large number of homonymous and synonymous designations exist as well as misnaming of cultivars. The present study is the first report using detailed ampelographic characterizations (39 informative traits) to assess genetic diversity and detect similarities among sixteen accessions collected from putative diverse grape genotypes In general, 30 descriptors presented highly and satisfactory divergent genotypes, whereas the remaining traits showed no or very little ampelographic variation. Based on the similarity matrix and the resulting dendrogram of these ampelographic data, distinguishable genotypes as well as some cases of synonymies and homonymies clearly exist. A synonymy case seemed to be in four genotypes including Jandali-Mfarad, Jan-dali-Mrazraz, Jandali, and Hamadani-Mattar, which indeed showed genetic distances of less than 0.5, sug-gesting their relatedness, and the possibility that they are the same genotype, but with different names. In addition, homonym cases also occur in the following pairs of “Marawi’s, Hamadani’s, and Zaini’s genotypes, in which each pair seems to be two distinctive genotypes. Finally, among the 16 examined genotypes, the Zaini-Baladi genotype tended to show the highest genetic distance values from the others and thus could be potentially incorporated into any further local or regional breeding programs as well as germplasm conservation.

Ampelographic characterization of white grapevine cul-tivars (Vitis vinifera L.) grown in Palestine

Abstract: In Palestine, grape culture consists of ecotypes and cultivars (also called local varieties), for which a large number of homonymous and synonymous designations exist as well as misnaming of cultivars. The present study is the first report using detailed ampelographic characterizations (39 informative traits) to assess genetic diversity and detect similarities among sixteen accessions collected from putative diverse grape genotypes In general, 30 descriptors presented highly and satisfactory divergent genotypes, whereas the remaining traits showed no or very little ampelographic variation. Based on the similarity matrix and the resulting dendrogram of these ampelographic data, distinguishable genotypes as well as some cases of synonymies and homonymies clearly exist. A synonymy case seemed to be in four genotypes including Jandali-Mfarad, Jan-dali-Mrazraz, Jandali, and Hamadani-Mattar, which indeed showed genetic distances of less than 0.5, sug-gesting their relatedness, and the possibility that they are the same genotype, but with different names. In addition, homonym cases also occur in the following pairs of “Marawi’s, Hamadani’s, and Zaini’s genotypes, in which each pair seems to be two distinctive genotypes. Finally, among the 16 examined genotypes, the Zaini-Baladi genotype tended to show the highest genetic distance values from the others and thus could be potentially incorporated into any further local or regional breeding programs as well as germplasm conservation.

The use of the gonadotropin-releasing hormone analog deslorelin for short-term contraception in red pandas (Ailurus fulgens)

Red pandas (Ailurus fulgens) are threatened with extinction owing to habitat loss, exacerbated by their unique ecology and low fecundity. Regional breeding programs manage captive red panda populations. Recommendations not to breed may be made for various reasons, including genetic overrepresentation of certain individuals. No recommendations have been published on the use of contraception for red pandas. This article discusses the use of the GnRH analog deslorelin as a reversible method of contraception in both male and female pandas. The mean time from last contraception to conception was 3 years with a 4.6-mg deslorelin implant. The average dose of GnRH implant received was 1.09 mg/kg (range, 0.88–1.32). Males returned to breeding sooner than females. No reproductive side effects were noted with up to three consecutive annual GnRH implants.

Using logistic regression models for selection in non-replicated sugarcane breeding populations

Increasing selection efficiency in un-replicated populations has remained a challenge to sugarcane breeders due to the effects of genotype by environment interaction and competition among plots. Therefore studies aimed at exploring models to improve selection efficiency are required. At the South African Sugarcane Research Institute, the Stage II selection populations are planted to un-replicated plots. Visual selection, which is known to be subjective, is used to determine the genotypes advanced. Although path coefficient analysis has identified important yield components, there is little use of that knowledge to enhance selection. This study demonstrates the use of logistic regression model as a statistical decision support tool to enhance selection in un-replicated populations. The logistic regression model used stalk number, stalk height, stalk diameter and estimable recoverable crystal (ERC) % cane to predict sugar yield. The data were collected from Stage II populations across regional breeding programs and analysed using the logistic procedure of Statistical Analysis System. The Likelihood Ratio, Score and Wald statistics were highly significant (P < 0.0001) indicating the robustness of the models. Stalk number is the most influential component to sugar yield followed by diameter, height and ERC % cane. The coefficients of the yield components varied across different programs indicating the potential of the analysis to determine yield component combination. Genotypes selected using the models produced significantly higher trait values than those rejected. The logistic regression models should enhance selection efficiency in un-replicated populations as well as provide for the evaluation of breeding populations and trait combinations across regional breeding programs.

