AUTHOR=Huang Yu , Wang Han-Cheng , Cai Liu-Ti , Li Wenhong , Pan Daiwei , Xiang Ligang , Su Xiankun , Li Zhong , Adil Muhammad Faheem , Shamsi Imran Haider 

TITLE=Phyllospheric Microbial Composition and Diversity of the Tobacco Leaves Infected by Didymella segeticola

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.699699

DOI=10.3389/fmicb.2021.699699

ISSN=1664-302X

ABSTRACT=<p>A Myriad of biotic and abiotic factors inevitably affects the growth and production of tobacco (<italic>Nicotiana tabacum</italic> L.), which is a model crop and sought-after worldwide for its foliage. Among the various impacts the level of disease severity poses on plants, the influence on the dynamics of phyllospheric microbial diversity is of utmost importance. In China, recurring reports of a phyto-pathogen, <italic>Didymella segeticola</italic>, a causal agent of tobacco leaf spot, accentuate the need for its in-depth investigation. Here, a high-throughput sequencing technique, IonS5<sup>TM</sup>XL was employed to analyze tobacco leaves infected by <italic>D. segeticola</italic> at different disease severity levels, ranging from T1G (least disease index) to T4G (highest disease index), in an attempt to explore the composition and diversity of phyllospheric microbiota. In all healthy and diseased tobacco leaves, the most dominant fungal phylum was Ascomycota with a high prevalence of genus <italic>Didymella</italic>, followed by <italic>Boeremia</italic>, <italic>Meyerozyma</italic> and <italic>Alternaria</italic>, whereas in the case of bacterial phyla, Proteobacteria was prominent with <italic>Pseudomonas</italic> being a predominant genus, followed by <italic>Pantoea</italic>. The relative abundance of fungi, i.e., <italic>Didymella</italic> and <italic>Boeremia</italic> (Ascomycota) and bacteria, i.e., <italic>Pseudomonas</italic> and <italic>Pantoea</italic> (Proteobacteria) were higher in diseased groups compared to healthy groups. Healthy tissues exhibited relatively rich and diverse fungal communities in contrast with diseased groups. The infection of <italic>D. segeticola</italic> had a complex and significant effect on fungal as well as bacterial alpha diversity. FUNGuild analysis indicated that the relative abundance of pathotrophs and saprotrophs in diseased tissues proportionally increased with disease severity. PICRUSt analysis of diseased tissues indicated that the relative abundance of bacterial cell motility and membrane transport-related gene sequences elevated with an increase in disease severity from T1G to T3G and then tended to decrease at T4G. Conclusively, the current study shows the typical characteristics of the tobacco leaf microbiome and provides insights into the distinct microbiome shifts on tobacco leaves infected by <italic>D</italic>. <italic>segeticola.</italic></p>