缺Ca/Fe及盐分胁迫下番茄Pb吸收转运与关键基因的表达关系

选取台湾黄圣女番茄为供试材料,通过水培试验研究缺Ca/Fe及盐分胁迫三种处理对Pb在番茄中富集的影响,并测定不同处理下根部CNGC1(环核苷酸门控非选择性阳离子通道)和HMA3(P1B-ATPase酶)基因的相对表达量,进而探究CNGC1和HMA3基因的表达对番茄吸收累积Pb的影响。结果表明:与对照相比,缺钙处理显著增强了根对Pb的吸收能力并抑制了Pb往地上部转运过程,缺Fe处理对根吸收能力无显著影响而增加了往地上部转运量,盐分处理同时增强了根部吸收及往地上部转运能力;不同处理下番茄根部单位质量Pb净吸收量与CNGC1离子通道的活性水平呈现出极显著正相关(P0.01),说明番茄根部CNGC1离子通道在不同处理下Pb的吸收可能起着重要作用;番茄Pb转运系数与HMA3的表达量呈现极显著负相关(P0.01),说明番茄HMA3的高表达抑制了番茄对Pb的地上转运能力。因此,缺Ca/Fe及盐分胁迫处理对Pb在番茄中富集有不同影响,CNGC1离子通道和HMA3的表达量在一定程度上决定了Pb在番茄中的分布。

Relationship between expression levels of critical genes and Pb uptake and translocation by tomato exposed to Fe-deficiency, Ca-deficiency, and salinity stress

A hydroponic experiment was conducted to investigate the characteristics of lead(Pb) accumulation in tomato(Lycopersicon esculentum Mill) exposed to Fe-deficiency, Ca-deficiency, and salinity stress. The genes HMA3 and CNGC1 were located by homology comparison, and their gene expression levels in roots were determined. These results were used to discuss the effect of these two gene expressions on Pb accumulation. The results showed that:(1) Compared with control groups, the Ca-deficiency treatment significantly increased Pb uptake by roots, but inhibited root-to-shoot Pb translocation. The Fe-deficiency treatment significantly increased the amount of Pb translocation from roots to shoots but did not significantly influence root Pb uptake. The salinity treatment significantly enhanced the uptake and transportation of Pb.(2) A very significant positive correlation between Pb uptake by per unit root mass and activity level of CNGC1 cation channel was observed in the three treatments, indicating that CNGC1 cation channel played an important role in Pb uptake. Furthermore, there was a negative correlation between the expression of HMA3 and Pb translocation from roots to shoots, implying that high expression of HMA3 restricted Pb transport to the shoots. Hence, Fe-deficiency, Ca-deficiency, and salinity stress have different effects on Pb accumulation in tomato, and expression levels of HMA3 and CNGC1 control the distribution of Pb in tomato.