Cold stress and is a major abiotic stress limiting sorghum (Sorghum bicolor L.) growth and productivity in many areas in the world. The development of cold tolerant sorghum lines may allow for expansion of the growing regions and may confer many of the benefits of early season planting. The objective of this study is the identification of the areas of the sorghum genome that influence cold stress. To identify these areas, two stratergies will be employed. First, using two population of 220 RI lines, developed from a cross between CT19 (cold-tolerant) and TX430 (cold-sensitive), QTLs associated with early-season performance under both cold and optimal conditions will be identified by single marker analysis, simple interval mapping (SIM), and composite interval mapping (CIM).  QTLs will be validated using a sweet sorghum population of 210 RIL, derived from a cross between M81-E(cold-susceptible) and ISCV-700(cold-tolerant). Germination was observed under controlled and cold stress conditions. Parental lines and RILs were evaluated under early and normal planting conditions. Traits measured include emergence, emergence index, leaf number, vigor, and dry weight. Next, a differential expression study will be conducted using parental lines and four RILs (2 cold-tolerant, 2 cold-susceptible) identified from field and controlled environments. RNA-Seq will be utilized to determine differential expressed regions of sorghum genome. Results will be presented at meeting.