Effect Of Endophyte EF0801 Infection On Endogenous Hormones And Organic Acids In Rice Seedings Under Three Types Of Abiotic Stress

Heavy metal, Na2CO3 and water stress are the three major abiotic factors which seriously affected the yield and quality of rice. In this experiment, rice seedlings were divided into two groups, endophyte-uninfected group(E-) and endophyte-infected group(E+) which was infected with endophytic fungus from Suaeda salsa——EF0801 strains, and two groups were simultaneously treated with different concentrations of Pb(0, 50, 100, 150, 200 μM), Na2CO3(0, 5, 10, 15, 20 m M) and PEG(0, 5%, 10%, 15%, 20%), respectively. The endogenous hormones contents in leaves and the organic acids contents in leaves and roots in E+ and E- seedlings were measured under three stresses in order to investigate the effect of EF0801 strains alleviating the abiotic stress on rice. The research results are as follows:1. Pb stress could inhibit the growth of rice seedlings, decreased the gibberellic acid(GA3) and auxin(IAA) content of leaves, first increased abscisic acid(ABA) and salicylic acid(SA) content and then decreased. EF0801 infection could alleviate the injury of rice seedlings under Pb stress. GA3 and IAA content in E+ were higher than those of E- under 50 μM Pb stress. ABA content in E+ was significantly lower than that of E- under 100~200 μM Pb stress.(GA3 + IAA)/ABA and GA3/ABA in E+ were higher than those in group E-.2. Pb stress enhanced the contents of citrate, acetate and succinate, reduced tartaric acid, and had no effect on oxalate and malate in leaves of rice; Pb stress only increased succinate content and decreased the other organic acid content in roots. The contents of malate and succinate accumulated in leaves of E+ were higher than those of E- under low concentration Pb stress. The contents of tartaric acid under 0, 50 μM Pb stress in roots of E+, succinate under 0-100 μM and oxalate under 50-200 μM were higher than those of E-. Total organic acid content were no difference between E+ and E- in leaves and roots.3. Na2CO3 stress affected the normal growth of rice seedlings. GA3 content decreased gradually, IAA content firstly increased and then decreased, ABA content increased rapidly. GA3 content in E+ was higher than that of E- under 0-10 m M Na2CO3 stress. IAA content in E+ was higher than that of E- under 5-20 m M Na2CO3 stress. IAA/ABA in E+ was always higher than that of E-. EF0801 infection enhanced the resistance of rice by adjusting the balance between endogenous hormones.4. Na2CO3 stress decreased the contents of tartaric acid, oxalate and citrate but increased the content acetate and malate in leaves. Na2CO3 stress decreased the contents of tartaric acid and succinate but increased citrate content in roots. The content of malate under Na2CO3 stress,tartaric acid under 0-5 m M, citrate and succinate under10-20 m M in roots of E+ were higher than those of E-. Total organic acid content in leaves and roots in E+ were higher than those of Eunder 20 m M Na2CO3 stress.5. GA3 and IAA content decreased, while ABA and SA content declined slightly under PEG stress. The contents of GA3, IAA and SA in E+ were significantly higher than those of E-, but ABA content was lower or no difference under PEG stress.(GA3 + IAA)/ABA, GA3/ABA and IAA/ABA in E+ were higher than those in E- under PEG stress.6. The contents of tartaric acid, oxalate, malate and citrate were all decreased in leaves and roots under PEG stress. The contents of oxalate, malate and succinate in leaves were no obvious difference between E+ and E-. The contents of tartaric acid, oxalate, and malate in roots of E+ were significantly higher than those of E- under 20% PEG stress. Total organic acid contents in leaves and roots were no difference between E+ and E-.