外源NO对NaCl胁迫下M26幼苗养分吸收、蔗糖代谢和氮代谢的影响

Effects of Exogenous NO Application on Nutrient Uptake,Sucrose Metabolism and Nitrogen Netabolism in M26 Seedlings under NaCl Stress

以苹果砧木M26组培苗为试验材料,采用营养液栽培,研究叶片喷施不同浓度NO供体硝普钠(SNP)对NaCl胁迫下幼苗矿质营养元素的吸收以及蔗糖代谢和氮代谢的影响,以期为增强M26幼苗的耐盐性研究提供参考。结果表明:外源NO能够有效缓解NaCl胁迫对M26幼苗养分吸收以及蔗糖代谢和氮代谢的负面影响,总体上以200μmol·L^(-1)SNP的喷施效果最佳。外源NO处理不仅能够有效提升NaCl胁迫下幼苗对氮、磷和钾的吸收,而且提高了幼苗的蔗糖代谢水平,表现为进一步提高SPS和SS的活性以及 MdSPS6和 MdSuSy2的表达水平,并且AI和NI的活性也得到提高,同时也有效改善了幼苗的氮代谢能力,表现为提高了NR、GS和GDH的活性与硝态氮的含量,降低了铵态氮的含量,使铵毒害降低,并且也上调了MdNR和MdNIR的表达。可见,外源NO可在一定程度上缓解NaCl胁迫对M26幼苗造成的伤害,从而提高幼苗的耐盐性,促进幼苗生长。

In this study,M26 tissue culture seedlings of apple rootstock were used as experimental materials,we used nutrient solution cultivation to investigate the effects of leaf spraying with different concentrations of NO donor sodium nitroprusside(SNP)on the uptake of mineral nutrients,sucrose metabolism,and nitrogen metabolism of seedlings under NaCl stress.The findings provide a foundational resource for enhancing the salt tolerance of M26 seedlings.The results showed that exogenous NO effectively alleviated the effects of NaCl stress on nutrient uptake,sucrose and nitrogen metabolism in M26 seedlings,with the best overall effect of 200μmol·L^(-1)SNP spraying.Exogenous NO not only effectively enhanced the uptake of N,P and K by seedlings,but also increased the level of sucrose metabolism in seedlings.This enhancement was confirmed by increased activities of SPS and SS,as well as heightened expression levels of MdSPS6 and MdSuSy,the activities of AI and NI also was also increased.It improved the nitrogen metabolism of seedlings,increasing NR,GS,and GDH activity,and nitrate nitrogen content while reducing ammonium nitrogen content.thus mitigating ammonium toxicity.It also upregulated the expression of MdNR and MdNIR.In conclusion,the exogenous NO can alleviate the damage caused by NaCl stress to M26 seedlings to a certain extent,thereby improving the salt tolerance of seedlings and promoting seedling growth.