Submitted to: Salt and Water Stress in Plants Conference
Publication Type: Abstract Only
Publication Acceptance Date: 9/7/2008
Publication Date: 9/12/2008
Citation: Payton, P.R., Kottapalli, K.R., Rakwal, R., Shibato, J., Burow, G.B., Burke, J.J., Puppala, N., Burow, M. 2008. Transcript and Proteome Response to Water-deficit and Thermal Stress in Peanut[abstract]. Salt and Water Stress in Plants Conference. September 7-12, 2008. Big Sky, Montana. CDROM.
Technical Abstract: Peanut (Arachis hypogaea L.) genotypes from the U.S. mini-core collection were screened for contrasting responses to slow-onset water-deficit and supra-optimal temperature. Seventy accessions were initially screened for basal thermotolerance, photosynthetic response, cellular damage, and recovery from stress. We selected two lines, COC041 (Tolerant) and COC166 (Susceptible), for gene expression and protein profiling studies, as well as detailed physiological characterization and field trials. For transcript profiling, we have developed a high-density oligonucleotide microarray for peanut using approximately 40,000 publicly available peanut oligonucleotide microarray for peanut using approximately 40,000 publicly available peanut ESTs. This chip contains 15,208 probes representing more than 10,000 unique genes in an Agilent Technologies 8 x 15k design (8 arrays per slide). Initial analyses of gene expression changes in leaf tissue revealed significant differences between tolerant and susceptible germplasm. Leaf samples from plants exposed to water deficit were collected at 0.5, 1, 3, 5, and 7 days. The majority of transcript changes were measured in samples exposed to 7 days of water-decifit stress. A total of 623 transcripts showed genotype-specific expression patterns and are currently being analyzed. One- and two-dimensional gel electrophoresis (1- and 2-DGE) was performed on leaf soluble protein extracts from the same plants. A total of 23 and 79 protein bands/spots from 1-D and 2-D gels, respectivley, were analyzed by MALDI-TOF MS and by MS/MS analysis. Forty-nine non-redundant proteins were identified implicating a variety of water-decifit stress response mechanisms in peanut. Lipoxygenase and 1L-myo-inositol-1-phosphate synthase proteins that aid in inter-and intracellular water-deficit stress compared to both susceptible and well-watered control plants. Acetyl-CoA carboxylase, a key enzyme of lipid biosynthesis, increased in relative abundance in the tolerant genotype suggesting the possiblity of a novel fatty acid-mediated mechanism of water-decift stress tolerance. Additionally, there was a marked decrease in the abundance of several key photosynthetic proteins in the tolerant and moderately tolerant genotypes compared to suceptible plants, suggesting a decline in carbon assimilation as a "water economy measure" during stress. Interestingly, the tolerant line exhibited a more rapid decline in photosynthetic rate and conductance but a significantly faster recovery of photosynthetic capacity upon re-watering or return to ambient growth temperature. The results of this detailed study on peanut physiological genomics will be reported at this meeting.