玉米对镉胁迫的响应及其耐镉机制研究进展

Responses of Maize to Cadmium Stress and Mechanisms of Cadmium Tolerance

近年来,土壤重金属污染已成为严重的环境问题,对作物生产、粮食安全和人类健康构成巨大威胁。镉(Cd)由于在环境中具有潜在的毒性和高流动性,使其成为重金属中毒性最大、分布最广泛的污染物之一。玉米作为我国和世界上主要的农作物,具有生物量大,叶片、茎秆Cd富集能力高,其向籽粒转运能力较低的特点,是比较理想的Cd污染土壤修复植物。玉米生长会受到Cd胁迫浓度、胁迫时期及环境条件的影响,且品种间存在差异,不同品种对Cd毒害的耐受性不同。本文在介绍玉米对Cd吸收、转运方式及其在不同器官分布的基础上,着重阐述了Cd对玉米生长发育和对水分代谢、矿质养分代谢、光合作用和呼吸作用等主要代谢过程的影响;并从耐逆性和避逆性两方面探讨了玉米对Cd的耐受机制。结合已有研究发现,现阶段主要以不同玉米品种对Cd胁迫的生理生化响应及其耐Cd差异比较研究为主,对其存在差异的生理、尤其分子机制还缺乏深入研究;同时,对玉米Cd耐受性评价标准不一致,是以生长受到影响的程度还是以器官中镉含量作为品种对镉耐受性的判断标准还有待于商榷。未来这些问题的解决将为利用生物技术手段培育适合不同Cd污染区域的玉米品种,实现玉米产业的可持续发展奠定基础。

In recent years,soil heavy metal pollution has become a serious environmental problem,and it has posed a huge threat to crop production,food security and human health.Cadmium(Cd)is potential toxicity and high liquidity in the environment,which make it one of the most toxic and widely distributed pollutants of heavy metals.Maize,as a main crop in China and the world,with high biomass,high Cd enrichment ability of leaves and stems,and low transfer capacity to grain,has been considered as an ideal Cd contaminated soil remediation plant.Maize growth is affected by Cd stress concentration,stress period and environmental conditions,and there are differences among varieties.Different varieties have different tolerances to Cd toxicity.This paper reviewed the effects of Cd on the growth and development of maize and its main metabolic processes,such as water metabolism,mineral nutrient metabolism,photosynthesis and respiration,based on the introduction of Cd uptake and transport in maize and its distribution in different organs.The tolerance mechanism of maize to Cd was discussed from the aspects of tolerance and avoidance.Combined with previous studies,it is found that the physiological and biochemical responses of Cd stress and the difference of Cd tolerance in different maize varieties are mainly studied at this stage.The physiological and especially molecular mechanisms of the differences are still not studied in depth.At the same time,the evaluation criteria for the tolerance of Cd to maize are inconsistent.Whether the growth is affected or the cadmium content in the organ as the criterion for the tolerance of cadmium remains to be discussed.The solution to these problems in the future will lay the foundation for the use of biotechnology to cultivate maize varieties suitable for different Cd-contaminated areas and achieve sustainable development of the maize industry.