Functional genomic and physiological approaches to improving cotton production in water-limiting environments
Adams, Travis C.
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Abstract The identification of genes and regulatory pathways that play a role in abiotic stress tolerance could lead to the development of crops with increased yields and improved quality under water-limiting production schemes. In this study, two cotton (Gossypium hirsutum) genotypes reported to have contrasting yield response under deficit irrigation were chosen to examine transcript and physiological response to water deficit stress. Cotton cultivars Siokra L-23 (tolerant) and CS50 (susceptible) were grown in greenhouse and field trials. Initial transcript profiling studies were carried out on greenhouse-grown plants (8-leaf stage) exposed to a slow-onset water deficit over 6 days followed by a recovery period 1 day after re-irrigation. After irrigation was stopped the plants were monitored daily for photosynthetic response, leaf water potential, and decline of chlorophyll fluorescence to characterize the physiological state of the plants during the stress. Leaf and root tissue was collected at 0 day (well-watered), 3 days after induced stress, 7 days after induced stress, and 1 day after re-watering to monitor recovery. Expression profiling revealed distinct differences between leaf and root tissues and the timeline in which the magnitude of the stress was reflected in those tissues. Although some differences were identified between the two cultivars, the number of genes identified as unique to a particular genotype was relatively small. This research represents one of the initial efforts in examining the transcriptome response to water deficit stress in cotton and will serve as the basis for future studies in identifying the key pathways responsible for controlling this response and potentially, candidate genes for enhancing stress tolerance through transgenic approaches.