干旱对不同水稻萌发种子中逆境生理及相应基因表达的影响

Effect of Drought Stress on Physiology and Corresponding Gene Expression in the Germination Seeds of Different Rice Germplasm

为揭示萌发期不同水稻的抗旱性机理,以水稻旱敏感材料(Calrose、京宁10号、山形86)和抗旱性材料(Farry、松粳3号、宁粳36)为研究对象,开展了模拟干旱胁迫(15%PEG-6000)对不同水稻萌发种子生长指标、生理指标及相应基因表达量的影响研究。结果表明:正常条件下,旱敏感和抗旱性材料萌发种子各生长指标、抗逆相关基因表达量之间无显著差异;但生理指标有明显变化,表现为不同材料间超氧化物歧化酶(SOD)、过氧化物酶(POD)活性、可溶性糖(SS)和过氧化氢(H 2O 2)含量无显著差异,旱敏感性材料山形86的丙二醛(MDA)、超氧阴离子(O 2-·)含量显著高于其他材料;抗旱性材料宁粳36的过氧化氢酶(CAT)活性、脯氨酸(Pro)、可溶性蛋白(SP)含量显著高于其他材料。干旱胁迫下,相比于旱敏感性材料,抗旱性材料萌发种子的相对发芽势(RGP)、相对芽长(RSL)、萌发期抗旱指数(GDRI)和活力指数(VI)分别增加了0.03~0.07百分点,0.32~0.39百分点,0.12~0.18百分点和92.41%~108.39%;抗旱性材料萌发种子中MDA和活性氧(O_(2)^(-)·、H_(2)O_(2))含量分别降低了2.54%~61.64%,19.60%~46.30%和35.61%~62.02%;渗透调节物质(Pro、SS、SP)含量分别增加了5.93%~18.29%,1.08%~7.97%和3.47%~6.03%;抗氧化酶(SOD、POD、CAT)活性分别提高17.29%~33.12%,15.24%~76.06%和14.68%~18.61%;脯氨酸合成关键基因OsP5CS、抗氧化酶合成基因(OsALM1、OsPOX1、OsCATC)的相对表达量分别上调了2.66%~182.31%,57.14%~513.27%,0.38%~109.06%和63.39%~184.25%。综合分析表明,干旱胁迫抑制了水稻种子的萌发,影响了萌发期种子中的生理特性及其相应基因的表达。干旱胁迫下,无论是抗旱性材料还是旱敏感性材料,活力指数(VI)、过氧化物酶(POD)以及过氧化物酶合成基因(OsPOX1)是影响水稻种子萌发的关键指标。除以上指标外,可溶性蛋白(SP)、脯氨酸合成基因(OsP5CS)、过氧化氢酶基因(OsCATC)是影响抗旱性材料的其他关键指标,相对芽长(RSL)、过氧化氢(H 2O 2)、超氧化物歧化酶基因(OsALM1)是影响旱敏感性材料的其他关键指标。

To reveal the mechanism of drought resistance of different resistant rice during germination period,Rice drought-sensitive materials(Calrose,Jingning 10,Shanxing 86)and drought resistance materials(Farry,Songjing 3,Ningjing 36)were studied on the effects of simulated drought stress(15%PEG-6000)on the growth index,physiological indexes and corresponding gene expression of different rice seeds.The results showed that under normal conditions,there were no significant differences in the expression levels of growth indicators and stress-related genes between drought-sensitive and drought-resistant cultivars.However,changes in physiological indicators were shown that there were no significant differences in the activities of superoxide dismutase(SOD)and peroxidase(POD),the contents of soluble sugar(SS)and hydrogen peroxide(H 2O 2)among different genotypes.The contents of malondialdehyde(MDA)and superoxide anion(O 2-·)in the drought-sensitive cultivar Shanxing 86 were significantly higher than those in other materials,and the contents of catalase(CAT),proline(Pro)and soluble protein(SP)of drought resistant Ningjing 36 were significantly higher than those of other materials as well.Under drought stress,the relative germination potential(RGP),relative bud length(RSL),germination drought resistance index(GDRI)and vitality index(VI)of germinating seeds increased by 0.03-0.07 percentage,0.32-0.39 percentage,0.12-0.18 percentage and 92.41%-108.39%,respectively;MDA and reactive oxygen species(O_(2)^(-)·、H_(2)O_(2))contents in germinating seeds of drought-resistant cultivars decreased by 2.54%-61.64%,19.60%-46.30%and 35.61%-62.02%respectively compared with drought-sensitive cultivars.The contents of osmotic regulating substances(Pro,SS,SP)increased by 5.93%-18.29%,1.08%-7.97%and 3.47%-6.03%respectively.The activities of antioxidant enzymes(SOD,POD,CAT)were increased by 17.29%-33.12%,15.24%-76.06%and 14.68%-18.61%respectively.The relative expression levels of OsP5CS,antioxidant enzyme synthesis genes(OsALM1,OsPOX1,OsCATC)were up-regulated by 2.66%-182.31%and 57.14%-513.27%,0.38%-109.06%and 63.39%-184.25%respectively.Comprehensive analysis showed that drought stress inhibited the germination of rice seeds and affected the physiological characteristics of seeds and the expression of corresponding genes during germination.Under drought stress,vigor index(VI),peroxidase(POD)and peroxidase synthesis gene(OsPOX1)are the key indicators affecting rice seed germination,whether it is drought-resistant or drought-sensitive materials.In addition to the above indicators,soluble protein(SP),proline synthesis gene(OsP5CS)and catalase gene(OsCATC)are other key indicators affecting drought-resistant materials.Relative shoot length(RSL),hydrogen peroxide(H 2O 2)and superoxide dismutase gene(OsALM1)are other key indicators affecting drought-sensitive materials.