title: Sequencing of the Litchi Downy Blight Pathogen Reveals It Is a Phytophthora Species With Downy Mildew-Like Characteristics.
abstract: On the basis of its downy mildew-like morphology, the litchi downy blight pathogen was previously named Peronophythora litchii. Recently, however, it was proposed to transfer this pathogen to Phytophthora clade 4. To better characterize this unusual oomycete species and important fruit pathogen, we obtained the genome sequence of Phytophthora litchii and compared it to those from other oomycete species. P. litchii has a small genome with tightly spaced genes. On the basis of a multilocus phylogenetic analysis, the placement of P. litchii in the genus Phytophthora is strongly supported. Effector proteins predicted included 245 RxLR, 30 necrosis-and-ethylene-inducing protein-like, and 14 crinkler proteins. The typical motifs, phylogenies, and activities of these effectors were typical for a Phytophthora species. However, like the genome features of the analyzed downy mildews, P. litchii exhibited a streamlined genome with a relatively small number of genes in both core and species-specific protein families. The low GC content and slight codon preferences of P. litchii sequences were similar to those of the analyzed downy mildews and a subset of Phytophthora species. Taken together, these observations suggest that P. litchii is a Phytophthora pathogen that is in the process of acquiring downy mildew-like genomic and morphological features. Thus P. litchii may provide a novel model for investigating morphological development and genomic adaptation in oomycete pathogens.
authors.affiliation: 1 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China;
authors.forename: Wenwu
authors.initials: W
authors.lastname: Ye
authors.affiliation: 1 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China;
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: 1 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China;
authors.forename: Danyu
authors.initials: D
authors.lastname: Shen
authors.affiliation: 1 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China;
authors.forename: Delong
authors.initials: D
authors.lastname: Li
authors.affiliation: 1 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China;
authors.forename: Tianhuizi
authors.initials: T
authors.lastname: Pu
authors.affiliation: 3 Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Zide
authors.initials: Z
authors.lastname: Jiang
authors.affiliation: 1 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China;
authors.forename: Zhengguang
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: 1 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China;
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Zheng
authors.affiliation: 2 Center for Genome Research and Biocomputing, and Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, U.S.A.; and.
authors.forename: Brett M
authors.initials: BM
authors.lastname: Tyler
authors.affiliation: 1 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China;
authors.forename: Yuanchao
authors.initials: Y
authors.lastname: Wang
mesh_terms: D001483:Base Sequence; D005638:Fruit / Q000469:parasitology; D023281:Genomics; D032125:Litchi / Q000469:parasitology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010838:Phytophthora / Q000145:classification* / Q000235:genetics / Q000502:physiology; D010935:Plant Diseases / Q000469:parasitology*; D017434:Protein Structure, Tertiary; D017422:Sequence Analysis, DNA