2010 Annual Report 1a.Objectives (from AD-416) Improve crop tolerance to heat stress by devising appoaches to impove the ability of Rubisco activase to activate Rubisco at leaf temperatures above the optimum for photosynthesis. Develop new approaches to improve chilling tolerance by identifying metabolic mechanisms that limit biochemical/physiological processes most sensitive to chilling temperatures. Develop improved germplasm resources for abiotic stress resistance and fiber quality in G. hirsutum utilizing and integrating classical and biotechnology-based methodologies. Develop improved germplasm resources for abiotic stress resistance and fiber quality in G. barbadense utilizing and integrating classical and biotechnology-based methodologies. 1b.Approach (from AD-416) The genetic potential of cotton, and crop species in general, for producing of abundant high quality economic yield as is severely compromised by specific abiotic stresses, like temperature and water, that are endemic to the arid-southwestern U.S. In addition, early season chilling stress impacts yield by stunting growth and delaying planting date. The negative impact of these stresses is likely to intensify as the global climate changes and water availability becomes more limiting. The mission of this research unit is to use a multidisciplinary apporach to improve stress tolerance and yield in cotton. Fundamental approaches that integrate physiology, biochemistry, biotechnology and classical plant breeding will be used to identify and modify the response of cotton to environmental stress. Through this research, new sources of cotton germplasm will be developed with improved stress tolerance, as well as higher fiber quality and enhanced yield. The basic biochemical strategies developed for improving stress tolerance in cotton will have broad application to the variety of crop plants cultivated in arid environments. Replaces 5344-21000-008-00D (3/06) and 5347-21000-009-00D (3/10). 3.Progress Report Due to completion of the old project plan (5347-21000-009-00D), and the need to synchronize the review cycles for projects within NP301 and 302 (due to merger of these National Programs), a 3-year bridging project (5347-21000-011-00D) has been established to build upon and extend research conducted in the old project plan. The general area of research will focus on improving crop tolerance to abiotic stress factors common to arid southwestern U.S. cropping systems.