Induced Systemic Resistance by Beneficial Microbes

发布日期：2020-01-18 14:49 来源：网络作者：网络浏览次数：

Corné M.J. Pieterse,1,* Christos Zamioudis,1,* Roeland L. Berendsen,1 David M. Weller,1,2 Saskia C.M. Van Wees,1 and Peter A.H.M. Bakker1

Abstract

Beneficial microbes in the microbiome of plant roots improve plant health. Induced systemic resistance (ISR) emerged as an important mechanism by which selected plant growth–promoting bacteria and fungi in the rhizosphere prime the whole plant body for enhanced defense against a broad range of pathogens and insect herbivores. A wide variety of root-associated mutualists, including Pseudomonas, Bacillus, Trichoderma, and mycorrhiza species sensitize the plant immune system for enhanced defense without directly activating costly defenses. This review focuses on molecular processes at the interface between plant roots and ISR-eliciting mutualists, and on the progress in our understanding of ISR signaling and systemic defense priming. The central role of the root-specific transcription factor MYB72 in the onset of ISR and the role of phytohormones and defense regulatory proteins in the expression of ISR in aboveground plant parts are highlighted. Finally, the ecological function of ISR-inducing microbes in the root microbiome is discussed.

Keywords

defense priming, plant immunity, plant growth–promoting microbes, rhizosphere microbiome, root signaling

Schematic representation of biologically induced resistance triggered by pathogen infection (red arrow), insect herbivory (blue arrow), and colonization of the roots by beneﬁcial microbes ( purple arrows). Induced resistance involves long-distance signals that are transported through the vasculature or as airborne signals, and systemically propagate an enhanced defensive capacity against a broad spectrum of attackers in still healthy plant parts. Consequently, secondary (2◦) pathogen infections or herbivore infestations of induced plant tissues cause signiﬁcantly less damage than those in primary (1◦) infected or infested tissues.