Physiological And Proteomic Of Banana Under Drought Stress

Banana is a large herbaceous plant grown in tropical and subtropical areas, it is not only one of the main fruits in the world but also one of China’s four big fruit, which has been recognized as the world’s fourth largest food crops by the United Nations food and agriculture organization (FAO). Drought is a long-standing worldwide problem and it has become one of the main obstacle restricting the development of the agricultural production in the world, so China also faces many problems of water shortage. To carry out the research about physiology and biochemistry analysis and related proteins expression of banana under drought stress would have important significance to learn and clarify the drought resistance mechanism of banana, and it would be useful to drought-resistant breeding. This study chose guangxi Guijiao 1 as experimental material, and selected the red soil for pot experiment, to research the changes of drought stress phenotype and varieties of physiological metabolism in banana seedling leaves under different drought stress intensity. We would study differentially expressed proteins in banana seedling leaves under different drought stress intensity by using iTRAQ technology. The main research results are as follows:First, With the increase of the intensity of water stress, the leaf wilting degree of banana seedling leaves increased, the leaf curl degree deepens gradually and the main lateral veins prominent phenomenon was gradually increasing, with a large number of purple. Net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr) was lowering on the overall trend with the increase of drought degree, but the change trend of intercellular CO2 concentration (Ci) was the opposite change tendency. We found that the net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr) were positively correlated to each other through counting the correlation of four photosynthetic indexes determination. Along with the strengthening of drought stress, the leaf chlorophyll content, soluble protein content, malondialdehyde content were showing a "go up-go down-go up" trend, proline content showed the tendency of increase after the first drop. The change of the form, the strength of the photosynthesis and the change of osmotic regulation substances were the key indicators of banana drought resistance.Second, the results of proteomics by iTRAQ showed that 5337 peptide fragments and 1655 proteins that matched banana protein library were separated, and 78 differentially expressed proteins identificated, which included 32 up regulated proteins and 46 down regulated proteins. there were 423 differentially expressed proteins which had more than 20% of the peptides coverage, and this differentially expressed proteins ratio in total protein 25.59%. There were 4982 peptide fragments which had about 6-19 amino acid residues, and these peptide fragments ratio in total peptide fragments 93.35%. The up-regulated proteins and down-regulated proteins had been classified to biological process, cellular component and molecular function through GO secondary function classification statistics, we found that the differentially expressed proteins mainly participated in cellular process, metabolic process, single-organism process and response to stimulus in biological process; primarily targeted cell, organelle and membrane in cellular component; mainly included catalytic activity and binding in molecular function. The subcellular location of differentially expressed proteins made us find out that up-regulated proteins and down-regulated proteins were mainly located in chloroplast(59%) and cytosol (16%). The significant enrichment of KEGG pathway analysis among differentially expressed proteins showed that the differentially expressed proteins mainly participated in energy metabolism, carbohydrate metabolism, amino acid metabolism and Metabolism of terpenoids and polyketides. The energy metabolism and carbohydrate metabolism, amino acid metabolism were particularly important among them. In addition, we had conducted a more comprehensive description and research about the individual proteins in order to find some differentially expressed proteins which had high research value and provide the basis of the molecular level for further reveal drought-resistant mechanism of banana.