Deacetylation of chitin oligomers increases virulence in soil-borne fungal pathogens

First author: Feng Gao; Affiliations: CAS Institute of Microbiology (中科院微生物研究所): Beijing, China

Corresponding author: Hui-Shan Guo 

Soil-borne fungal pathogens that cause crop disease are major threats to agriculture worldwide. Here, we identified a secretory polysaccharide deacetylase (PDA1) from the soil-borne fungus Verticillium dahliae, the most notorious plant pathogen of the Verticillium genus, that facilitates virulence through direct deacetylation of chitin oligomers whose N-acetyl group contributes to host lysine motif (LysM)-containing receptor perception for ligand-triggered immunity. Polysaccharide deacetylases are widely present in fungi, bacteria, insects and marine invertebrates and have been reported to possess diverse functions in developmental processes rather than virulence. A phylogenetics analysis of more than 5,000 fungal proteins with conserved polysaccharide deacetylase domains showed that the V. dahliae PDA1-containing subtree includes a large number of proteins from the Verticillium genus as well as the Fusarium genus, another group of characterized soil-borne fungal pathogens, suggesting that soil-borne fungal pathogens have adopted chitin deacetylation as a major virulence strategy. We showed that a Fusarium PDA1 is required for virulence in cotton plants. This study reveals a substantial virulence function role of polysaccharide deacetylases in pathogenic fungi and demonstrates a subtle mechanism whereby deacetylation of chitin oligomers converts them to ligand-inactive chitosan, representing a common strategy of preventing chitin-triggered host immunity by soil-borne fungal pathogens.

土壤传播的真菌病原体会导致作物病害，因而是全球农业的主要威胁。本文中，作者从土传病菌大丽轮枝菌中鉴定了一种分泌性多糖脱乙酰基酶PDA1，该菌是轮枝菌属中最臭名昭著的植物病原体，可通过对几丁质低聚物的直接脱乙酰作用促进毒力，而几丁质低聚物中的N-乙酰基团作用于宿主的含有赖氨酸基序LysM受体感知以诱导配体触发的寄主免疫。多糖脱乙酰酶广泛存在于真菌、细菌、昆虫和海洋无脊椎动物中，在发育过程中具有多种功能，而不是具有毒性。对具有保守多糖脱乙酰基酶结构域的5000多种真菌蛋白的系统发育分析表明，包含大丽轮枝菌PDA1的进化枝含有大量来自轮枝菌属和镰刀菌属的蛋白质，而镰刀菌属则是另一类典型的土传真菌病原体，这表明土传的真菌病原体已采用几丁质脱乙酰化作为主要的毒力策略。作者的研究表明，镰刀菌属PDA1是侵染棉花所必需的。这项研究揭示了多糖脱乙酰酶在致病真菌中的重要毒力功能作用，并证明了几丁质低聚物的脱乙酰作用使其转化为配体非活性的几丁聚糖的巧妙机制，这代表了预防由土传真菌病原体导致的几丁质诱导型宿主免疫的常见策略。

通讯：郭惠珊  (http://www.im.cas.cn/jgsz2018/yjtx/zwjyzxgjzdsys/201811/t20181109_5168608.html)

个人简介：1983-1987年，中山大学，学士；1993-1996年，西班牙马德里大学，博士；1997-1998年，西班牙马德里大学，博士后。

研究方向：1. 植物RNA沉默的分子机制及其抗病应用研究； 2. 植物与真菌的互作机理及维管束真菌病害的防控策略研究。

doi: https://doi.org/10.1038/s41477-019-0527-4

Journal: Nature Plants

Published date: October 21, 2019