Drought tolerance is an important agronomic trait in field crops, but the genetic and physiological mechanisms that condition its expression are not well understood. Sorghum (Sorghum bicolor (L.) Moench) is one of the more drought tolerant crops and is an excellent model for studying mechanisms of drought tolerance in higher plants. The purpose of the studies presented in this report was to use molecular markers to identify genetic loci associated with the expression of pre-flowering and post-flowering drought tolerance in sorghum. A recombinant inbred line population of 100 lines was developed from a cross between two parents with contrasting drought tolerance, TX7078 (pre-flowering tolerant, post-flowering susceptible) and B35 (post-flowering tolerant, pre-flowering susceptible). The RI lines were agronomically evaluated under conditions of pre-flowering drought, post-flowering drought, and under full irrigation. The population was also genotyped with 170 molecular markers using standard protocols. Analysis of genotypic and phenotypic data led to identification of regions of the genome associated with specific drought tolerance reactions. We identified quantitative trait loci (QTLs) for yield stability, yield under drought, stay-green, and other traits associated with drought tolerance. We developed and characterized near isogenic lines with contrasting alleles for markers linked to individual QTL and verified the marker-phenotype association observed in the RI lines. We conclude that our approach of narrowing on specific genomic regions associated with drought tolerance, coupled with physiologic characterization, holds promise for developing a better understanding of this complex trait.

English

0101|AL-ABC Program|AGRIS 0101

Jose Juan Caballero

CIMMYT Publications Collection