[en] Seed size is key agronomic factor and has been utilised for improvement of pod yield and confectionary trait in groundnut. Seed size is a polygenic trait and little is known about the mechanism of groundnut seed size development. A large seed mutant, TG 89 with 54% greater seed size was identified through an electron beam mutagenesis of a popular groundnut variety,TG26. Present study was undertaken to identify genomic locations for large seed trait in groundnut. Large seed mutant TG 89 was hybridized with a normal seed genotype ICGV 15007. A F2 mapping population with 124 plants was utilized for phenotyping for seed size. About 1431 Transposable element markers (TE) and simple sequence repeat (SSR) markers were employed for genotyping of this population. The linkage mapping and QTL identification was carried out using QTL IciMapping ver 4.1. Out of 1431 molecular markers screened, 83 markers were found polymorphic between TG 89 and ICGV 15007. Bulk segregant analysis with these markers revealed that three markers (Ah1TC3A12, TE 333 and TE 278) had a putative association with the mutant large seed trait. In order to map the genomic regions associated with seed size, F2 mapping population was genotyped with 64 polymorphic TE and 19 SSR markers. These markers were mapped on to the 14 linkage groups covering map distance of 1053 cM. The QTL analysis revealed a major QTL for the mutant large seed trait between flanking markers AhTE333 and AhTE810 in Arahy.05 chromosome with 13% PVE for the seed size. This QTL was located within map interval of 4.7 cM that corresponds to 16.6 Mbp of genomic fragment which harbours an ortholog of BIG SEEDS 1 gene. Quantitative RT PCR revealed downregulation of this BIG SEEDS 1 gene in the mutant indicating probable loss of function mutation in this gene. Current study identified a major QTL on Arahy.05 chromosome and provided a valuable information for candidate gene identification for large seed trait in groundnut. (author)

[en] Gamma ray based-induced mutagenesis has played a significant role in genetic improvement of groundnut. Sustained mutation breeding efforts at BARC, Mumbai, have evolved several improved Trombay groundnut (TG) varieties that have been commercialized across the country. In continuation, a new mutant was developed by gamma ray mutagenesis of cultivar TG 38. This mutant showed an improvement in pod, kernel size and percentage of three-seeded pods. Molecular markers distinguished TG 73 from its parent TG 38 or the check variety, TAG 24. In order to test its suitability and adaptability in different agro-ecological situations, TG 73 was evaluated in multi-location trials over the years in collaboration with Junagadh Agricultural University (JAU), Junagadh, Gujarat, and Dr. Panjabrao Deshamukh Krishi Vidyapeeth (PDKV), Akola, Maharashtra, during summer. In these trials, TG 73 recorded a mean pod yield of 2541 kg/ha and 3218 kg/ha with a superiority of 16.6% and 14.3% over the best check variety, respectively. Based on consistent greater pod yields, TG 73 has been released and notified as TAG 73 and GG 37 for summer cultivation for Maharashtra (Vidharbha region) and Gujarat, respectively. (author)

[en] Electron beam accelerators are being used for many industrial applications including food and agriculture. A 10 MeV linear accelerator facility was standardized for low dose application 0.1–1 kGy) in pulse mode using unscanned scattered beam for irradiation of groundnut seeds for mutation breeding. Using this facility, 50% growth reduction (GR_5_0) dose was standardized in five groundnut genotypes. There were significant differences for radio-sensitivity among these genotypes. Seed mutagenesis of two groundnut genotypes, TG 26 and TG 68 with electron beam has generated one large seeded and four high yielding mutants in preliminary field trials. - Highlights: • A linear electron beam accelerator was standardized for low dose application like seed irradiation. • Real time dose in pulse mode was calibrated with standard dosimetry system. • Differential radio-sensitivity was detected among five groundnut genotypes. • Seed mutagenesis of groundnut has generated four high yielding and one large seed mutants.