冬小麦对过量钼胁迫的代谢响应与耐钼机制

Metabolic response and molybdenum tolerance mechanism of winter wheat to excess molybdenum stress

以正常钼与过量钼水平水培种植的冬小麦为试验材料,通过分析过量钼供给下小麦亚细胞组分钼含量及叶片代谢物的变化来探究冬小麦耐受过量钼的生理机制。结果显示,在过量钼水平下,根系亚细胞组分细胞壁、可溶性部分、细胞器、原生质体/叶绿体钼含量分别是地上部的219、38、25和62倍;根部和地上部的可溶性部分中钼的积累比例分别为71.85%和88.54%;在过量钼胁迫下小麦叶片苹果酸、延胡索酸的含量分别上升了2.08倍和2.07倍,β-丙氨酸、L-丝氨酸、L-苏氨酸、L-谷氨酰胺的含量分别上升了2.78、1.89、1.67和1.91倍。结果表明,根系具有阻控过量钼向地上部运输的作用,植物液泡是过量钼存储的主要部位,过量胁迫下产生的有机酸、氨基酸可能在液泡中与钼螯合以降低其生物毒性,增强小麦的耐过量钼能力。

Molybdenum(Mo)is one of the essential nutrient element for the plant growth,but excess Mo will cause physiological toxicity to plant.With the increase of mining area,many events of Mo pollution have been reported in the world.Meanwhile,many studies have found that some plants show strong tolerance to excessive Mo,but there are few studies on the Mo tolerance mechanisms.Therefore,we analyzed the changes of Mo content in subcellular components and leaf metabolites of wheat under excess Mo supply,and to further explore the physiological mechanism.The Mo content in cell wall,soluble part,organelle,protoplast/chloroplast of root subcellular components was 219,38,25 and 62 times higher than that in shoot respectively;The accumulation proportion of Mo in soluble fraction of root and shoot was 71.85%and 88.54%.Under excess Mo,the contents of malic acid and fumaric acid in wheat leaves were increased by 2.08 and 2.07 times,and the contents ofβ-alanine,L-serine,L-threonine and L-glutamine were increased by 2.78,1.89,1.67 and 1.91 times,respectively.These results indicate that root system can prevent and control the transportation of excess Mo to shoot,and vacuole can be the main storage site of excess Mo,and organic acids and amino acids produced may chelate with Mo in vacuole to reduce its biological toxicity.This study provided theoretical basic for the mechanism of plant tolerance to excess Mo stress,and supplied the technical support for plant remediation of soil Mo pollution.