Cross-genera marker transferability, expression dynamics and in silico identification of rice seed size gene orthologs in contrasting groundnut genotypes.

BACKGROUND

Seed size is an important component of groundnut productivity, market value and end-use quality. However, the molecular mechanisms underlying variation in seed size remain insufficiently characterized in groundnut. The present study aimed to identify putative candidate genes associated with seed-size variation using a comparative genomics approach based on rice seed-size-related genes.

METHODS AND

RESULTS

Thirty diverse groundnut (Arachis hypogaea L.) genotypes were evaluated at the Dryland Farm, Regional Agricultural Research Station (RARS), Tirupati, during Kharif 2022. Analysis of variance revealed significant variation for hundred pod weight, hundred kernel weight, kernel length and kernel breadth. Based on seed size, Bheema (TG 47) and TPT 4 (TCGS 30) were selected as contrasting genotypes. Developing kernels collected at 60 and 85 days after sowing (DAS) were subjected to semi-quantitative PCR analysis using primers targeting eight rice seed-size-related genes. All eight genes were amplified and exhibited differential expression between the contrasting genotypes and developmental stages. GW5, GW7, GS3 and GS2 showed comparatively higher expression in the bold-seeded genotype at 60 DAS and were identified as promising candidate genes. In silico analysis using PeanutBase identified 31 putative homologous sequences corresponding to rice seed-size-related genes, while NCBI transcriptome searches identified 32 putative homologous groundnut transcripts.

CONCLUSIONS

The differential expression of GW5, GW7, GS3 and GS2 provides preliminary evidence for their potential involvement in seed-size variation in groundnut. These genes represent promising comparative candidate genes for further validation through sequence characterization, peanut-specific primer development, quantitative expression analysis and genetic association studies.