Draft Genome Sequence Resource for Phyllachora maydis—An Obligate Pathogen That Causes Tar Spot of Corn with Recent Economic Impacts in the United States

Abstract

Phyllachora maydis is an important fungal pathogen that causes tar spot of corn and has led to significant yield loss in the United States and other countries. P. maydis is an obligate biotroph belonging to the Sordariomycetes class of Ascomycota. Due to the challenges posed by their obligate nature, there is no genome sequence available in the Phyllachora genus. P. maydis isolate PM01 was collected from a corn field in Indiana and the genome was determined by next-generation sequencing. The assembly size is 45.7 Mb, with 56.46% repetitive sequences. There are 5,992 protein-coding genes and 59 are predicted as effector proteins. This genome resource will increase our understanding of genomic features of P. maydis and will assist in studying the corn–P. maydis interaction and identifying potential resistant candidates for corn breeding programs.

Tar Spot of Maize: Current knowledge of genetic interactions and future research prospects to improve disease resistance

“…In parallel to screening natural and artificial maize populations for new resistance alleles, additional studies should also aim to investigate the infection strategy used by P. maydis at the individual plant scale (Figure 2B). Currently, P. maydis is presumed an obligate biotrophic fungal pathogen as it likely requires photosynthetically active tissue for survival and is unable to be cultured in the laboratory (Rocco da Silva et al, 2021;Telenko et al, 2020). However, P. maydis has also been shown to overwinter on maize debris in the United States (Kleczewski et al, 2019b;Groves et al, 2020), suggesting it can survive as a saprophyte and may exhibit a bi-phasic lifestyle.…”

“…Characterize P. maydis virulence (effector) proteins and their host targets in maize Virulence proteins translocated by fungal pathogens often have a functional role in promoting plant disease either by suppressing or activating host immune responses and, therefore, can serve as important resources for introducing novel host resistance specificities (Figueroa et al, 2021). Though P. maydis is predicted to secrete effector proteins (Telenko et al, 2020), our general understanding of howP. maydis utilizes its effector repertoire for virulence as well as their host targets in maize remain unknown.…”

“…maydis utilizes its effector repertoire for virulence as well as their host targets in maize remain unknown. Such studies are complicated by the observation that P. maydis is genetically intractable and culturing of this pathogen has not been successful (Rocco da Silva et al, 2021;Telenko et al, 2020). Hence, genetic manipulation of the fungal pathogen is not yet possible.…”

Taxonomy, Phylogenetic and Ancestral Area Reconstruction in Phyllachora, with Four Novel Species from Northwestern China

“…Some members of the genus can inflict crop diseases, leading to yield loss. Phyllachora maydis is an example occurring in the United States, which can seriously impact quality and corn yield [ 21 , 22 , 23 , 24 ]. Owing to its biotrophic habit and high degree of host specificity, most Phyllachora species are given names based on host association and coevolution with the host [ 5 , 8 , 20 , 25 ].…”

Candidate effector proteins from the maize tar spot pathogenPhyllachora maydislocalize to diverse plant cell compartments

“…To gain initial insights into P. maydis virulence mechanisms, Telenko and colleagues provided its first draft genome sequence (Telenko et al, 2020). Analysis of the P. maydis genome revealed 462 proteins comprising the predicted secretome, of which 59 contain effector-like sequence characteristics as predicted by EffectorP (v2.0) (Telenko et al, 2020).…”