Aaprb1, a subtilsin-like protease, required for autophagy and virulence of the tangerine pathotype of Alternaria alternata
Aaprb1, a subtilsin-like protease, required for autophagy and virulence of the tangerine pathotype of Alternaria alternata
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DOI：
10.1016/j.micres.2020.126537
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发表时间：
2020-11-01
影响因子：
6.7
通讯作者：
Li, Hongye
中科院分区：
文献类型：
--
作者：
Fu, Huilan;Chung, Kuang-Ren;Li, Hongye
病原真菌分泌的枯草杆菌蛋白酶样丝氨酸蛋白酶能促进病原真菌的感染和营养物质的获取。枯草杆菌蛋白酶样丝氨酸蛋白酶在植物病原真菌链格孢中的功能尚不清楚。在本研究中，15个枯草杆菌蛋白酶样丝氨酸蛋白酶在柑橘真菌病原体A中单独缺失。交替只有一个，指定为AaPrb 1，被发现是A所必需的。互隔致病性AaPrb1缺陷株（三角洲Aaprb1）减少生长，分生孢子，气生菌丝的形成，蛋白酶的生产，和柑橘叶片上的毒力。然而，生化分析和生物测定显示，Δ Aaprb1在ACT毒素的产生中不起作用。通过Y2H分析，发现Aaprb1与A.交替此外，沉默A. alternata导致与Delta Aaprb1相似的表型。发现AaPrb1的表达受AaPep4调节。透射电镜显示AaPrb 1和AaPep4参与了自噬体降解的抑制。自噬基因AaAtg 8在A. Alternata的孢子形成、气生菌丝的形成和致病性与Delta Aaprb1相似，表明Delta Aaprb1的某些表型可能是由于自噬功能受损所致。总的来说，这项研究扩展了我们对A。Alternata利用枯草杆菌蛋白酶样丝氨酸蛋白酶在植物宿主中实现成功感染。
Subtilisin-like serine protease secreted by pathogenic fungi can facilitate the infection and acquisition of nutrients. Functions of subtilisin-like serine proteases in the phytopathogenic fungus Alternaria alternata remains unknown. In the current study, 15 subtilisin-like serine proteases were individually deleted in the citrus fungal pathogen A. alternata. Only one, designated AaPrb1, was found to be required for A. alternata pathogenesis. The AaPrb1 deficiency strain (Delta Aaprb1) reduced growth, conidiation, the formation of aerial hyphae, protease production, and virulence on citrus leaves. However, biochemical analyses and bioassays revealed that Delta Aaprb1 plays no role in the production of ACT toxin. Through Y2H assays, Aaprb1 was found to interact with Aapep4, a vacuole-localized proteinase A in A. alternata. Furthermore, silencing AaPep4 in A. alternata resulted in phenotypes similar with those of Delta Aaprb1. Expression of AaPrb1 was found to be regulated by AaPep4. TEM showed that AaPrb1 and AaPep4 were involved in the suppression of the degradation of autophagosomes. Deletion of the autophagy gene AaAtg8 in A. alternata decreased conidiation, the formation of aerial hyphae and pathogenicity similar to Delta Aaprb1, implying that some phenotypes of Delta Aaprb1 were due to the impairment of autophagy. Overall, this study expands our understanding of how A. alternata utilizes the subtilisin-like serine protease to achieve successful infection in the plant host.