植物激素响应和调控丛枝菌根共生研究进展

摘要

【目的】丛枝菌根是土壤中的丛枝菌真菌（arbuscular mycorrhizal, AM）与大多数陆地植物根系形成的互惠共生体。丛枝菌根的形成过程是一系列信号交换和转导的结果，受到很多基因的程序化表达调控。植物激素作为重要的信号物质被证实能够参与调控植物与AM真菌的互作过程。本文简述了植物激素在调控丛枝菌根形成的作用机理，为激素调控丛枝菌根形成的研究与应用提供理论线索。【主要进展】外源施加低浓度的生长素和脱落酸能够促进丛枝菌根共生,而外源施加赤霉素能够显著抑制丛枝菌根中丛枝的形成；内源缺失赤霉素，脱落酸以及油菜素内酯会抑制丛枝菌根共生；茉莉酸合成突变体推迟丛枝菌根形成；独脚金内酯合成、转运以及受体突变体都会抑制丛枝菌根共生；生长素以及脱落酸受体表达量降低会抑制丛枝菌根共生。但是生长素信号受体的降低表达不仅能够显著抑制丛枝菌根的形成还能显著抑制丛枝细胞的正常发育，而植物脱落酸信号受体表达降低突变体中丛枝细胞发育正常。【研究展望】激素如何调控丛枝菌根共生的研究仍处于起步阶段。随着转基因和基因编辑技术（如Crispr/cas9系统介导的基因敲除技术）的快速发展以及通过菌根植物的基因组、转录组、蛋白质和代谢组数据的挖掘，丛枝菌根共生中的众多科学问题以及与其他植物-微生物互作系统等问题都将一一得到解答。%[Objectives]Arbuscular mycorrhizal (AM) symbiosis that is formed by AM fungi in soil and most land plants is the most widespread mutualistic association in nature. The establishment of AM symbiosis involves complicated pathways of signal exchange and transduction, which are regulated by many genes with stringent and coordinated expression procedures. Plant hormones are well known to be signaling molecules that act in almost all physiological processes during plant growth and development, and also have been demonstrated to play crucial roles in modulating interactions between plants and microbe, including the AM fungi. In this article, the research progresses on the phytohormone-mediated regulation of AM symbiosis in last decade were reviewed.[Major advances]External application of low concentration of both auxin and abscisic acid improved the formation of AM symbiosis, while endogenous lack of gibberellin, abscisic acid and brassinolide repressed mycorrhization. Mutants with defection in jasmonic acid biosynthesis retarded AM fungal colonization, and knock down of the receptors of strigoloctone, auxin and abscisic acid inhibited AM symbiosis. Notably, the repressed expression of receptor of auxin not only decreased the AM colonization, but also inhibited the arbuscule abundance in cortical cells.[Expectations]The current research regarding the molecular mechanisms underlying the phytohormone-mediated regulation in the establishment of AM symbiosis is still in the early stage. With the rapid development of transgenic and gene editing techniques, such as Crispr/cas9-mediated gene knockout technology, and through the deeply mining of the genomic, transcriptomic, proteomic and metabolomics data set, the scientific questions with respect to AM symbiosis and other plant-microbial interaction systems will be finally answered.