Family selection gains for quality traits among South African sugarcane breeding populations

In sugarcane breeding, family selection has been shown to produce larger gains than individual plant selection. During family selection, whole families of seedlings are selected or rejected based on data derived from replicated family plots. The objective of this study was to determine predicted family selection gains and evaluate their implications for variety improvement in terms of quality traits among sugarcane breeding populations of the South African Sugarcane Research Institute's regional breeding programmes. The data was collected from seven breeding populations and analysed using the Statistical Analysis System (SAS). All the quality traits showed highly significant family effects variance components. There were consistent increases in heritability and gains to selection with advancing population series indicating benefits from indirect recurrent selection. Brix % cane, because it costs less to measure, could be used to evaluate within family variability. The B, C, U and F populations produced larger and more consistent selection gains than K, T and S. Recurrent selection could be used to enhance breeding for quality traits.

Trait Diversity and Potential for Selection Indices Based on Variation Among Regionally Adapted Processing Tomato Germplasm

For many horticultural crops, selection is based on quality as well as yield. To investigate the distribution of trait variation and identify those attributes appropriate for developing selection indices, we collected and organized information related to fruit size, shape, color, soluble solids, acid, and yield traits for 143 processing tomato (Solanum lycopersicum L.) lines from North America. Evaluation of the germplasm panel was conducted in a multiyear, multilocation trial. Data were stored in a flat-file format and in a trait ontology database, providing a public archive. We estimated variance components and proportion of variance resulting from genetics for each trait. Genetic variance was low to moderate (range, 0.03–0.51) for most traits, indicating high environmental influence on trait expression and/or complex genetic architecture. Phenotypic values for each line were estimated across environments as best linear unbiased predictors (BLUPs). Principal components (PC) analysis using the trait BLUPs provided a means to assess which traits explained variation in the germplasm. The first two PCs explained 28.0% and 16.2% of the variance and were heavily weighted by measures of fruit shape and size. The third PC explained 12.9% of the phenotypic variance and was determined by fruit color and yield components. Trait BLUPs and the first three PCs were also used to explore the relationship between phenotypes and the origin of the accessions. We were able to differentiate germplasm for fruit size, fruit shape, yield, soluble solids, and color based on origin, indicating regional breeding programs provide a source of trait variation. These analyses suggest that multitrait selection indices could be established that encompass quality traits in addition to yield. However, such indices will need to balance trait correlations and be consistent with market valuation.

Downy mildew resistance in maize (Zea mays L.) across Peronosclerospora species in lowland tropical Asia

Downy mildew (DM) is one of the most destructive diseases of maize in the humid sub-tropical and tropical regions of Asia. The most effective and efficient way of managing losses due to DM is to develop durable host-plant resistance in Asian maize across different DM pathogens. We assessed resistance in released DM (P. zeae) resistant CIMMYT maize lines (CMLs) against Peronosclerospora sorghi and Perenosclerospora heteropogoni to develop DM resistant (DMR) maize germplasm with a broad-spectrum of resistance, and identify and further improve new sources of DMR maize germplasm for use in regional breeding programs targeting DM-prone environments. Data indicated that out of 19 DM resistant CMLs, four (CML-433, 465, 466 and 472) were resistant and 15 susceptible to P. sorghi. Screening of new inbred lines from CIMMYT-Asia (CA) resulted in identification of a set of yellow maize lines with good level of DM resistance (disease score – 0.0–25%). However, the high quality protein maize (QPM) lines derived from CIMMYT Population 61 and bi-parental pedigree crosses between elite QPM lines showed very poor resistance to DM. Progenies of the bi-parental population developed by crossing DMR (P. sorghi) CA lines showed further enhanced levels of resistance to both P. sorghi and P. heteropogoni. The study resulted in identification of 10 new inbred lines, in addition to the 4 released CMLs, offering consistent high resistance to both the DM pathogens. Promising bi-parental populations (13) with combined DM resistance and other desirable agronomic traits were identified for the extraction of a new generation of DMR lines with broad-spectrum DM resistance and other commercial traits. Comparison of genotypic response under different screening methods/DM species clearly indicated that the glasshouse-based sandwich method of screening against P. sorghi was the best method for identifying promising genotypes with a high level of DM resistance that were also resistant to DM under field conditions for both the species. However, the highly controlled conditions used for sandwich screening, which is most favourable for disease development, resulted in high disease pressure potentially masking the identification of genotypes with a moderate level of DM resistance.

