| Cotton drought resistance controlled by multiple genes, there response different degree to drought sensitive among different genotype cotton varieties. Ascorbic acid peroxidase(APX) is an enzyme and play an important role in the process of remove oxygen free radicals(ROS) in plant. Previous studies indicate that cytoplasm APX(cAPX) could resistant to extreme conditions most in APX gene family, is the key enzymes of plant stress survival. There are a lot of report about cytoplasm APX1 genes resistance extremely environment in rice, jujube, pea, cotton and so on, but the cytoplasm APX2 are rarely studied.24 upland cotton varieties as materials in this study. Drought stress was set in cotton florescence, evaluate materials drought resistance level by D value combined with cluster analysis, plant morphological identification method in different traits, closely associated with drought resistance under various characters to find out the optimal individual indicators, then screening of drought resistance as experimental material to clone GhAPX2 gene,construct its plant expression vector and analysis its expression pattern in seedling stage and blooming period for different t genotype varieties. The main results were as follows:1. Flowering and boll-setting stage as main study period. Single indicator in different traits response different degree to drought sensitive. That closely associated with drought resistance indices are net photosynthetic rate(Pn), water use efficiency(WUE) and ascorbic acid peroxidase(APX) of the photosynthetic physiological and biochemical index. That closely associated with drought resistance indices are fiber length, the breaking strength, Micronaire and textile consistency of fiber quality indicator.That closely associated with drought resistance indices of plant are height, effective branch numbers, the number of effective fluid and the yield of the index of agronomic traits. There are some differences based on different indicators as the research object of the D value clustering results, Based on the photosynthetic physiological and biochemical index D value in the physiological indexes of drought resistance type materials mainly include ZhongR 2007, Beiersinuo,Xinluzao11 and CQJ-5; Based on fiber quality index D value of fiber quality drought-resistant type materials mainly include ND359-5, 10615-3 and Xinluzhong36;Based on agronomic traits production index of drought resistance index D value type material with Xinluzao11, Beiersinuo,Xinluzhong36, Y1169 and Xinluzao50.2. GhAPX2 cloning and bioinformatics analysis showed that its ORF box for 753 bp, Encoding 250 amino acid residues, coding hydrophilic protein, have no signal peptide. Transmembrane protein analysis results showed that the protein for membrane proteins, containing typical conservative areas of POD enzyme and belong to the peroxidase family members, have heme binding sites, K+ binding sites, the substrate binding site and other typical feature of APX gene family. Phylogenetic tree result shows that the gene encoding protein is relative closest with Asiatic cotton cAPX2.With cloned plasmid as template at the same time, then design primers contain Bgl ? and Spe ? enzyme sites, successful construction of plant expression vector pCAMBIA1304-Gh APX2, Laid the foundation for subsequent genetically modified tests.3. The results of RT-PCR in seeding stage with the good drought resistance and fiber qualities variety Xinluzhong36 and the extremely opposite variety Xinluzao26 as the test materials show that GhAPX2 expressed in different organizations in cotton, it has the highest express in leaf blade at 3 leaves and 5leaves period, but when the seeding turn into 7 leaves, the highest express occurred in stem organization.Drought stress with 11 % PEG-6000 deal with 48 h could enhance the expression level of the gene; When the bolls in 0 DPA, 5 DPA and 10 DPA stage, the gene expression levels continue to rise in stress group and control group, and the stress in the group to express quantity is greater than the control group. Geneexpression in Xinluzao26 obviously higher than Xinluzhong36, but on the contrary in leaf. So presumably the genes in the blade of a large number of expression is helpful to improve the level of cotton and drought,and opposite in the fiber. |
PDF Full Text Request