根系发育的营养调控及对其生境的影响

Nutritional control of root development and it's ecological effect

根系发育对土壤中无机营养的供应和分配的变化非常敏感,本文综述了N、P、K等营养影响根系的发育进程如分枝、根毛产生、直径、生长角度、结瘤作用和簇生根的形成等的机制.营养的供应对根系发育的影响既可以是直接的、是外部营养浓度改变的结果、也可以是间接的、是植物内部营养状况变化的结果.直接途径引起暴露在营养供应中的那部分根系的发育反应;间接途径引起系统的反应,并且似乎依赖于来自冠部的长距离的信使.讨论了最新所了解的内外营养感受 sensing 的机制,长距离信号的可能特征,激素在营养形态发生反应中的作用,根系性状的基因型差异和遗传特性,以及植物根系在生态恢复、防止环境污染、全球气候变化和资源可持续发展中的作用.

Root development is remarkably sensitive to variations in the supply and distribution of inorganic nutrients in the soil.Here we review examples of the ways in which nutrients such as N,P,K and Fe can affect developmental processes such as root branching,root hair production,root diameter,root growth angle,nodulation and proteoid root formation.The nutrient supply can affect root development either directly,as a result of changes in the external concentration of the nutrient,or indirectly through changes in the internal nutrient status of the plant.The direct pathway results in developmental responses that are localized to the part of the root exposed to the nutrient supply;the indirect pathway produces systemic responses and seems to depend on long distance signals arising in the shoot.The phloem carries a number of different kind of macromolecules,including peptide,proteins and RNAs(a kind of RNA that is phloem sapspecificed),which are potentially capable of transmitting long distance signals within the plant.So phloem enable developmental events in the various meristems of the plant to be integrated with physiological processes in the leaves.The traditional plant hormones such as auxin,cytokinin,ABA and ethylene play an important role in the trophomorphogenic response,and there is a extensive cross talk between nutrient signal transduction pathways and hormonal response pathways.It has been well know that the root development varied with species and genotype.For example,the species that bear cluster roots are more efficient in P and Fe uptake than the species that have not cluster roots.What is more,those root characteristics have a high hereditary rates,and there are many good genetic resources growing in extra environment as well.All those make it possible for ameliorating plant through genetics.In the other respect,due to the deviation of environment,resource deficiency,population exploration,it is very necessary for plant amelioration.Root characteristics not only have productive value in agriculture,but also have ecological worth.For instance,species with cluster roots are often pioneers in primary or secondary succession,and important in soil stability and community development,and show potential in bio remediation projects.Root exudation,including some organic acids,can activate the fossil coral limestone quarry or the uneasy mobile nutrition,such as P and Fe.What exudative burst taken involve a series of chemical reaction,which will have consequences for community structure and function.Nodulation is the pure and unlimited nitrogen resource on earth.It can eliminate environment pollution and release the fertilizer press as well.So there is the need to improve our understanding of root characteristic traits,development biology and ecosystem function.We also recognize,however,that root research has lagged behind its more glamorous bedfellow,shoot research,and technical difficulties in studying roots have often lain at the heart of this problem,but technology has advanced in many directions,allowing old challenges to be overcome.The rapid pace of recent and continuing developments in the molecular genetics of root development,the cloning and sequencing of membrane transporters,whole plant signaling,and ecological context all bear testimony to the dynamic and expanding character of root biology.In a word,in this review we mainly discuss what is currently known about the mechanisms of external and internal nutrient sensing,the possible nature of the longdistance signals,the role of hormones in the trophomorphogenic response,the genotype difference and genetic characteristic of roots trophomorphogenic response,and the role of roots characteristic in ecosystem rebuilding,environment pollution,climate change and sustained development of the natural resources.