Genetic background variability influences novel ARS grain sorghum productivity and resource partitioning

Abstract A recent focus for sorghum [ Sorghum bicolor (L.) Moench] improvement deals with the introgression of multi-seed ( MSD ) alleles into genetic backgrounds by leveraging genomic tools and combining it with the stay-green trait to improve yield potential and stability in resource-limited environments. A key challenge in these efforts is optimizing resource partitioning and efficiently allocating assimilates and nutrients to reproductive structures without compromising seed development or plant resilience. We conducted two complementary experiments: a two‑year evaluation under optimal irrigation to establish baseline genotype performance (2023–2024), followed by a single‑year exploratory multi‑level irrigation experiment to assess early responses to water limitation (2024). Two inbred parental lines (BTx399 and RTx430) and four near-isogenic lines (NILs) derived from parentals by back cross introgression of two different mutant genes msd1-2 and msd2-1 were used to investigate how genetic variation influences resource allocation in grain sorghum grown under variable environmental and irrigation conditions. Between the parental lines and corresponding progenies, the BTx399 pedigrees consistently produced stable and high yields, whereas RTx430 pedigrees fluctuated from year to year, showing it is more sensitive to marginal conditions and less efficient at producing grain when stressed. Genotypes carrying msd1 alleles are associated with higher yield stability under water deficit compared to msd2 alleles. Our findings also suggest that MSD1 influences nutrient allocation independent of jasmonic acid (JA) activity. Overall, the findings reinforce that stable resource assimilation and allocation are critical in achieving yield stability in grain sorghum, providing a physiological basis for selecting genotypes suited to resource-limited environments.