Comparative genomic analysis revealed rapid differentiation in the pathogenicity-related gene repertoires between Pyricularia oryzae and Pyricularia penniseti isolated from a Pennisetum grass

Phytophthora capsici is an oomycete pathogen responsible for damping off, root rot, fruit rot, and foliar blight in popular vegetable and legume crops. The existence of distinct aggressiveness levels and physiological races among the P. capsici population is a major constraint to developing resistant varieties of host crops. In the present study, we compared the genomes of three P. capsici isolates with different aggressiveness levels to reveal their genomic differences. We obtained genome sequences using short-read and long-read technologies, which yielded an average genome size of 76 Mbp comprising 514 contigs and 15,076 predicted genes. A comparative genomic analysis uncovered the signatures of accelerated evolution, gene family expansions in the pathogenicity-related genes among the three isolates. Resequencing two additional P. capsici isolates enabled the identification of average 1,023,437 SNPs, revealing the frequent accumulation of non-synonymous substitutions in pathogenicity-related gene families. Furthermore, pathogenicity-related gene families, cytoplasmic effectors and ATP binding cassette (ABC) transporters, showed expansion signals in the more aggressive isolates, with a greater number of non-synonymous SNPs. This genomic information explains the plasticity, difference in aggressiveness levels, and genome structural variation among the P. capsici isolates, providing insight into the genomic features related to the evolution and pathogenicity of this oomycete pathogen.

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Comparative genomic analysis revealed rapid differentiation in the pathogenicity-related gene repertoires betweenPyricularia oryzaeandPyricularia pennisetiisolated from aPennisetumgrass

10.1101/360016 ◽

2018 ◽

Author(s):

Huakun Zheng ◽

Zhenhui Zhong ◽

Mingyue Shi ◽

Limei Zhang ◽

Lianyu Lin ◽

...

Keyword(s):

Genetic Study ◽

Genomic Sequence ◽

Genomic Analysis ◽

Comparative Genomic Analysis ◽

Blast Disease ◽

Individual Species ◽

Comparative Genomic ◽

Phylogenomic Analysis ◽

Avirulence Genes ◽

Related Gene

AbstractBackgroundsPyriculariais a multispecies complex that could infect and cause severe blast disease on diverse hosts, including rice, wheat and many other grasses. Although the genome size of this fungal complex is small [~40 Mbp forPyricularia oryzae(syn.Magnaporthe oryzae), and ~45 Mbp forP. grisea], the genome plasticity allows the fungus to jump and adapt to new hosts. Therefore, deciphering the genome basis of individual species could facilitate the evolutionary and genetic study of this fungus. However, except for theP. oryzaesubgroup, many other species isolated from diverse hosts, such as thePennisetumgrasses, remain largely uncovered genetically.ResultsHere, we report the genome sequence of a pyriform-shaped fungal strainP. pennisetiP1609 isolated from aPennisetumgrass (JUJUNCAO) using PacBio SMRT sequencing technology. We performed a phylogenomic analysis of 28 Magnaporthales species and 5 non-Magnaporthales species and addressed P1609 into aPyriculariasubclade that is distant fromP. oryzae. Comparative genomic analysis revealed that the pathogenicity-related gene repertoires were fairly different between P1609 and theP. oryzaestrain 70-15, including the cloned avirulence genes, other putative secreted proteins, as well as some other predictedPathogen-Host Interaction(PHI) genes. Genomic sequence comparison also identified many genomic rearrangements.ConclusionTaken together, our results suggested that the genomic sequence of theP. pennisetiP1609 could be a useful resource for the genetic study of thePennisetum-infectingPyriculariaspecies.

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