Physiological And Biochemical Mechanism Of Drought Stress Of Barley During Seed Germination Period And Screening Differentially Expressed Genes

The insufficient of soil moisture content during barley germination stage in rainedfarming region in the northwest of China is a negative factor for high yield. The effect ofdrought stress simulated by polyethylene glycol on barley seed germination was studied onmorphological, physiological, biochemical and molecular basis to further clarify themechanism of drought resistance, to establish method system for drought resistanceevaluation and to indentify drought resistance germplasm during seed germination stage.1. Barley seed germination test under drought stress simulated by polyethylene glycolwas done to determine morphological parameters. The results showed that seed germinationwas completely restrained by25%polyethylene glycol and the suitable concentration ofpolyethylene glycol for drought resistance evaluation of barley could be20%PEG8000.2. Barley seed germination test under drought stress simulated by polyethylene glycolwas done to determine physiological and biochemical parameters. The results showed thatwith the increase of polyethylene glycol concentration, the malondialdehyde contents oftested cultivars were on the rise, the activities of superoxide dismutase and peroxidaseenhanced and the osmotic regulation substances, such as soluble sugar, soluble protein andproline, accumulated in large quantities.3. The correlation analysis showed that the9morphological parameters weresignificantly correlated with barley drought resistance. The9morphological parameters canbe divided into five main factors by factor analysis and the variance contribution rate to eachparameter was higher than85%, preliminary speculating that the9morphological parameterscould be used as the identification parameter for barley drought resistance. Because the factor1contains51.73%information amounts, the length of germ, the dry weight of radicle, the dryweight of plumule, and material transfer rate can be used as the major identification parameterfor barley drought resistance during seed germination stage and others can be used assecondary identification parameter.9drought resistance cultivars （Z027S078T, Xinyin D₉,Xinyin D₇, Xinpi1, P09-9, Xinpi2, Jipi2, Z182U038V and Poland） were screened out by themethod of membership function and clustering analysis and Z027S078T and Xin yin D₇werethe high drought resistance cultivars; the sensitive cultivar was Kenpi6.4. Barley seed germination test under drought stress simulated by20%polyethyleneglycol8000was done to extract mRNA and differentially expressed genes were screened bymRNA differences display technology. Based on the sequence results of10differentiallyexpressed bands to predict protein, predicted protein were signal peptidase, AAA-typeATPase family protein, presenilin family protein, protein binding protein, phospholipase C,cyclin family protein, protein kinas, ankyrin repeat-containing protei, putative eukaryotic translation initiation factor4gamma and photosystem II cp47protein。...