Pumpkin powdery mildew disease severity influences the fungal diversity of the phyllosphere

Abstract

Pumpkin powdery mildew disease severity influences the fungal diversity of the phyllosphere. PeerJ 6:e4559 https://doi.org/10.7717/peerj.4559Pumpkin powdery mildew disease severity influences the fungal diversity of the phyllosphere Phyllosphere microbiota play a crucial role in plant-environment interactions and are influenced by biotic and abiotic factors. However, there is little research on how pathogen s affect the microbial community. In this study, we collected 16 pumpkin (Cucurbita moschata) leaf samples showing symptoms of powdery mildew disease with different disease severity levels ranging from L1 (least severe) to L4 (most severe). We examined the fungal community structure and diversity by Illumina MiSeq sequencing of the internal transcribed spacer (ITS) region of ribosomal RNA genes. The fungal communities were dominated by members of the Basidiomycota and Ascomycota. The dominant genus was Podosphaera on the diseased leaves, which was the key pathogen responsible for the pumpkin powdery mildew. Ascomycota and Podosphaera increased in abundance as disease severity increased from L1 to L4, and were significantly more abundant than other microorganisms at disease severity L4 (P<0.05). The richness and diversity of the fungal community increased from L1 to L2, and then declined from L2 to L4, likely due to the biotic pressure at disease severity L4. Maintaining species richness in the phyllosphere will be an important part of managing disease control in this agroecological system and an essential step toward predictable biocontrol of powdery mildew in pumpkin. (Lebeda et al., 2010). 61The phyllosphere or leaf surface is an important microbial habitat for members of the major 62 bacterial and fungal groups, and Archaea (Lindow & Leveau, 2002; Lindow and Brandl, 2003).63 These microorganisms play a crucial role in helping their host against pathogens (Lacava et al., 64 2006; Mejía et al., 2008; Rajendran et al., 2008). In past years, most of the researchers focused 65 on screening plant growth-promoting microorganisms from plants which can help us manage 66 diseases (Compant et al., 2005;Everett et al., 2005;Hirano & Upper, 2000; Whipps et al., 67 2008). However, not all the microbes in the natural environment are considered culturable. In the 68 past few years, the development of next-generation rRNA sequencing techniques has enabled us 69 to obtain in-depth descriptions of the composition of the microbial communities associated with 70 leaves of Arabidopsis thaliana (Reisberg et al., 2013), potatoes (Becker et al., 2008), rice 71 (Mwajita et al., 2012), spinach (Lopez et al., 2011 Lopez et al., 2013), grape (Leveau et al., 72 2011, and various tree species including salt cedar (Redford et al., 2010;Finkel et al., 2011). 73Historically, scholars have begun to study the rhizosphere as a microbial habitat as early as 74 100 years ago (Hartmann et al., 2008) (Zhang et al., 2014). The phyllosphere microorganisms are influenced by 82 both biotic and abiotic factors, some of which are fairly stable a...

A fungal powdery mildew pathogen induces extensive local and marginal systemic changes in theArabidopsis thalianamicrobiota

“…The analysis of powdery mildew-induced changes in plant leaf microbiota so far rests on field studies with powdery mildew-infected leaf samples (diseased leaves) in comparison to healthy/less infected leaves in Japanese spindle ( Euonymous japonicus ) (Zhang et al ., 2019b), pumpkin ( Cucurbita moschata ) (Zhang et al ., 2018) and English oak ( Quercus robur ) (Jakuschkin et al ., 2016) (reviewed in (Panstruga & Kuhn, 2019)). In the E. japonicus study, the authors noticed a reduction in bacterial and fungal diversity, associated with a general decrease in relative abundance (RA) at the genus level (Zhang et al ., 2019b).…”

“…Similarly, the richness and diversity of the fungal community was found to be reduced in pumpkin leaves heavily infected by powdery mildew ( Podospharea sp.) (Zhang et al ., 2018). Marked changes in the composition of foliar fungal and bacterial communities were also observed in Erysiphe alphitoides-colonized oak (Jakuschkin et al ., 2016).…”

Heterogeneity of the rice microbial community of the Chinese centuries‐old Honghe Hani rice terraces system

“…Another factor that could have contributed to environmental heterogeneity is the presence of rice pathogens. Several recent studies have indicated both that the impact of microbial communities on the course and outcome of host diseases can be substantial, and that host diseases can reciprocally have a large impact on microbial community compositions (Berendsen et al ., 2012; Ritpitakphong et al ., 2016; Koskella et al ., 2017; Zhang et al ., 2018; Vannier et al ., 2019). We have recently shown that the SRBSDV was prevalent in 2016 in the Malizhai HHRTS and that 23 of the 166 rice plants examined in the present study were infected by SRBSDV (Alonso et al ., 2019).…”