|Klein, Robert - Bob|
Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2006
Publication Date: 12/14/2006
Citation: Harris, K., Borrell, A., Jordan, D., Rosenow, D., Nguyen, H., Klein, P., Klein, R.R., Mullet, J. 2007. Sorghum stay-green QTL individually reduce post-flowering drought-induced leaf senescence. Journal of Experimental Botany. 58:327-338. Interpretive Summary: Major advancements in science hinge on the identification of genes controlling plant and animal traits that are critically important to agriculture. Genes are tiny packets of genetic blueprint material that are found inside the cells of all plants and animals and control all of the physical characteristics of these organisms. Our work focuses on improving major grain crops and, with gene sequences, the genetic blueprint will be visible and this information can make improving the plants more efficient. This study is a detailed physiological analysis in sorghum of individual stay-green genes, which control post-flowering drought tolerance in cereal crops. The comparison of the different stay-green genes and surrounding genes on drought resistance will permit more efficient identification and understanding of the function of these genes, and will allow scientists to understand those key features of the genetic blueprint that make sorghum adapted to arid growing conditions. Information will be primarily used by fellow scientists but the work will ultimately result in better adapted, higher producing crop varieties available to American farmers.
Technical Abstract: Sorghum is an important source of food and feed, especially in the semi-arid tropics because this cereal is well adapted to harsh, drought-prone environments. Post-flowering drought adaptation in sorghum is associated with the stay-green phenotype. Alleles that contribute to this complex trait have been mapped to four major trait loci, Stg1–Stg4. Near-isogenic lines, containing DNA spanning one or more of the four stay-green trait loci were constructed. The size and location of stay-green DNA regions in each Near-isogenic line were analyzed using DNA markers spanning the four stay-green regions. Near-isogenic lines were identified that contained DNA completely or partially spanning Stg1, Stg2, Stg3, or Stg4. Near-isogenic lines were also identified that contained sub-portions of each trait locus and various combinations of the four major stay-green trait loci. Near-isogenic lines containing Stg2 retained more green leaf area at maturity under terminal drought conditions than non-Stg2 lines. Under post-anthesis water deficit, a trend for delayed onset of leaf senescence was also exhibited by the Stg2, Stg3, and Stg4 Near-isogenic lines. Significantly lower rates of leaf senescence were displayed by all of the Stg Near-isogenic lines to varying degrees, but particularly by Stg2. Greener leaves at anthesis were exhibited by the Stg1 and Stg4 Near-isogenic lines. The genetic lines created in this study provide the starting point for in-depth analysis of stay-green physiology, interaction among stay-green trait loci and map-based cloning of the genes that underlie drought resistance in sorghum.