Zou Jingwen, Du Yanfei, Xing Xiaoxing, Huang Panpan, Wang Zeyi, Liu Huiquan, Wang Qinhu, Xu JinRong
State Key Laboratory of Crop Stress Biology for Arid Areas and NWAFU-Purdue Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, 712100, Shaanxi, China.
Dept. of Botany and Plant Pathology, Purdue University, West Lafayette, 47907, IN, USA.
Stress Biol. 2024 Jun 12;4(1):30. doi: 10.1007/s44154-024-00174-w.
Although genome-wide A-to-I editing mediated by adenosine-deaminase-acting-on-tRNA (ADAT) occurs during sexual reproduction in the presence of stage-specific cofactors, RNA editing is not known to occur during vegetative growth in filamentous fungi. Here we identified 33 A-to-I RNA editing events in vegetative hyphae of Fusarium graminearum and functionally characterized one conserved hyphal-editing site. Similar to ADAT-mediated editing during sexual reproduction, majority of hyphal-editing sites are in coding sequences and nonsynonymous, and have strong preference for U at -1 position and hairpin loops. Editing at TAG, one of the hyphal-specific editing sites, is a premature stop codon correction (PSC) event that enables CHE1 gene to encode a full-length zinc fingertranscription factor. Manual annotations showed that this PSC site is conserved in CHE1 orthologs from closely-related Fusarium species. Whereas the che1 deletion and CHE1 (G to A) mutants had no detectable phenotype, the CHE1 (A to G) mutant was defective in hyphal growth, conidiation, sexual reproduction, and plant infection. However, the CHE1 mutant was increased in tolerance against oxidative stress and editing of TAG in CHE1 was stimulated by HO treatment in F. graminearum. These results indicate that fixation of the premature stop codon in CHE1 has a fitness cost on normal hyphal growth and reproduction but provides a benefit to tolerance against oxidative stress. Taken together, A-to-I editing events, although rare (not genome-wide), occur during vegetative growth and editing in CHE1 plays a role in response to oxidative stress in F. graminearum and likely in other fungal pathogens.
虽然由作用于tRNA的腺苷脱氨酶（ADAT）介导的全基因组A到I编辑在有阶段特异性辅因子存在的有性生殖过程中发生，但丝状真菌营养生长期间的RNA编辑尚不清楚。在这里，我们在禾谷镰刀菌的营养菌丝中鉴定出33个A到I RNA编辑事件，并对一个保守的菌丝编辑位点进行了功能表征。与有性生殖期间ADAT介导的编辑类似，大多数菌丝编辑位点位于编码序列中且为非同义突变，并且在-1位置对U和发夹环有强烈偏好。菌丝特异性编辑位点之一TAG处的编辑是一个提前终止密码子校正（PSC）事件，使CHE1基因能够编码全长锌指转录因子。人工注释表明，这个PSC位点在密切相关的镰刀菌属物种的CHE1直系同源物中是保守的。虽然che1缺失突变体和CHE1（G到A）突变体没有可检测到的表型，但CHE1（A到G）突变体在菌丝生长、分生孢子形成、有性生殖和植物感染方面存在缺陷。然而，CHE1突变体对氧化应激的耐受性增加，禾谷镰刀菌中HO处理可刺激CHE1中TAG的编辑。这些结果表明，CHE1中提前终止密码子的固定对正常菌丝生长和繁殖有适应性代价，但对氧化应激耐受性有好处。综上所述，A到I编辑事件虽然罕见（非全基因组范围），但在营养生长期间发生，CHE1中的编辑在禾谷镰刀菌以及可能在其他真菌病原体对氧化应激的反应中发挥作用。
