AN EST ANALYSIS OF GENES EXPRESSED DURING DROUGHT STRESS IN COTTON

Authors: MCCARTOR, KAYLA - TTU; NGUYEN, HENRY - UNIVERSITY OF MO; PRATT, LEE - UNIVERSITY OF GA; Payton, Paxton

Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/11/2003
Publication Date: 1/15/2003
Citation: Mccartor, K., Nguyen, H., Pratt, L., Payton, P.R. 2003. An est analysis of genes expressed during drought stress in cotton[abstract]. Plant and Animal Genome Conference. p. 286.

Interpretive Summary:

Technical Abstract: Drought stress is one of the major abiotic factors limiting fiber yield and lint quality in cotton. The economic importance of cultivated cotton has stimulated extensive studies of fiber development. Manipulation during domestication has resulted in modern cotton varieties in which the fiber is longer, and stronger than that of most wild ancestors. Fiber properties, particularly strength, length, and fineness, require further improvement to meet economic pressures and to facilitate more efficient spinning technology. Improvement of cotton fibers using molecular techniques is feasible (John and Stewart, 1992; John and Keller, 1996). Additionally, because theses parameters are under genetic control (Basra and Malik, 1984), an understanding of the regulatory elements and genes expressed during fiber development is required before any genetic manipulation can be used to enhance quality under optimum and stress conditions. As drought has the greatest effect during boll formation, it is important to understand the changes that occur during this critical stage of development. Four cDNA libraries were constructed at two different stages of boll formation, 8-10 days post-anthesis (dpa) and 15-20 dpa from drought-stressed and irrigated control bolls with vector HybriZap kit. These stages encompass fiber elongation and fiber maturation, respectively. The synthesis of fiber components during these critical stages plays a significant role in fiber length, fineness, and strength. The 5' ends of 1032, 287, 1430 and 840 randomly selected clones from 8dpa stressed, 8dpa irrigated, 15dpa stressed, and 15dpa irrigated boll libraries were sequenced and annotated in order to identify potentially informative genes. The blastx algorithm was used to translate each EST nucleotide sequence into six possible reading frames and compared with protein sequence database available through National Center for Biotechnology Information (NCBI). Sequence homology search indicated that 496 (48.1%) from 8-10 drought stresses EST's and 139 (48.6%) from control library exhibited significant similarities to characterized database entries. There were 148 and 52 unique or novel sequences from stress and normal library respectively that had no match at all to any sequences in the database. From 1032 sequences from 8-10 dpa stressed boll library 974 were unigenes. These ESTs were divided into 12 categories depending upon gene functions. The fact that cotton is able to acclimate to a remarkable degree to water deficit makes it an excellent model for studying these responses in a crop plant. Improved drought tolerance of crop plants is vital to the sustainability of agriculture in Texas and the Southwest. The objectives of this research are to take an integrative approach to study the effects of drought stress on cotton fiber development. We propose to combine physiological, biochemical, and gene expression data to identify targets for the genetic manipulation of drought responses and fiber development. The ultimate goal of this research is to identify those genes in cotton that are critical for stress acclimation in cotton that be used to enhance drought tolerance and fiber quality. We present, here, our analysis of this collection of ESTs and future planned experiments to further characterize this collection.