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Study Of Drought-Responsive Proteins And Metabolites In Bermudagrass

Posted on:2012-06-25Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y ZhaoFull Text:PDF
GTID:1110330362958339Subject:Botany
Abstract/Summary:PDF Full Text Request
Drought is one of the major abiotic factors limiting plant growth, which induces various changes at different cellular levels. Although morphological and physiological mechanisms of drought tolerance have been examined extensively in bermudagrass, limited information is available on the drought-responsive proteins or metabolites. By technologies of proteomics, western blotting and metabolomics, three experiments were carried out with different bermudagrass genotypes. The first was study of drought-responsive proteins in bermudagrass leaves. The second was responses of protein expression to drought stress in bermudagrass leaves. The third was study of drought-responsive metabolites in leaf and root of bermudagrass. The main contents and results were as follows:1. Plants of bermudagrass'Tifway'and'C299'were exposed to drought stress for 15 d by withholding irrigation in a growth chamber. Leaf electrolyte leakage increased and photochemical efficiency and relative water content declined under drought stress, but the extent of changes in each of the physiological parameters for'Tifway'was less pronounced than those for'C299'. Total proteins of leaves were extracted from well-watered and drought-stressed plants at 10 d of treatment, and separated by two-dimensional gel electrophoresis. According to the quantitative analysis of protein gels, a total of 54 protein spots in the two genotypes showed reproducible and significant changes in the abundance, with 32 increasing and 22 decreasing. All drought-responsive proteins were subjected to mass spectrometry analysis, which were mainly involved in metabolism, energy, cell growth/division, protein synthesis, and stress defense. Functional analysis of differential drought-responsive proteins between the two genotypes suggested that the superior drought tolerance in'Tifway'could be mainly associated with less severe decline in the abundance level of proteins involved in photosynthesis (Chl a-b, ATPSα, PRK and Rubisco) and greater increase in the abundance level of antioxidant defense proteins (SOD, APX, DHAR, MDHAR and Prx).2. Plants of bermudagrass'Midrion','Tifgreen','Tifway','Champion','Pariot'and'Celebration'were exposed to drought stress for 15 d by withholding irrigation in a growth chamber. Evaluation of drought tolerance in different genotypes of bermudagrass was based on turf quality, leaf relative water content, photochemical efficiency, net photosynthetic rate and electrolyte leakage. Expression of Rubisco LSU, SOD, DHAR and MDHAR under well-watered and drought-stressed conditions was detected by western blotting analysis. Drought-tolerant'Midrion'and'Tifway'had lower degradation of Rubisco LSU and greater increase of SOD, DHAR and MDHAR compared to drought-sensitive'Pariot'and'Celebration'.3. Physiological responses to drought stress were evaluated by measuring leaf relative water content, chlorophyll content, photochemical efficiency and cell membrane leakage, and all parameters indicated that'Tifway'exhibited better drought tolerance than'C299'. Methanol was used for metabolites extraction from well-watered and drought-stressed plants at 5, 10 and 15 d of treatment. The gas chromatography-mass spectrometry analysis identified 44 drought-responsive metabolites in leaves or roots of two genotypes, including 15 organic acids, 14 amino acids, 10 sugar and sugar alcohols, 3 fatty acids and 2 N-compounds. The differential metabolic expression pattern between two genotypes differing in drought tolerance demonstrated that the superior drought tolerance in'Tifway'could be related to the accumulation or maintenance of a series of metabolites, including 3 organic acids (ferulate, glycerate and itaconate), 3 amino acids (alanine, proline and valine), 5 sugar and sugar alcohols (galactose, sucrose, melibiose, gluticol and mannitol), 2 unsaturated fatty acids (α-linolenate and linoleate), and 2 N-compounds (ethanolamine and putrescine).
Keywords/Search Tags:Drought stress, bermudagrass (Cynodon dactylon), drought-responsive proteins, drought-responsive metabolites
PDF Full Text Request
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