Transgressive segregation and generation mean analysis reveal the gene action underlying the inheritance of drought tolerance in rice

Abstract

Climate change, an effective driver of unprecedented seasonal droughts, is greatly affecting rice production in Africa by threatening food security and safety. Rice, one of the major staple crops on the continent, can save the situation through the development of drought-tolerant cultivars, presenting a major challenge for future rice improvement programs as drought is regarded as a critical limitation in rain-fed ecosystems. This study sought to understand the genetic basis and inheritance behind the expression of tolerance of rice breeding lines to droughtstress through generation mean analysis. To achieve these objectives, two drought-sensitive genotypes (Jasmine 85 and CRI-Agrarice) were crossed with a drought-tolerant genotype (APO) to develop six populations (F1, F2, BC1, BC2, P1 and P2) under screenhouse drought-stress and non-stress evaluation. Data were collected on grain yield and yield-related traits among which the generation mean analysis was conducted. At least one transgressive phenotype was produced in the F2 population for each trait whether there is a significant difference or not among the parental lines under drought-stress. Under non-stress conditions, there was a significance for all six types of gene action for days to flowering in both crosses. Among both crosses and water-regimes, additive x additive gene interaction was significant for most of the traits even though the scaling tests were not significant indicating the effectiveness of selection in early generations. Therefore, either forward breeding or backcross breeding can be adopted as breeding strategies for rapid improvement for these lines to drought tolerance.