The responses of poplars to fungal pathogens: A review of the defensive pathway

Abstract

Long-lived tree species need to cope with changing environments and pathogens during their lifetime. Fungal diseases cause damage to trees growth and forest nurseries. As model system for woody plants, poplars are also hosts of a large variety of fungus. The defense strategies to fungus are generally associated with the type of fungus, therefore, the defense strategies of poplar against necrotrophic and biotrophic fungus are different. Poplars initiate constitutive defenses and induced defenses based on recognition of the fungus, hormone signaling network cascades, activation of defense-related genes and transcription factors and production of phytochemicals. The means of sensing fungus invasion in poplars are similar with herbs, both of which are mediated by receptor proteins and resistance (R) proteins, leading to pattern-triggered immunity (PTI) and effector-triggered immunity (ETI), but poplars have evolved some unique defense mechanisms compared with Arabidopsis due to their longevity. In this paper, current researches on poplar defensive responses to necrotrophic and biotrophic fungus, which mainly include the physiological and genetic aspects, and the role of noncoding RNA (ncRNA) in fungal resistance are reviewed. This review also provides strategies to enhance poplar disease resistance and some new insights into future research directions.

The transcriptional landscape of Populus pattern/effector‐triggered immunity and how PagWRKY18 involved in it

“…How then do trees maintain their vigor in the face of persistent and evolving pathogen attacks over time? Recent studies have shown that poplars compared with Arabidopsis have evolved some unique defense mechanisms due to their longevity (Ullah et al, 2022; Zeng et al, 2023), but have so far received little attention in unique immune mechanisms of these perennials. In Arabidopsis , NPR1 is the master regulator of SA signalling for PR gene induction (Yu et al, 2001).…”

Editing Metabolism, Sex, and Microbiome: How Can We Help Poplar Resist Pathogens?

“…However, like any other plants, including those of cultural importance, poplars are susceptible to various diseases caused by fungal, bacterial and viral pathogens that serve as natural regulators of ecological systems [24,25]. However, this fact imposes limitations on the practical use of poplars, as damage to leaves, wood and other parts of the trees contributes to reduced growth rate and increased mortality.…”

Effect of Oak Powdery Mildew on Ascorbate–Glutathione Cycle and Other Antioxidants in Plant—Erysiphe alphitoides Interaction

“…To overcome pathogens, plants have developed various defence mechanisms and many physio-biochemical strategies to protect themselves against their attack [ 12 ]. One of the defence mechanisms of plants, including trees, against disease is the accumulation of phenolic compounds such as lignin, which increases during plant-pathogen interactions [ 13 , 14 ]. Plants accumulate cell wall aposites at sites of invasion by biotrophic fungi.…”

“…ROS may promote the biosynthesis and accumulation of salicylic acid (SA), which is involved in the induction of systemic acquired resistance (SAR) in plants. SA plays an essential role in the signalling activated by plant pathogen-associated molecular patterns (PAMPs) [ 14 , 18 , 19 ]. Stress-activated increases in the content of phytohormones such as jasmonic acid (JA), ethylene (ET), and SA involved in various signalling pathways are pathogen-induced responses [ 14 , 20 , 21 ].…”

“…SA plays an essential role in the signalling activated by plant pathogen-associated molecular patterns (PAMPs) [ 14 , 18 , 19 ]. Stress-activated increases in the content of phytohormones such as jasmonic acid (JA), ethylene (ET), and SA involved in various signalling pathways are pathogen-induced responses [ 14 , 20 , 21 ]. Regarding E. alphitoides influence on Q. robur , it has been established that the pathogen may (i) disrupt chlorophyll and cell walls by degradation of cellulose and pectin, (ii) decrease physiological and antioxidative parameters and water use efficiency, (iii) increase secondary metabolites and polyamine content, (iv) as well as lipid peroxidation [ 22 , 23 ].…”