Mapping Heat Resilience: Parental Polymorphism Study in Contrasting Rice (Oryza sativa L.) Genotypes Using Micro Satellite Markers

Aims: The study aims to investigate temperature tolerance in rice by assessing the polymorphism in microsatellite (SSR) marker segregation between heat sensitive recipient parent (KAU Manu Ratna) and heat tolerant donor parent (Nagina 22).

Place and Duration of Study: Department of Plant Physiology, College of Agriculture, Kerala Agricultural University, Vellanikkara, Thrissur, Kerala, India between January to April, 2022.

Methodology: The rice genotypes namely KAU Manu Ratna (susceptible recipient parent) and Nagina 22 (tolerant donor parent) exhibiting contrasting response to heat stress tolerance were used for the study. Leaf samples collected from 25-day old seedlings were used for DNA extraction. A set of previously identified 44 heat tolerance Rice Micro satellite (RM) markers spanning across the 12 chromosomes of rice were used for the parental polymorphism study. The DNA fragments were amplified by polymerase chain reaction using RM markers, followed by agarose gel electrophoresis. The amplified DNA fragments were documented using gel documentation system and polymorphism patterns were analyzed.

Results: The result of the genetic polymorphism survey between the rice genotypes Nagina 22 (heat-tolerant) and KAU Manu Ratna (heat-sensitive) revealed that 20 markers out of 44 SSR markers employed in the study were found to be polymorphic between the two genotypes. A polymorphism of 45.45% highlights the genetic diversity between the parental lines, providing essential markers for mapping QTLs linked to traits conferring heat stress tolerance in rice and strengthen the heat stress marker assisted breeding programmes.

Conclusion: The study highlights the potential of micro satellite marker analysis in identifying genetic polymorphisms between heat-tolerant and heat-sensitive rice genotypes. The findings pave way to strengthen marker-assisted breeding strategies, especially by enabling precise delineation of QTLs conferring heat-stress tolerance. The results thus offer a strong foundation for developing climate resilient rice cultivars to address the challenges of climate induced heat stress on global food security.