根系分泌物对根际激发效应影响的生物机制研究进展

Biological mechanism of effects of root exudates on rhizosphere priming effect:A review

  • 摘要: 土壤有机碳的动态平衡对土壤碳循环效率及全球碳循环管理具有重要意义。根系分泌物作为一类根系外源物,与土壤微生物相互作用对根际激发效应产生重要影响。文章通过分析根际激发效应的相关文献,综述了目前有关根际激发效应的研究热点、研究方向及存在的不足。根据根际激发效应的方向及强度,总结了以微生物活化理论、微生物共代谢假说和氮挖掘假说为主的正激发效应;以基质优先利用理论、养分竞争假说以及微生物残体再循环理论为主的负激发效应以及以化学计量比理论为主的正/负激发效应的生物机理。通过分析不同根际激发效应生物机制,总结了根际激发效应的影响因素,描述了不同生物机制间的内外联系,强调微生物、胞外酶、根际养分情况、碳氮比、根系结构与分泌物种类等对根系分泌物介导激发效应的影响情况。根系分泌物与根际养分情况将与微生物的种类、活性与数量相互影响,构成了一个复杂的网络关系,最终共同决定其激发效应的方向与强度。总结出目前有关根际激发效应的研究大多集中在利用培养控制方法,通过添加简单低分子底物,如糖类、有机酸和酚酸等方法研究其对根际激发效应的影响及机制。今后需要关注真实环境条件下土壤有机碳激发效应研究方法的探究,加强对激发效应生物调控和非生物调控机制的具体研究。文章为深入研究根系分泌物引发激发效应机制,提高土壤碳循环效率,进而为实现国家“双碳”目标,推动农业高质量发展提供理论参考依据。

     

    Abstract: The dynamic balance of soil organic carbon is crucial for soil carbon cycling efficiency and global carbon cycle management. Root exudates,as root-derived external material,interact with soil microorganisms,which would exert crucial impact on the rhizosphere priming effect. By analyzing relevant literature on the rhizosphere priming effect, this article comprehensively reviewed the current research hotspots,future research directions and deficiencies regarding the rhizosphere priming effect. According to the direction and intensity of the rhizosphere priming effect,it summarized the positive priming effect mainly based on the microbial activation theory,the microbial co-metabolism hypothesis,and the nitrogen mining hypothesis;the negative priming effect mainly based on the substrate preference theory,the nutrient competition hypothesis,and the microbial residue recycling theory;and the biological mechanisms of positive/negative priming effect mainly based on the stoichiometry theory. Through analyzing the biological mechanisms of different rhizosphere priming effect,it summed up the influencing factors of the rhizosphere priming effect,described the internal and external connections among different biological mechanisms,and emphasized the impacts of microorganisms,extracellular enzymes,rhizosphere nutrient conditions,ratio of carbon to nitrogen,root structure,and types of root exudates on the priming effect mediated by root exudates. Root exudates and rhizosphere nutrient conditions would interact with the species,activity and quantity of microorganisms,forming a complex network relationship,which ultimately jointly determined the direction and intensity of the priming effect. It is concluded that most of the current researches on the rhizosphere priming effect focused on using cultivation control methods and adding simple low-molecular-weight substrates, such as sugars,organic acids and phenolic acids,to study their impacts and mechanisms on the priming effect. In the future,attention should be paid to the exploration of research methods for the soil organic carbon priming effect under real environmental conditions and strengthening specific research on the biological and non-biological regulation mechanisms of the priming effect. This article provided theoretical reference basis for in-depth research on the mechanism of the priming effect induced by root exudates,impro-ving soil carbon cycling efficiency,and further realizing the national“dual carbon”goals and promoting high-quality agricultural development.

     

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