硅促进盐胁迫下黄瓜NHX1基因表达及Na^+在液泡中的区隔化效应  

Silicon upregulates NHX1 expression to enhance Na^+ partitioning into vacuoles in leaf mesophyll cells of cucumber under salt stress

作　　者：缑天韵 苏艳 陈馨航 朱永兴 宫海军[1] GOU Tian-yun;SU Yan;CHEN Xin-hang;ZHU Yong-xing;GONG Hai-jun(Shaanxi Engineering Research Center for Vegetables/College of Horticulture,Northwest A&F University,Yangling,Shaanxi 712100,China;College of Horticulture and Gardening,Yangtze University,Jingzhou,Hubei 434025,China)

机构地区：[1]陕西省蔬菜工程技术研究中心/西北农林科技大学园艺学院,陕西杨凌712100 [2]长江大学园艺园林学院,湖北荆州434025

出　　处：《植物营养与肥料学报》2020年第11期1923-1934,共12页Journal of Plant Nutrition and Fertilizers

基　　金：国家自然科学基金项目(31772290);陕西省重点研发计划特色产业创新链项目(2019TSLNY01-02)。

摘　　要：【目的】硅可提高植物的耐盐性,但不同植物中硅提高耐盐性的机理并不相同。探究硅对盐胁迫下黄瓜幼苗的氧化损伤、Na^+积累和激素水平的影响,以阐明硅提高黄瓜耐盐性的机制。【方法】以基因型为Mch-4的黄瓜幼苗为试材,进行水培试验。营养液中NaCl的胁迫浓度为65 mmol/L,施硅水平为Na2SiO3·9H2O0.3 mmol/L。在处理10天后,测定黄瓜幼苗生物量、Na^+含量与分配、Na^+转运相关基因表达水平及激素含量。【结果】施硅可改善盐胁迫下黄瓜幼苗的生长,减轻植株的氧化损伤。硅对盐胁迫下黄瓜根系和叶片Na^+含量无明显影响,可显著降低根和叶中质膜Na^+/H^+反向转运蛋白基因SOS1的表达量,对高亲和力钾转运蛋白基因HKT1的表达均影响不大,但促进了液泡膜Na^+/H^+反向转运蛋白基因NHX1的表达。对盐胁迫下黄瓜叶片Na^+的亚细胞定位发现,硅处理使叶绿体中Na^+含量下降,而液泡中Na^+含量升高。硅处理提高了盐胁迫植株根和叶片中赤霉素、生长素和细胞分裂素的水平。【结论】施硅可提高液泡膜Na^+/H^+反向转运蛋白基因NHX1的表达,将Na^+区隔化于液泡中,进而降低叶绿体中的Na^+含量,缓解盐胁迫下黄瓜幼苗的氧化损伤;硅还诱导产生了较多的赤霉素、生长素和细胞分裂素,其调控Na^+积累和黄瓜幼苗的氧化损伤的机理还需进一步研究。【Objectives】The mechanisms for Si-mediated salt tolerance vary in different plants.The effects of Si on oxidative damage,Na+accumulation and partitioning,as well as hormone levels were explored in cucumber seedlings under salt stress in this paper.【Methods】A hydroponic culture was conducted using cucumber cultivar in genotype of Mch-4 as experimental material.In the nutrient solution,the NaCl stress level was 65 mmol/L and Na2SiO3·9H2O level was 0.3 mmol/L.After the seedlings were treated for 10 days under stress,the biomass,Na+content and partitioning,the expression of Na+transport related genes and hormone levels were investigated.【Results】Addition of Si could improve the growth of cucumber seedlings and alleviate plant oxidative damage under NaCl stress.Si addition had no significant effects on Na+contents in roots and leaves,significantly reduced the expressions of plasma membrane Na+/H+antiporter gene SOS1,had no significant effects on high-affinity K+channel gene HKT1 under salt stress,while promoted the expression of vacuolar Na+/H+exchanger gene NHX1.According to the subcellular localization of Na+in leaf mesophyll cells of cucumber,silicon decreased the Na+content in chloroplasts while increased that in vacuoles under salt stress.Added silicon increased the levels of gibberellin,auxin and cytokinin in roots and leaves under salt stress.【Conclusions】Si addition could upregulate the expression of vacuolar Na+/H+exchanger gene NHX1,enhance Na+partitioning into vacuoles while reducing Na+content in chloroplasts,so alleviate oxidative damage of cucumber seedlings under salt stress.Si-induced increases in levels of gibberellin,auxin and cytokinin may be involved in regulating salt tolerance of cucumber,the mechanism needs further study.

关 键 词：盐胁迫 硅 Na^+/H^+反向转运蛋白基因NHX1 Na^+区隔化 激素 

分 类 号：S642.2[农业科学—蔬菜学]