N-乙酰氨基葡萄糖对水稻的抗寒作用研究

Effects of N-acetyl-D-glucosamine on improving cold stress tolerence of rice

  • 摘要: 【目的】探究N-乙酰氨基葡萄糖(N-acetyl-D-glucosamine,NAG)对水稻幼苗的抗寒效果及其潜在的抗寒机制,以期为NAG在农业免疫诱抗领域的应用提供理论依据。【方法】以水稻品种内5优907为供试材料,外源施用不同浓度(0、50、100、150 mg/L)的NAG进行根系培养,测定低温条件下水稻幼苗的生长指标、叶绿素含量及可溶性糖含量,表征NAG的抗寒效果并筛选最适施用浓度。进一步在生理生化水平从渗透调节系统、根系系统、抗氧化系统和脱落酸代谢途径探究NAG对水稻幼苗的抗寒机制。【结果】外源施用NAG可促进水稻幼苗在低温环境下正常生长,具有明显的抗寒效果,其最适施用浓度为100 mg/L,在此浓度下幼苗单株鲜重(0.118±0.009 g)、株高(21.21±0.72 cm)、根长(5.76±0.43 cm)及可溶性糖(41.031±0.992μg/g)和总叶绿素含量(5.959±0.020 mg/g)较对照组涨幅最大,分别显著增长14.14%、7.14%、7.22%、63.09%和36.79%(P<0.05,下同)。生理生化水平相关结果表明,100 mg/L NAG促进寒害幼苗中渗透调节物质积累,可溶性蛋白、脯氨酸和游离氨基酸积累量较低温对照组分别显著增长19.58%、19.49%和36.82%;保护幼苗根系系统,促进寒害幼苗根系活力提高至低温对照组的1.56倍,并使茎叶组织中硝态氮含量下降15.65%;有效促进幼苗中丙二醛积累量下降23.92%,并将超氧化物歧化酶(SOD)、过氧化物酶(POD)活力分别提高34.94%和25.42%,保护幼苗抗氧化系统;增加寒害幼苗脱落酸代谢通路中OsNCED、OsSDRAAO基因表达量至低温对照组的3.52、1.73和1.64倍,从而实现幼苗中内源脱落酸的积累。【结论】外源施用NAG根系处理能够调控低温胁迫下水稻幼苗渗透调节系统、根系系统、抗氧化系统及内源脱落酸代谢途径,进而提高水稻抗寒性。

     

    Abstract: 【Objective】To evaluate the cold resistance effect of N-acetyl-D-glucosamineon on rice seedlings, and to further explore its potential cold resistance mechanism, with a view to providing the theoretical basis for the application of NAG in the field of agricultural immune induction.【Method】With the rice variety Nei 5 You 907 as the test material, different concentrations(0, 50, 100, 150 mg/L) NAG were exogenously applied to rice seedlings for root culture. The growth potential, growth index, chlorophyll content and soluble sugar content of rice seedlings under low temperature conditions were measured to characterize the cold resistance effect of NAG and to screen the optimum applied concentration. Furthermore, the cold resistance mechanism of NAG on rice seedlings was explored from osmotic adjustment system, root system, antioxidant system and abscisic acid metabolism pathways at the physiological and biochemical level.【Result】Exogenous application of NAG promoted the growth of rice seedlings in low temperature environments, and had obvious cold resistance effect. The optimum applied concentration was 100 mg/L. Under this concentration, the fresh weight(0.118±0.009 g), plant height(21.21±0.72 cm), root length(5.76±0.43 cm), soluble sugar(41.031±0.992 μg/g) and the total chlorophyll content(5.959±0.020 mg/g) of seedlings increased the most in comparison with the control group, which significantly increased by 14.14%, 7.14%, 7.22%, 63.09% and 36.79% respectively(P<0.05, the same below). The results of the physiological and biochemical level showed that 100 mg/L NAG promoted the accumulation of osmotic adjustment substances, soluble protein, proline, free amino acid in the cold injury seedlings increased significantly by 19.58%, 19.49%and 36.82% respectively compared with the control group;effectively protected the root system of seedlings, the root activity of cold injury seedlings was increased to 1.56 times, and the nitrate nitrogen content in the stem and leaf tissues was decreased by 15.65% compared with the low-temperature control group;effectively reduced the accumulation of malondialdehyde in the cold injury seedlings by 23.92% and increased the activities of superoxide dismutase(SOD) and peroxidase(POD) by 34.94% and 25.42% respectively, thereby protecting the antioxidant system of seedlings;increased the OsNCED, OsSDR and AAO genes expression in the abscisic acid metabolism pathway to 3.52, 1.73 and 1.64 times of low temperature control, so as to achieve the accumulation of endogenous abscisic acid in cold injury seedlings.【Conclusion】Exogenous application of NAG with root treatment can regulate osmotic adjustment system, root system, antioxidant system and the endogenous abscisic acid metabolism pathway of rice seedlings under cold stress, thereby improving the cold resistance of rice.

     

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