Low arsenate influx rate and high phosphorus concentration in wheat (Triticum aestivum L.): A mechanism for arsenate tolerance in wheat plants
Low arsenate influx rate and high phosphorus concentration in wheat (Triticum aestivum L.): A mechanism for arsenate tolerance in wheat plants
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小麦 (Triticum aestivum L.) 的低砷流入率和高磷浓度：小麦植株砷耐受性的机制
DOI：
10.1016/j.chemosphere.2018.09.090
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发表时间：
2019
期刊：
影响因子：
8.8
通讯作者：
Rengel Zed
中科院分区：
文献类型：
--
作者：
Shi Gaoling;Ma Hongxiang;Chen Yinglong;Liu Huan;Song Guicheng;Cai Qingsheng;Lou Laiqing;Rengel Zed
两种小麦（Triticum aestivumL.）以不同耐砷性的小麦品种为材料，研究了磷浓度和营养液pH对小麦幼苗砷毒性和砷吸收动力学的影响，并探讨了小麦幼苗的砷耐性机制。低pH和低磷浓度促进了小麦对砷的吸收，导致砷的高毒性。在所有处理中，耐As（V）的品种MM 45表现出比不耐As（V）的品种HM 29更高的相对根伸长，除了在100 μmol L− 1或更高的溶液P中没有记录到基因型差异。小麦幼苗对As（V）的耐性与地上部和根中的P浓度呈正相关。在短期（30 min）的As（V）吸收动力学实验中，As（V）的最大流入速率（Vmax）随溶液pH值的降低（从7.0到6.0）而增加。与HM 29相比，MM 45的Vmax虽较低，但其米氏常数（Km）在所有处理中均未超过HM 29。除HM 29在pH 7.0时有显著较高的Vmax值外，其余两个品种的Vmax值均不受磷酸盐处理的影响。两个品种的Km值增加了9- 20倍，当磷酸盐的存在，而不是缺乏从吸收溶液。本研究表明，Vmax值主要是由高pH值和As（V）的吸收Kmis主要是由磷酸盐的存在增加。降低As（V）的流入率在早期阶段和植物组织中的P浓度的增加与小麦幼苗的耐As性增加。
Two wheat (Triticum aestivumL.) cultivars differing in arsenic (As)-tolerance were used to investigate the effects of phosphorus (P) concentration and nutrient solution pH on As(V) toxicity and As(V) uptake kinetics, and to illustrate the mechanism of As(V) tolerance in wheat seedlings. Low pH and low phosphate concentration enhanced wheat uptake of As, resulting in high As toxicity. The As(V)-tolerant cultivar MM45 exhibited higher relative root elongation than non-tolerant cultivar HM29 in all treatments, except that no genotypic difference was recorded for the solution P at 100 μmol L−1or greater. Wheat seedling As(V) tolerance was positively correlated with P concentration in roots and shoots. In short-term (30 min) As(V)-uptake kinetics experiments, the maximum influx rate (Vmax) of As(V) increased with decreasing solution pH (from 7.0 to 6.0). Compared with HM29, although MM45 had lowerVmax, its Michaelis–Menten constant (Km) did not exceed that of HM29 in all treatments. TheVmaxvalues of both cultivars were not significantly affected by phosphate treatments, except for HM29 which had significantly higherVmaxvalue in the presence of phosphate at pH 7.0. TheKmvalues of the two cultivars increased by 9- to 20-fold when phosphate was present as opposed to absent from the uptake solution. This study showed that theVmaxvalues are mainly increased by high pH and As(V) uptakeKmis mainly increased by phosphate presence. Decreased As(V) influx rates during early stages and increased P concentration in plant tissues are associated with increased As tolerance in wheat seedlings.