Two loci in sorghum with NB-LRR encoding genes confer resistance to Colletotrichum sublineolum

The aim of this work was to identify plant resistance genes to the sorghum anthracnose fungus Colletotrichum sublineolum. cDNA-AFLP transcript profiling on two contrasting sorghum genotypes inoculated with C. sublineolum generated about 3,000 informative fragments. In a final set of 126 sequenced genes, 15 were identified as biotic stress related. Seven of the plant-derived genes were selected for functional analysis using a Brome mosaic virus-based virus-induced gene silencing (VIGS) system followed by fungal inoculation and quantitative real-time PCR analysis. The candidate set comprised genes encoding resistance proteins (Cs1A, Cs2A), a lipid transfer protein (SbLTP1), a zinc finger-like transcription factor (SbZnTF1), a rice defensin-like homolog (SbDEFL1), a cell death related protein (SbCDL1), and an unknown gene harboring a casein kinase 2-like domain (SbCK2). Our results demonstrate that down-regulation of Cs1A, Cs2A, SbLTP1, SbZnF1 and SbCD1 via VIGS, significantly compromised the resistance response while milder effects were observed with SbDEFL1 and SbCK2. Expanded genome analysis revealed that Cs1A and Cs2A genes are located in two different loci on chromosome 9 closely linked with duplicated genes Cs1B and Cs2B, respectively. The nucleotide binding-leucine rich repeat (NB-LRR) encoding Cs gene sequence information is presently employed in regional breeding programs.

Adaptation of contrasting cocksfoot plant types to agricultural environments across the Mediterranean basin

Stress-tolerant forage resources are increasingly needed for the environmental and economic sustainability of extensive Mediterranean livestock systems. Perennial forages such as cocksfoot ( Dactylis glomerata L.) can be a valuable alternative to annuals, if they can survive across successive summer droughts. One Mediterranean cultivar of cocksfoot subsp. hispanica with complete summer dormancy (Kasbah), five non-dormant (Delta 1, Jana, Medly, Ottava) or incompletely dormant (Currie) Mediterranean cultivars of subsp. glomerata, and one Continental cultivar (Porto) of subsp. glomerata, were evaluated for dry matter yield over three years and persistence as final plant survival in six sites of Algeria, France, Italy, Morocco and Portugal, with the objectives of: (i) modeling adaptive responses and targeting cultivars as a function of environmental factors associated with genotype × location (GL) interaction; (ii) defining plant ideotypes, adaptation strategies and opportunities of international co-operation for regional breeding programmes. Adaptive responses were modeled by joint regression, additive main effects and multiplicative interaction (AMMI), and factorial regression. The most predictive models were: (i) factorial regression as a function of site spring–summer drought stress (as long-term potential evapotranspiration minus actual water available), for yield; (ii) AMMI including one GL interaction principal component related to site annual and spring–summer drought stress, for persistence. GL interaction of crossover type for yield and persistence was large and mainly associated with the summer dormancy trait. Completely dormant germplasm was specifically adapted to severe drought. Non-dormant Mediterranean cultivars tended to be specifically adapted to moderate drought stress, although they varied to some extent in adaptive response to drought-stress levels. The Continental cultivar was generally misadapted. The completely summer-dormant germplasm also tended to have greater general persistence across locations. Early flowering tended to correlate with higher yield and persistence of the cultivars across locations. Considerations on experimental conditions along with previous physiological studies from three sites suggested that water use efficiency of the cultivars tended to parallel their site-specific yield response. On the whole, the results suggest different adaptation targets, plant types, genetic resources and cultivar recommendation for northern Africa and southern Europe. Summer-dormant material of subsp. hispanica has prevalent interest for northern Africa. Breeding widely adapted, non-dormant or incompletely dormant Mediterranean cultivars of subsp. glomerata has prevalent interest for southern Europe, especially when targeted to moderate crop duration (3–4 years). However, completely summer-dormant germplasm could gain adaptive potential for Mediterranean-climate European regions in the future, to mitigate the effects of the predicted increasing drought due to climate change.

