Multiple interval mapping of QTLs and epistasis for iron toxicity tolerance in segregating population of Indica rice

Abstract

The global average temperature has increased by approximately 0.5 °C, over a last few decades and is projected to continue to increase. Environmental stress factors such as, elevated temperature, salinity, toxic elements (Fe, Al, Cd, Cr, Pb, Zn and As), drought and rising CO2 affect plant growth and make a growing threat to agriculture. Rice is a primary food crop in the world and the establishment of rice crop in acidic soil and in marginal soil is a major goal for the improvement of rice production to fulfill the food security. Among environmental stresses, Fe2+ toxicity is one of the main stresses in limiting the cereal crops production. Tolerant rice genotypes that can tolerate the high concentration of Fe2+ toxicity are the potential source genes for rice tolerance improvement in Fe2+ toxicity. In this research work, the genetic basis of seed germination traits and growth traits was investigated in rice using (multiple interval mapping) MIM. Many rice genotypes serve as source of tolerant against toxic metal ion like Fe2+, could be an important factor in controlling the sever effect of Fe2+ toxicity on germination and seedling growth traits. The F3 progenies of cross between Fe2+ toxicity tolerant cultivar ‘Pokkali’ and susceptible cultivar ‘Pak basmati’ were test against the optimized level of Fe2+ toxicity at germination, to determine the mode of inheritance to Fe2+ toxicity tolerance. Wide range of continues variation was found in F3 progenies. Among the 49 quantitative germination trait and 23 growth trait loci (QTLs) on chromosomes 1, 2, 4, 6, 8 and 9 linked with tolerance to Fe2+ toxicity was mapped. Additionally, 21 QTLs for germination traits and 9 QTLs for growth traits were classified as major QTLs using MIM. For germination and growth traits, notable epistasis between the chromosome 1, 2, 4, 6 and 11 was detected across germination and growth traits. Our results suggest that the tolerance mechanisms at germination and seedling phases could differ for Fe2+ toxicity. QTLs detected in this study for germination and seedling growth could be a source of new alleles for development of tolerance rice to Fe2+ toxicity varieties and transformation, gene cloning and gene editing in the future