Analysis of drought tolerance in sorghum: Quantitative trait loci mapping and evaluation of near-isogenic lines
Abstract
Drought is the primary limitation to crop production in the world today. The use of crops that are tolerant to drought may provide a solution to this problem. Progress in developing drought tolerant crops has been slow because the genetic and physiological mechanisms that mediate tolerance are poorly understood. We have used sorghum (Sorghum bicolor L. (Moench)) as a model to identify mechanisms that condition tolerance to drought during the pre-flowering and post-flowering developmental stages. A set of 98 recombinant inbred (RI) sorghum lines was developed from two inbreds with contrasting drought reactions: TX7078 (pre-flowering drought tolerant/post-flowering drought susceptible) and B35 (pre-flowering drought susceptible/post-flowering drought tolerant). The RI lines were characterized for agronomic performance in pre-flowering and post-flowering drought environments. This evaluation indicated segregation for drought tolerance during these two developmental stages. The RI lines were genotyped using 150 RAPD and 20 RFLP markers. Markers were ordered into a genetic map by linkage analysis and were used to identify quantitative trait loci (QTL) associated with drought tolerance. Several regions of the genome were shown to be associated with the expression of pre-flowering and/or post-flowering drought tolerance. Near-isogenic lines (NIL) contrasting at specific loci were developed to evaluate the expression of individual QTL. Molecular markers linked to specific QTL were used to identify and select NIL from $\rm F\sb{5:8}$ heterogeneous inbred families. These NIL were evaluated in drought and non-drought environments to determine the phenotype associated with each drought tolerance locus. The analysis of NIL has confirmed the expression of at least five QTL associated with agronomic performance in drought environments.
Degree
Ph.D.
Advisors
Ejeta, Purdue University.
Subject Area
Genetics|Molecular biology|Agronomy
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