Quantitative trait loci for sorghum maturity and their influence on agronomic traits in diverse growing environments
Abstract
Maturity is a critical trait for better adaptation and productivity of sorghum (Sorghum bicolor L. Moench) in stress environments where this crop is usually grown. Despite accrued knowledge of how genotypes with different maturity respond to environments, breeding efficiency is still limited by poor characterization of individual quantitative trait loci (QTL) affecting this trait. The objective of this research was to identify factors of sorghum maturity through DNA marker association, and to determine their relationships with other important agronomic traits. The 10% earliest and 10% latest maturing sorghum lines were identified in FGxM90812 (Cross 1) and MMxSEPON72 (Cross 2). Parents and progeny were evaluated at one temperate location in the US and six semi-arid tropical locations in Niger. For each cross, maturity (days to anthesis), plant height, and grain yield data were statistically analyzed considering six alternative groupings of locations. Genetic variability for maturity and plant height was high. For grain yield however there was significant genetic variability only in Cross 2 under rainfed conditions of Niger. Seventy-three random amplified polymorphic DNA (RAPD) and six simple sequence repeat (SSR) markers in Cross 1, and 62 RAPD markers in Cross 2, were used in single marker analyses. In Cross 1, 17 of the 79 markers (22%) detected maturity loci with stable expression across environments. Most of these markers also identified plant height factors in all environments, but grain yield and maturity were related only when the temperate location was included. In Cross 2 four markers out of 62 (6%) detected maturity factors in all environmental settings. In this cross, maturity influenced plant height and grain yield especially under rainfed conditions in Niger. A set of 121 recombinant inbred lines (RIL) independently developed from Cross 1 was used to confirm association of six of the above DNA markers with maturity factors. Four RAPD and two SSR collectively explained 47% of the phenotypic variation for maturity in the RIL. They mapped to one genomic segment defining the position of a putative QTL for maturity in sorghum.
Degree
Ph.D.
Advisors
Axtell, Purdue University.
Subject Area
Agronomy|Genetics|Molecular biology|Botany|Plant propagation
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