1a. Objectives (from AD-416):
(1) To characterize selected germplasm lines of sorhgum for response to cold stress at early season and other specified stages of development. (2) To identify additional germplasm resources for enhanced cold tolerance breeding programs in different types of sorghums. (3) To assemble phenotypic and DNA marker information that can be applied towards accelerated development of cold-tolerant sorghum germplasm.
1b. Approach (from AD-416):
An evaluation of cold tolerance responses across four locations within the U.S. grain sorghum belt will be performed in this study. Analysis using Quantitative trait loci (QTL) mapping of the BTx623 x PI567946 RIL population multi-location data will be performed to identify genome regions associated with enhanced early season cold tolerance. Determination of effective means of hybrid development for grain sorghum will be conducted through the analysis of F1 hybrids between three sterile versions of Chinese sources of cold tolerance and three elite US A/B lines. Additional new sets of germplasm from China (Stillwater investigator's accessions), the highlands of Sudan (and Ethiopia), and novel mutant lines of BTx 623 will be characterized for their cold tolerance at early stages and at grain filling stages. Detailed study of cold-tolerant lines will be conducted by characterizing disease reactions of sorghum to various seedling pathogens and through studies of linkage drag with other traits such as the association of cold tolerance with colored testa. At the end of various studies, all data will be assembled and analyzed statistically to (1) identify new germplasm of sorghums (eg; landraces and mutant lines) that can be used sources of cold tolerance for various applications, (2) gather genetic data on inheritance of cold tolerance in hybrids and the relative contribution of maternal effects to serve as guide in variety development; and (3) pinpoint DNA marker and phenotypic information that can applied for development of cold tolerant sorghum germplasm.
3. Progress Report:
For FY 2011-2012, the multilocation trial of the F7 recombinant inbred population BTx623xPI567946 for early season cold tolerance in Texas, Kansas, and South Dakota was completed. The top 20 cold-tolerant lines were selected from this RI population to combine enhanced early season field emergence, robust vigor, with desirable plant height, and non-tannin traits for development of cold-tolerant germplasm for use in breeding programs. A significant increase in germplasm resources, screened for early season cold tolerance under controlled conditions, identification of new non-tannin sources of cold tolerance from Ethiopian highlands, and cold vigor mutants within the BTx623 genetic background (cvg from the AIMs mutant population) were achieved in this reporting period. Genotyping of BTx623 x PI567946 to produce a higher density genetic map was completed for further analysis of QTL markers for early season cold tolerance. Progress in understanding the relationship between early season cold tolerance and tannins through QTL mapping and cloning of tannin genes in sorghum was achieved.