Decreased CO2 availability and inactivation of Rubisco limit photosynthesis in cotton plants under heat and drought stress in the field |
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| Institution: | 1. US Department of Agriculture, Agricultural Research Service, Arid-Land Agricultural Research Center, 21881 N. Cardon Lane, Maricopa, AZ 85138, USA;2. Department of Agricultural and Biosystems Engineering, University of Arizona, Maricopa Agricultural Center, 37860 W. Smith-Enke Road, Maricopa, AZ 85138, USA;1. Key Laboratory of Crop Growth Regulation, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, PR China;2. Department of Crop and Soil Sciences, University of Georgia, Tifton 31794, USA;1. Global Change Research Institute CAS, Bělidla 986/4a, 603 00 Brno, Czech Republic;2. Mendel University in Brno, Faculty of Agronomy, Zemědělská 1, 613 00 Brno, Czech Republic;3. Mendel University in Brno, Faculty of Forestry and Wood Technology, Zemědělská 3, 613 00 Brno, Czech Republic;4. Central Institute for Supervising and Testing in Agriculture, Hroznová 65/2, 656 06 Brno, Czech Republic;1. Department of Crop and Soil Sciences, University of Georgia, 115 Coastal Way, Tifton, GA, 31794, United States of America;2. USDA, Agricultural Research Service, National Peanut Research Laboratory, 1011 Forrester Drive, Dawson, GA, 39842, United States of America;3. Delta Research and Extension Center, Mississippi State University, PO Box 197, Stoneville, MS, 38776, United States of America;4. Fisher Delta Center, University of Missouri, 147 State Highway T, Portageville, MO 63873, United States of America;5. Department of Plant Agriculture, University of Guelph, 50 Stone Road E., Guelph, Ontario, N1G 2W1, Canada |
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| Abstract: | Heat and drought stresses are often coincident and constitute major factors limiting global crop yields. A better understanding of plant responses to the combination of these stresses under production environments will facilitate efforts to improve yield and water use efficiencies in a climatically changing world. To evaluate photosynthetic performance under dry-hot conditions, four cotton (Gossypium barbadense L.) cultivars, Monseratt Sea Island (MS), Pima 32 (P32), Pima S-6 (S6) and Pima S-7 (S7), were studied under well-watered (WW) and water-limited (WL) conditions at a field site in central Arizona. Differences in canopy temperature and leaf relative water content under WL conditions indicated that, of the four cultivars, MS was the most drought-sensitive and S6 the most drought-tolerant. Net CO2 assimilation rates (A) and stomatal conductances (gs) decreased and leaf temperatures increased in WL compared to WW plants of all cultivars, but MS exhibited the greatest changes. The response of A to the intercellular CO2 concentration (A–Ci) showed that, along with stomatal closure, non-stomatal factors associated with heat stress also limited A under WL conditions, especially in MS. The activation state of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) decreased in WL compared to WW plants, consistent with thermal inhibition of Rubisco activase activity. The extent of Rubisco deactivation could account for the metabolic limitation to photosynthesis in MS. Taken together, these data reveal the complex relationship between water availability and heat stress for field-grown cotton plants in a semi-arid environment. Both diffusive (drought-stress-induced) and biochemical (heat-stress-induced) limitations contributed to decreased photosynthetic performance under dry-hot conditions. |
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