Genetic analysis of field and physiological indicators of drought tolerance in bread wheat (Triticum aestivum L.) using diallel mating design

In order to study the inheritance of field, physiological and metabolite indicators of drought tolerance in wheat, an eight-parental diallel cross, excluding reciprocals, was grown in a randomized complete block design (RCBD) with three replications under two different water regimes (irrigated and rainfed). Significant differences were found for yield potential (Yp), stress yield (Ys), stress tolerance index (STI), leaf water potential (LWP), relative water content (RWC), water use efficiency (WUE) and evapotranspiration efficiency (ETE). Yp, RWC and evapotranspiration efficiency (ETE) showed highly significant differences for both general combining ability (GCA) and specific combining ability (SCA), indicating the involvement of both additive and non-additive gene action in their inheritance. Ys, STI and WUE revealed highly significant differences for SCA, hence non-additive gene action was predominant for these traits. The best general combiners with positive effects, for improvement of Yp, Ys, STI, LWP, RWC, WUE and ETE under drought conditions were parents 5, 1, 6, 2, 7, 1 and 2, respectively. The best specific combination with heterobeltiosis over the best parents for improvement of Yp, Ys, STI, LWP, RWC, WUE and ETE were crosses 3 × 6, 2 × 4, 2 × 6, 5 × 8, 2 × 6, 2 × 4 and 1 × 7, respectively indicating that parents of these crosses are genetically diverse. High broad-sense heritability observed for all the traits confirmed that all the traits are more genetic, but because of low narrow-sense heritability the rule of additive part was low.Key words: Drought tolerance, physiological indicators, diallel mating design, genetic analysis

Potential new genes for resistance to Mycosphaerella graminicola identified in Triticum aestivum x Lophopyrum elongatum disomic substitution lines.

Lophopyrum species carry many desirable agronomic traits, including disease resistance, which can be transferred towheat by interspecific hybridization. To identify potentially new genes for disease and insect resistance carried by individual Lophopyrum chromosomes, 19 of 21 possible wheat cultivar Chinese Spring 9 Lophopyrum elongatum disomic substitution lines were tested for resistance to barley yellow dwarf virus (BYDV), cereal yellow dwarf virus (CYDV), the Hessian fly Mayetiola destructor, and the fungal pathogens Blumeria graminis and Mycosphaerella graminicola (asexual stage: Septoria tritici). Low resistance to BYDV occurred in some of the disomic substitution lines, but viral titers were significantly higher than those of two Lophopyrum species tested. This suggested that genes on more than one Lophopyrum chromosome are required for complete resistance to this virus. A potentially new gene for resistance to CYDV was detected on wheatgrass chromosome 3E. All of the substitution lines were susceptible to Mayetiola destructor and one strain of B. graminis. Disomic substitution lines containing wheatgrass chromosomes 1E and 6E were significantly more resistant to M. graminicola compared to Chinese Spring. Although neither chromosome by itself conferred resistance as high as that in the wheatgrass parent, they do appear to contain potentially new genes for resistance against this pathogen that could be useful for future plant-improvement programs

QTL analysis of seed size and yield-related traits in an inter-genepool population of common bean (Phaseolus vulgaris L.)

Quantitative trait locus (QTL) analysis of seed size and yield-related traits provide useful information to contribute to breeding programs. A recombinant inbred line population composed of 100 lines from a cross of Goli cultivar and breeding line AND1007 was grown in field and greenhouse conditions to identify QTLs controlling the important primary traits affecting seed size and yield-related traits. A linkage map consisting of 240 SNPs, spanning ∼520 cM of common bean genome was used for QTL mapping. A total of 39 QTLs were identified on different chromosomes, which explained 5 to 32–32 % of the phenotypic variance for the measured traits. Thirty-one of them had only individual effects, six were only involved in three epistatic interactions and two had both individual and epistatic effects. Most of the positive alleles for seed size traits and number of seeds per pod originated from the Andean parent (AND1007) while the alleles related to number of pod and seeds per plant originated from Mesoamerican parent (Goli). QTLs for seed weight, seed length and seed yield co-localized on the Pv09, suggesting these traits may be controlled by QTLs that are linked together or have pleiotropic effects. A major QTL was found for seed length (SL9.1GA) which explained ∼32 % of the phenotypic variance and had repeatability over field and greenhouse trials. Overall, results showed that QTLs with single-locus additive and epistatic effects were involved in the control of bean seed size and yield-related traits while the effects of epistatic interactions were smaller than single-locus QTLs

Grain Yield, Its Components, Genetic Diversity and Heritability in Chickpea (Cicer arietinum L.)

The current research was carried out to investigate grain yield and components and their genetic diversity and heritability of some important agronomic traits, in 19 chickpea genotypes, based on a randomized complete block design with 3 replications in Research Field of Bu-Ali Sina University, Hamadan, Iran in 2011-2012 growing seasons. The ANOVA results showed that, there were highly significant differences (p < 0.01) among genotypes for the SPAD number, number of sub-branch per plant, pod number per plant, 100-kernel weight, grain yield, biological yield, and harvest index. The mean comparisons results indicated that the genotypes 14, 12, 4 and 19 (with 234.7, 240, 250.3 and 259.4 kilogram of grain yield per ha, respectively) and the genotypes 18, 8, 15, and 6 (with 151.01, 167.6, 167.8 and 189 kilogram of grain yield per ha, respectively) had the maximum and minimum economic yield, respectively. According to phonotypical correlation results, there were positive and significant (p < 0.01) correlations between grain yield and pod number per plant (0.623**), plant height (0.432**), harvest index (0.425**) and biomass (0.349**). Step-wise regression indicated that the pod number per plant, harvest index, biomass, number of sub-branch per plant, and plant height were the most effective traits on economic yield and they explained 84.68 percent of the variation in economic yield. Furthermore, harvest index and seed number per plant had the maximum and minimum heritability, respectively, indicating that they could be hired as sources of variation for improving the grain yield and selecting superior genotypes