外源蔗糖对小麦幼苗耐盐性的影响

本研究选取小麦品种"沧6001"(抗盐性品种)和"石4185"(盐敏感品种)为试验材料,采用水培方法,对加入蔗糖后两个小麦品种的耐盐性进行比较。结果表明,盐胁迫下,"沧6001"和"石4185"小麦根系生长均受到抑制,"石4185"根系受到抑制的程度大于"沧6001";蔗糖预处理可以显著缓解盐胁迫对根系生长的抑制作用。蔗糖预处理12 h后,"沧6001"和"石4185"的可溶性糖含量上升,与"石4185"相比,"沧6001"具有更高的可溶性糖水平,但是蔗糖预处理后"石4185"可溶性糖含量的增加量高于"沧6001"。H2DCFDA荧光探针检测和PI荧光染色检测结果表明,蔗糖预处理可有效降低盐胁迫下小麦幼苗体内活性氧累积水平,保护细胞膜的完整性并减小根尖细胞死亡率。蔗糖预处理可以提高小麦幼苗SOD和APX(P<0.05)、CAT活性(P>0.05)。本研究对于理解外源物质对小麦耐盐性影响的生理机制及筛选耐盐性的小麦品种具有指导意义。

Effect of exogenous sucrose application on wheat seedling salt tolerance

The objective of this study was to elucidate the role of exogenous sucrose in enhancing salt tolerance of "Cang 6001"(salt-tolerant) and "Shi 4185"(salt-sensitive) wheat(Triticum aestivum L.) cultivars.Root elongation,soluble sugar content,ROS(reactive oxygen species) level and antioxidant defense reaction were examined in wheat grown in nutrient solutions with/without NaCl(150 mmol·L-1) and/or sucrose(80 mmol·L-1).The salt treatment induced significant inhibitory effects on plant growth.Root elongation was obviously(P < 0.05) restrained by treatment with 150 mmol·L-1 NaCl.Compared with "Cang 6001","Shi 4185" seedlings were inhibited more significantly.The inhibition effects were somehow weakened by exogenous sucrose application.Ex-ogenous sucrose obviously increased total soluble sugar contents in both "Cang 6001" and "Shi 4185" wheat cultivars.The increment in soluble sugar content in "Cang 6001" was less than that in "Shi 4185",while "Shi 4185" contained less soluble sugar than "Cang 6001" under no exogenous sucrose application.Results of H2DCFDA fluorescence probe and fluorescence staining tests showed that exogenous sucrose pretreatment effectively decreased ROS(reactive oxygen species) level and consequently maintaining cell mem-brane integrity and decreasing root-tip cell mortality.Exogenous sucrose pretreatment also enhanced leaf SOD(P < 0.05),APX(P < 0.05) and CAT(P > 0.05) activities in both cultivars.It was concluded that exogenous sucrose increased wheat seedling salt tolerance.Put together,the results suggested that sucrose-mediated salt toxicity alleviation depended mainly on sucrose-mediated antioxidant defense capacity and membrane integrity.This study was positively significant for further understanding of physiological mecha-nisms of exogenous substances that drove wheat response to salt stress and screening wheat cultivars for high salt tolerance.