土壤外源钒施加对玉米中钒积累、亚细胞分布和非蛋白巯基含量的影响

本研究旨在探讨玉米对钒(V)的耐受性机制及富集机理。采用差速离心法和DTNB5,5′-二硫代双(2-硝基苯甲酸)]比色法,研究了不同V浓度(0、100、200、300、500 mg·kg^-1)胁迫下,V在玉米中的积累、亚细胞分布和非蛋白巯基物质对V胁迫的响应。结果表明,V在玉米各部位中积累顺序为:根>叶>茎>>子实,其中74.8%~95.6%的V富集于根部。随着V胁迫浓度的增加,V的富集系数(BF)从0.061增加到0.306,而转运系数(TF)从0.336下降到0.108,从而降低了过量V对玉米茎叶的毒性。V主要积累于植物亚细胞组分的细胞壁(F1)和可溶性组分(F4)中,两者在茎叶中占总累积量的60.76%~75.75%,在根中占总累积量的82.66%~87.02%。土壤中一定的V浓度(V≤300 mg·kg^-1)可促进玉米幼苗体内非蛋白巯基(NPT)和植物螯合肽(PCs)的合成,植物也通过消耗谷胱甘肽(GSH)来合成植物螯合肽(PCs),从而降低V的毒性。因此,玉米幼苗抗V毒性的机制包括细胞壁沉积和重金属分区,以及非蛋白巯基化合物的合成。

Effects of exogenous vanadium stress on vanadium accumulation and subcellular distribution, and non-protein thiol content in maize(Zea mays L.)crops

The purpose of the present study is to investigate vanadium(V)-tolerance and-enrichment mechanisms in maize(Zea mays L.)crops. Maize seedlings were treated with varying concentrations of V(0, 100, 200, 300, and 500 mg·kg^-1)to investigate the differences in bioaccumulation and subcellular distribution of V and the responses of non-protein thiols(NPTs)to V exposure in maize seedlings by differential centrifugation and 5,5’-dithio bis-(2-nitrobenzoic acid)colorimetry, respectively. The findings revealed that V bioaccumulation in different parts of maize plants decreased in the following order:roots>leaves>stems>grains;74.8%~95.6% of V was accumulated in the roots.With an increase in V concentration, the bioconcentration factor increased from 0.061 to 0.306, whereas the translocation factor decreased from 0.336 to 0.108, thereby reducing the toxicity of excessive V to the stems and leaves of maize seedlings. V was mainly accumulated in the cell wall(F1)and soluble component(F4)of plant, both of which account for 60.76% to 75.75% of the total accumulation in the shoots, and from 82.66% to 87.02% of the total accumulation in the roots. V at certain concentrations in soil(≤300 mg·kg^-1)could promote the synthesis of NPTs and phytochelatins(PCs);plants utilize glutathione to synthesize PCs, thereby reduce the toxicity of V. Thus, the strategies employed by maize seedlings against V toxicity involve cell wall deposition, heavy metal compartmentalization, and thiol compound synthesis.