Stemphylium blight (caused by Stemphylium botryosum Wallr.) is one of the major diseases of lentil (Lens culinaris Medik.) in South Asia and North America. The objective of the study was to identify linkage map position of the genes conferring resistance to stemphylium blight and the markers linked to the genes for its utilization in marker‐assisted breeding. A population of 206 F7–derived recombinant inbred lines (RILs) was developed from a cross between ILL‐6002 (resistant) and ILL‐5888 (susceptible). The RILs were planted in disease‐screening plots at Ishurdi, Bangladesh in the 2006–2007 and 2008–2009 winter cropping seasons. Significant variation was detected among RILs for disease scores and frequency distributions suggested complex inheritance. An intraspecific linkage map was constructed that comprised 139 markers; 21 simple sequence repeats (SSR), 27 randomly amplified polymorphic DNA (RAPD), 89 sequence related amplified polymorphism (SRAP) markers and 2 morphological markers distributed over 14 linkage groups. One significant quantitative trait loci (QTL) was detected based on disease scores from the 2006–2007 experiment while three significant QTLs were detected from the 2008–2009 experiment. The QTL QLG480–81 was common in both years and accounted for 25.2 and 46.0% of the variation of disease scores in 2006–2007 and 2008–2009 experiments, respectively. Two SRAP markers, ME5XR10 and ME4XR16c, and one RAPD marker, UBC34, located on linkage group 4, were significantly associated with the QLG480–81 in both crop years. After validation, the more tightly linked ME4XR16c marker may be used for marker assisted selection for stemphylium blight resistance.

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Drought is one of the major abiotic stresses limiting lentil productivity in rainfed production systems. Specific rooting patterns can be associated with drought avoidance mechanisms that can be used in lentil breeding programs. In all, 252 co-dominant and dominant markers were used for Quantitative Trait Loci (QTL) analysis on 132 lentil recombinant inbred lines based on greenhouse experiments for root and shoot traits during two seasons under progressive drought-stressed conditions. Eighteen QTLs controlling a total of 14 root and shoot traits were identified. A QTL-hotspot genomic region related to a number of root and shoot characteristics associated with drought tolerance such as dry root biomass, root surface area, lateral root number, dry shoot biomass and shoot length was identified. Interestingly, a QTL (QRSratio IX-2.30 ) related to root-shoot ratio, an important trait for drought avoidance, explaining the highest phenotypic variance of 27.6 and 28.9% for the two consecutive seasons, respectively, was detected. This QTL was closed to the co-dominant SNP marker TP6337 and also flanked by the two SNP TP518 and TP1280. An important QTL (QLRN ) related to lateral root number was found close to TP3371 and flanked by TP5093 and TP6072 SNP markers. Also, a QTL (QSRL ) associated with specific root length was identified close to TP1873 and flanked by F7XEM6b SRAP marker and TP1035 SNP marker. These two QTLs were detected in both seasons. Our results could be used for marker-assisted selection in lentil breeding programs targeting root and shoot characteristics conferring drought avoidance as an efficient alternative to slow and labor-intensive conventional breeding methods.

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Agromorphological traits have immense importance in breeding lentils for higher yield and stability. We studied the genetics and identified map positions of some important agro-morphological traits including days to 50% flowering, plant height, seed diameter, 100 seed weight, cotyledon color, and growth habit inLens culinaris. Earlier developed RILs for stemphylium blight resistance (ILL-5888 × ILL-6002), contrasted for those agro-morphological traits, were used in our study. Three QTLs for days to 50% flowering were detected with additive and epistatic effects. One QTL for days to 50% flowering, QLG483(QTL at linkage group 4 at 83 cM position), accounted for an estimated 20.2% of the variation, while QLG124 × QLG1352and QLG484 × QLG138accounted for 15.6% and 24.2% of the variation, respectively. Epistatic effects accounted for most of the variation in plant height, but the main effect of one QTL, QLG84, accounted for 15.3%. For seed diameter, three QTLs were detected, and one QTL, QLG482, accounted for 32.6% of the variation. For 100 seed weight, five QTLs were identified with significant additive effects and four with significant interaction effects. The main effect of one QTL, QLG482, also accounted for 17.5% of the variation in seed diameter. QLG482-83which appears to affect days to 50% flowering, seed diameter, and 100 seed weight is flanked by RAPD markers, UBC 34 and UBC1. Growth habit and cotyledon color are controlled by single genes with prostrate dominant to erect and red cotyledon dominant to yellow. The QTL information presented here will assist in the selection of breeding lines for early maturity, upright growth habit, and improved seed quality.

Genotyping of lentil plant genetic resources holds the promise to increase the identification and utilization of useful genetic diversity for crop improvement. The International Center for Agriculture Research in the Dry Areas (ICARDA) lentil reference set plus collection of 176 accessions was genotyped using genotyping-by-sequencing (GBS) and 22,555 SNPs were identified. The population structure was investigated using Bayesian analysis (STRUCTURE, k = 3) and principal component analysis. The two methods are in concordance. Genome-wide association analysis (GWAS) using the filtered SNP set and ICARDA historical phenotypic data discovered putative markers for several agronomic traits including days to first flower, seeds per pod, seed weight and days to maturity. The genetic and genomic resources developed and utilized in this study are available to the research community interested in exploring the ICARDA reference set plus collection using GWAS.

Dry pea (Pisum sativum L.) is grown as human and animal feed throughout the world. Large yield losses in pea due to biotic and abiotic stresses compel an improved understanding of mechanisms of stress tolerance and genetic determinants conditioning these tolerances. The availability of stably expressed reference genes is a prerequisite for examining differential gene expression. The objective of this study was to examine the expression profile of several candidate reference genes across a broad range of commercial pea cultivars. Expression profiles of five candidate reference genes; 18s rRNA, actin, TIF, β tubulin-2 and β tubulin-3 were examined. Relative quantifications of candidate reference genes were estimated from control plants, plants after 48 h of cold treatment, and plants 24 and 48 h after inoculation with Sclerotinia sclerotiorum, the causal agent of white mold disease of pea. RT-qPCR was performed on cDNA synthesized from three food grade spring peas, Ariel, Aragorn, and Sterling, and two spring yellow peas, Delta and Universal, which are used as animal feed. Analysis of variance (ANOVA) of C T values demonstrated significant variation between varieties and treatments under cold and disease conditions. The most abundant transcripts among tested reference genes were for 18s rRNA. Stability analysis indicated that TIF and β tubulin-3 genes were the most stably expressed candidate genes under both cold and disease stress and could serve as reference genes across a wide range of pea cultivars.