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:
This cooperative agreement research achieved successful development of 3 strategic recombinant inbred (RI) population resources targeted for early season cold tolerance, assemblage of top performing lines, concurrent with distribution of these new germplasm to sorghum research community. We report the completion of genetic and phenotypic characterization of the 226 RI lines from BTx623xPI567946 (B623*HKZ) for combined strong field emergence and seedling vigor under cool (54-56 F) soil conditions. Multi-location screening for early season cold tolerance for B623*HKZ was conducted in in Texas (2 locations), Kansas, and South Dakota. Quantitative trait loci (QTL) analysis indicated that distinct genes for cold tolerance and vigor can be tapped from B623*HKZ RI progenies. Selection of top performing lines from this RI population and stacking of cold tolerance traits/genes through marker assisted breeding with desirable plant height, and non-tannin phenotypes were initiated. Evaluation of the B623*HKZ RI lines response to seedling pathogen Phytium aphanidermatum indicated a wide range of resistance/susceptibility reactions;,and made possible identification of 12 top cold-tolerant RI lines.