镉胁迫下小麦根系分泌物的变化

通过水培和砂培两种方法 ,研究了镉胁迫下小麦 ( Triticum aestivm L.)根系分泌物变化。通过研究镉对小麦根系分泌氨基酸和糖 ,根系分泌其它一些次生代谢物质等的影响 ,以及根系分泌物对蔬菜种子萌发的影响 ,探讨镉胁迫下植物根系的生理生态效应。研究结果表明 :镉胁迫下 ,小麦根系分泌物无论在量上还是质上都有变化。镉胁迫下根系分泌的电解质、糖类、氨基酸以及其它一些次生代谢物质都有所变化 ,但变化情况有差异。电解质外渗率、糖类随 Cd2 + 浓度升高而增加 ,在低浓度 Cd2 + 作用下 ( 0 .5 mg/ L) ,随处理浓度的升高 ,氨基酸分泌量增加 ;当处理浓度高于相应浓度时 ,氨基酸分泌量随浓度升高而减少。随 Cd2 + 浓度升高 ,次生代谢物分泌种类减少。这说明小麦通过改变根分泌作用而缓解镉危害。由于根系分泌次生代谢物的活动比较复杂 ,因而根系的分泌作用有待于进一步研究。根系分泌物中可能含有某些物质抑制萝卜、白菜种子萌发 ,这是涉及到植物他感作用的问题 ,值得并有待于进一步研究。初步分析小麦根系在不同的环境中对镉胁迫的响应方式 ,为以后根分泌物的深入研究提供了一定的思路 ,也为镉污染区农作物的合理栽培提供新的参考资料。

Changes of Root Exudates to Cadmium Stress in Wheat (Triticum aestivm L.)

Most of the areas in farmlands is polluted by cadmium(Cd).It will be harmful to human being by food cycles.It is important to study the effects of Cd on crops.The aim of the study presented here was to determine the effects of Cd on wheat(Triticum aestium L.),a common crop planted in China.The study was carried out in the laboratory.Two culturing modes,water-culture medium and sand-culture medium,were used to investigate the physilogical and ecological responses of wheat root exudates to cadmium pollution stress.Wheat seedlings were planted in man-made culturing apparatus.Five concentration levels of Cd,0,0.5,5,15,50mg/L,used in the experiment.Exudation of electrolyte,H\++,sugar,amino acids and other secondary metabolism products in the root were measured.Effects of the exudates on vegetable seed germination were also investigated.The results showed that Cd could affect root exudation.There were the same trends as in changes of root exudates to cadmium stress in wheat in the two culturing modes.Under the stress of Cd,root exudation in wheat changed quantitatively and qualitatively with different Cd concentration.Cd affected the exudation of electrolyte,H\++,sugar,amino acids and secondary metabolism.It showed promotive effects on the exudation of electrolyte and sugar.It showed promotive effects on the exudation of H\++ and amino acids when the cd concetration was lower than 0.5mg/L,while inhibition effects were showed when the concentration went up.The classes of components of secondary metabolism decreased when the concentration went up.Because components of the secondary metabolism were very complicated,and the changes of different classes of secondary metabolism were different,suggesting further study on the changes of its products under the stress of Cd pollution was necessary.It showed that the root exudates inhibit the germination of radish and cabbage seeds.Some components of root exudates might inhibit the germination of radish and cabbage seeds,their mechanisms were not very clear yet;this linked with allelopathy issue.Also,it is worthy to be studied further.This paper primarily provides some information on root exudation with a clue and some new references on appropriately culturing in areas polluted by Cd.