Breeding for higher yield and wider adaptability are major objectives of soybean crop improvement. In the present study, 68 advanced breeding lines along with seven best checks were evaluated for yield and attributing traits by following group balanced block design. Three blocks were constituted based on the maturity duration of the breeding lines. High genetic variability for the twelve quantitative traits was found within and across the three blocks. Several genotypes were found to outperform check varieties for yield and attributing traits. During the same crop season, one of the promising entries, NRC 128,was evaluated across seven locations for its wider adaptability and it has shown stable performance in Northern plain Zone with > 20% higher yield superiority over best check PS 1347. However, it produced 9.8% yield superiority over best check in Eastern Zone. Screening for waterlogging tolerance under artificial conditions revealed that NRC 128 was on par with the tolerant variety JS 97–52. Based on the yield superiority, wider adaptability and waterlogging tolerance, NRC 128 was released and notified by Central Varietal Release Committee (CVRC) of India, for its cultivation across Eastern and Northern Plain Zones of India.

Presence of Kunitz trypsin inhibitor (KTI) in soybean seeds necessitates pre-heat treatment of the soy-flour for its inactivation before using it in food and feed products. The heat treatment not only enhances processing costs of the soy-based foods and feeds but also affects seed-protein quality and solubility. Genetic elimination of KTI is an important and effective approach. Therefore, molecular marker-assisted backcross breeding (MABB) approach was adopted for genetic elimination of KTI from two popular soybean genotypes, DS9712 and DS9814. PI542044, an exotic germplasm line was used as donor of the kti allele which inhibits functional KTI peptide production. Foreground selection for the kti allele was performed with three closely linked SSR markers while background selection was done with 93 polymorphic SSR markers. Plants in the BC1F1 generation were found to recover 70.4–87.63 % and 60.26–73.78 % of the recurrent parent genome (RPG) of DS9712 and DS9814, respectively. Similarly, selected plants in the BC2F1 generation had 93.01–98.92 % and 83.3–91.67 % recovery of their respective RPGs. Recombinant selection was performed so as to identify plants with minimal linkage drag. Biochemical analysis of the seeds of the selected plants (ktikti) confirmed absence of KTI peptides in the seeds. Phenotypically, the selected plants were comparable to the respective recurrent parent in yield and other traits. MABB approach helped in speedy development of 6 KTI free breeding lines of soybean. Such lines will be suitable for the farmers and the soybean industries to use in production of soy-based foods and feeds without pre-heat treatment of the soy-flour. It would contribute towards wider acceptability of soy-based foods and feeds.

Background: In this study, whole genome re-sequencing of rust resistant soybean genotype EC241780 was performed to understand the genomic landscape involved in the resistance mechanism. Methods: A total of 374 million raw reads were obtained with paired-end sequencing performed with Illumina HiSeq 2500 instrument, out of which 287.3 million high quality reads were mapped to Williams 82 reference genome. Comparative sequence analysis of EC241780 with rust susceptible cultivars Williams 82 and JS 335 was performed to identify sequence variation and to prioritise the candidate genes. Results: Comparative analysis indicates that genotype EC241780 has high sequence similarity with rust resistant genotype PI 200492 and the resistance in EC241780 is conferred by the Rpp1 locus. Based on the sequence variations and functional annotations, three genes Glyma18G51715, Glyma18G51741 and Glyma18G51765 encoding for NBS-LRR family protein were identified as the most prominent candidate for Rpp1 locus. Conclusion: The study provides insights of genome-wide sequence variation more particularly at Rpp1 loci which will help to develop rust resistant soybean cultivars through efficient exploration of the genomic resource.

Nested association mapping (NAM) captures the best features of both linkage and association mapping and enables the high power and high resolution of quantitative trait locus mapping through joint linkage-association analysis. In the current study, NAM population was developed by hybridizing JS 335, a popular variety of central India with 20 diverse soybean genotypes. The parents used in the study have various traits of economic importance such as drought and water-logging tolerance, bacterial pustule and yellow mosaic virus resistance, wider adaptability, resistance to mechanical damage and higher yield potential. High variability in the F₂populations of 20 crosses for grain yield and days to maturity indicated scope for development of high-yielding varieties. Genetic variability studies, correlation, regression, principal component analysis (PCA) and genetic diversity analyses were carried out in 900 NAM-recombinant inbred lines (RILs) derived from 11 crosses. Correlation and regression analysis indicated a significant positive effect of biomass, pods/plant, harvest index, branches/plant, nodes/plant and plant height on grain yield. Genetic diversity analysis grouped 900 NAM-RILs into 10 clusters. PCA revealed first two principal components to explain 63.78% of total variation mostly contributed by grain yield, biomass and number of pods. The inbred lines developed in this study will serve as an elite soybean genetic resource in understanding the genetic architecture underlying different traits of economic significance.