Submitted to: Keystone Symposia
Publication Type: Abstract Only
Publication Acceptance Date: 1/12/2006
Publication Date: 4/8/2006
Citation: Burow, G.B., Mccartor, K.D., Zhang, D., Nguyen, H., Burke, J.J., Payton, P.R. 2006. Characterization of sorghum water stressed leaf transcriptome and stay green expression via est analysis [abstract]. Keystone Symposia. p 46.
Technical Abstract: Sorghum (Sorghum bicolor L. Moench), is considered as one of the most tolerant grass species to abiotic stresses including water/drought and heat stress. An expression of tolerance to water stress in sorghum after flowering is the stay-green trait, which refers to the maintenance of green leaves and stems at post anthesis under drought conditions. To elucidate the molecular mechanisms underlying the response to water stress and the stay green phenotype expression, 10,300 expressed sequence tags (ESTs) corresponding to 4720 contigs +singletons, were analyzed from subtracted leaf cDNA libraries of cultivars, TX7000 (a pre-flowering drought tolerant line source of DSBF library) and BTx 642(formerly known as B35, a post flowering drought tolerant line source of DSAF library). Approximately 14% of contigs were present in both libraries, while 28.5% and 58.5% were found unique to DSBF and DSAF libraries respectively. These ESTs represent 2,582 genes with known or predicted function. Majority of ESTS (24.3%) correspond to genes whose products are involve in metabolism, while 25 % of sequences are genes involve in stress response and regulatory functions. Included in the stress response category are genes for dehydrin, heat shock proteins, cysteine protease, betaine aldehyde dehydrogenase and delta-1-pyrroline 5-carboxylate synthetase among others. These EST sequences represent a subset of water stress upregulated genes that can serve as a unique genomic resource for a comprehensive study of water/drought stress in sorghum. As a genomic application, in-silico mapping of contigs revealed that 8.2% of the ESTs correspond to markers in the sorghum genetic map which were distributed in all 10 sorghum chromosomes. The functional study of ESTs reported here provide further evidence for the polygenic and complex nature of stay green and that this delayed senescence response to water stress involves integration of various metabolic pathways that are closely regulated along with stress related responses.