缺氧和充氧栽培对水稻Cd积累及OsHMA2基因表达的影响

【目的】研究缺氧和充氧栽培对水稻重金属Cd的吸收和转运及OsHMA2基因在茎中表达的影响,为降低水稻中重金属的吸收和累积奠定基础。【方法】以水稻品种五丰优2168为试验材料,通过营养液缺氧和营养液充氧的水培盆栽试验,分析Cd质量浓度为0、0.6、1.2mg·L~(-1)时,Cd的吸收累积以及茎中OsHMA2基因表达水平。【结果】缺氧栽培条件下,水稻生长发育受Cd抑制作用不显著,而充氧栽培条件下水稻生长受到显著抑制,表现为根、地上部干质量显著下降。在0.6和1.2mg·L~(-1)Cd处理条件下,缺氧栽培的水稻根部和地上部Cd累积量均低于充氧栽培。2种栽培条件下,根部Cd累积量均随Cd处理浓度的增大而增大。水稻地上部对Cd的累积在缺氧栽培条件下,0.6和1.2mg·L~(-1)Cd处理无显著差异,充氧栽培的水稻地上部Cd累积随处理浓度增大而增大。与对照相比,水稻茎OsHMA2表达量在缺氧和充氧栽培下,0.6mg·L~(-1)Cd处理上调,而1.2mg·L~(-1)Cd处理下调;在Cd处理下,OsHMA2表达量缺氧栽培高于充氧栽培。【结论】缺氧栽培能抑制水稻对Cd的吸收和累积;Cd累积量达到一定值时能够下调OsHMA2的表达。

Effects of anoxic and aerobic cultivation conditions on cadmium accumulation and OsHMA2 expression in rice

Objective] To study the effects of anoxic and aerobic cultivation conditions on cadmium (Cd) uptake and transfer and OsHMA2 expression in rice shoots,and provide a theoretical basis for reducing the uptake and accumulation of heavy metals in rice.Method] Using rice cultivar ‘Wufengyou 2168',pot experiments were performed hydroponically under anoxic(nutrient solution with agar) and aerobic(oxygenized nutrient solution) conditions.Cd uptake and accumulation,and OsHMA2 expression levels in rice shoots were analyzed at three Cd levels(0,0.6,1.2 mg.L-1).Result] Rice growth was not significantly inhibited by Cd under anoxic condition,but was significantly inhibited under aerobic condition with the dry weight of roots and above ground parts significantly decreased.At the Cd concentration of 0.6 and 1.2 mg·L-1,Cd accumulations in roots and above ground parts of rice under anoxic condition were lower than those under aerobic condition.Under both anoxic and aerobic conditions,Cd accumulation in roots increased with Cd concentration.For above ground parts of rice,Cd accumulation was not significantly different between 0.6 and 1.2 mg·L-1 Cd levels under anoxic condition,but increased with Cd concentration under aerobic condition.Compared with the control (0 mg·L-1 Cd),OsHMA2 expression level increased at the Cd concentration of 0.6 mg·L-1 but decreased at 1.2 mg·L-1 in shoots under both anoxic and aerobic condition,and OsHMA2 expression level in rice was higher under anoxic condition than those aerobic condition at each Cd level.Conclusion] Anoxic culture can inhibit Cd uptake and accumulation in rice,and OsHMA2 expression decreases when Cd accumulation reaches a certain value.