title: Versatile glycoside hydrolase family 18 chitinases for fungi ingestion and reproduction in the pinewood nematode Bursaphelenchus xylophilus.
abstract: The glycoside hydrolase family 18 (GH18) of chitinases is a gene family widely expressed in archaes, prokaryotes and eukaryotes, and hydrolyzes the β-1,4-linkages in chitin. The pinewood nematode Bursaphelenchus xylophilus is one of the organisms that produces GH18 chitinases. Notably, B. xylophilus has a higher number of GH18 chitinases compared with the obligate plant-parasitic nematodes Meloidogyne incognita and Meloidogyne hapla. In this study, seven GH18 chitinases were identified and cloned from B. xylophilus based on genomic analyses. The deduced amino acid sequences of all these genes contained an N-terminal signal peptide and a GH18 catalytic domain. Phylogenetic analysis showed that the origin of B. xylophilus GH18 chitinases was independent of those from fungi and bacteria. Real-time quantitative reverse transcription PCR analysis indicated that GH18 chitinase genes had discrete expression patterns, representing almost all the life stages of B. xylophilus. In situ hybridisation showed that the mRNA of GH18 chitinase genes of B. xylophilus were detected mainly in the spermatheca, esophageal gland cells, seminal vesicle and eggs. RNA interference (RNAi) results revealed different roles of GH18 chitinase genes in B. xylophilus. Bx-chi-1, Bx-chi-2 and Bx-chi-7 were associated with reproduction, fungal cell-wall degradation and egg hatching, respectively. Bx-chi-5 and Bx-chi-6 may be involved in sperm metabolism. In conclusion, this study demonstrates that GH18 chitinases have multiple functions in the life cycle of B. xylophilus.
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, PR China.
authors.forename: Yuliang
authors.initials: Y
authors.lastname: Ju
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, PR China. Electronic address: xuanwang@njau.edu.cn.
authors.forename: Xuan
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, PR China.
authors.forename: Tinglong
authors.initials: T
authors.lastname: Guan
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, PR China.
authors.forename: Deliang
authors.initials: D
authors.lastname: Peng
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, PR China. Electronic address: lihm@njau.edu.cn.
authors.forename: Hongmei
authors.initials: H
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000201:enzymology; D002686:Chitin / Q000378:metabolism; D002688:Chitinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005658:Fungi / Q000201:enzymology; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D017403:In Situ Hybridization; D008018:Life Cycle Stages / Q000235:genetics; D016013:Likelihood Functions; D008297:Male; D010641:Phenotype; D010802:Phylogeny; D028223:Pinus / Q000469:parasitology; D010935:Plant Diseases / Q000469:parasitology; D021382:Protein Sorting Signals / Q000235:genetics; D034622:RNA Interference; D060888:Real-Time Polymerase Chain Reaction; D012098:Reproduction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017187:Tylenchida / Q000145:classification / Q000201:enzymology* / Q000382:microbiology / Q000502:physiology
chemical_list: D021382:Protein Sorting Signals; D002686:Chitin; D002688:Chitinases
keywords: Bursaphelenchus xylophilus; Developmental expression pattern; Gene silencing; Glycoside hydrolase family 18; In situ hybridisation