Association mapping for image‐based root traits in tropical maize under water stress in semi‐arid regions

Abstract

AbstractThe root system is an organ that indicates signs of stress when a plant is subjected to water‐deficit conditions. However, its assessment is challenging. An alternative has been to obtain variables through image processing. In this way, it allows the rapid evaluation of genetic diversity panels. It contributes to identifying genomic regions or genes associated with the expression of the root system under water‐deficit conditions. Hence, a public diversity panel of 360 inbred lines of maize was evaluated under well‐watered (WW) and water stress (WS) conditions. Roots were phenotyped through image‐based processing. Then, genome‐wide association studies were conducted in WW and WS for each trait, using the Fixed and random model Circulating Probability Unification method. We found 23 genes or genomic regions with significant associations, of which eleven are exclusive to the WW condition, seven to the WS condition, and four are simultaneously associated with both WW and WS. All genomic regions related to the root system in the WS condition are associated with physiological mechanisms and molecular responses related to tolerance to water‐deficit conditions that can be explored in subsequent studies and by breeding programs to obtain varieties that are more tolerant and water efficient to this condition.