Response of Mediterranean Tall Fescue Cultivars to Contrasting Agricultural Environments and Implications for Selection

Extensive livestock is a basic socio-economic feature of the Mediterranean region whose environmental and economic sustainability depends on the ability of forage resources to withstand climatically stressful conditions. Perennial forages such as tall fescue can be a valuable alternative to annuals, if they can survive across successive summer droughts. Three-year dry matter yield and plant survival of five cultivars of Mediterranean-type tall fescue were evaluated in six sites of Algeria, France, Italy, Morocco and Portugal, with the following objectives: (i) modelling adaptive responses and targeting cultivars as a function of environmental factors associated with genotype × location interaction; and (ii) defining plant ideotypes, adaptation strategies and opportunities for international co-operation for regional breeding programmes. Site mean yield and winter temperatures were positively correlated, whereas sward persistence was positively correlated to lower site heat and drought stress. Cultivar adaptation was adequately modelled by factorial regression as a function of site spring–summer (April–September) drought stress (long-term potential evapotranspiration minus actual water available) for yield, and annual drought stress for final persistence. Specific-adaptation responses to high- or low-stress environments emerged which were consistent with drought-stress levels of cultivar selection environments. However, the wide-adaptation response of cultivar Flecha suggested that breeding for wide adaptation can be feasible.

Adaptation of landrace and variety germplasm and selection strategies for lucerne in the Mediterranean basin

Lucerne ( Medicago sativa L.) can enhance the economic and environmental sustainability of crop-livestock systems in the western Mediterranean basin, but requires improved adaptation to stressful environments because of a predicted shortage of irrigation water and climate change. This study reports on three-year dry matter yields of five landraces from Morocco, Italy and Tunisia and seven varieties from France, Italy, Australia and USA assessed across 10 agricultural environments of Algeria, Tunisia, Morocco and Italy of which four were rainfed, one was continuously irrigated (oasis management), and five were irrigated but adopted a nine-week suspension of irrigation during summer. Our objectives were targeting cultivars to specific environments, and assisting regional breeding programmes in defining adaptation strategies, genetic resources and opportunities for international co-operation. The crop persisted well in all environments, but environment mean yield was strictly associated ( P < 0.01) with annual and spring-summer (April–September) water available. Rainfed cropping implied 42% lower yield with 61% less spring-summer water available relative to irrigation with withheld summer water across three sites hosting both managements. All of these sites showed genotype × management interaction (at least P < 0.10). Cross-over genotype × environment (GE) interaction between top-yielding cultivars occurred across the 10 environments. Total number of harvests (range: 9–23), soil salinity as measured by electrical conductivity (range: 0.20–6.0 dS m −1), and average spring-summer water available (range: 102–932 mm) were selected as significant ( P < 0.05) environmental covariates in a factorial regression model explaining 53% of GE interaction variation. This model was exploited for targeting cultivars as a function of site-specific levels of these factors. Its indications agreed largely with those of an additive main effects and multiplicative interaction model with two GE interaction principal components. An Italian landrace exhibited specific adaptation to severely drought-prone environments, whereas landraces from north Africa were not adapted to such environments. One Moroccan landrace was specifically adapted to high number of harvests (partly reflecting frequent mowing). One variety selected for salt tolerance, and one Moroccan landrace, were specifically adapted to salt-stress environments. Environment classification as a function of GE interaction effects indicated three groups which may be object of specific breeding: (i) rainfed or irrigated environments featuring limited spring-summer water available (<350 mm), nil or low soil salinity, and moderate to low number of harvests; (ii) salt-stress environments; and (iii) environments characterized by high number of harvests.

Characterization of wheat (Triticum aestivumL.) cultivars grown in Lesotho by storage proteins

Thirty bread wheat cultivars grown in Lesotho were analysed with sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). High and low molecular weight glutenin subunits (HMW-GS and LMW-GS) and gliadins were used to determine genetic variability and relationships between the cultivars. The HMW-GS could not distinguish the cultivars, while both LMW-GS and gliadins could. The Glu-1 score showed that all the quality classes from excellent to poor were represented in the material, but 11 cultivars had the highest score of 10, indicating excellent quality. Cluster analysis performed using gliadins in combination with LMW-GS generated dendrograms which segregated cultivars according to genetic distance. However, the genetic distance between the cultivars were so close that it could be concluded that they are from the same gene-pool and have been used several times in regional breeding programmes.