title: Novel Pectate Lyase Genes of Heterodera glycines Play Key Roles in the Early Stage of Parasitism.
abstract: Pectate lyases are known to play a key role in pectin degradation by catalyzing the random cleavage of internal polymer linkages (endo-pectinases). In this paper, four novel cDNAs, designated Hg-pel-3, Hg-pel-4, Hg-pel-6 and Hg-pel-7, that encode pectate lyases were cloned and characterized from the soybean cyst nematode, Heterodera glycines. The predicted protein sequences of HG-PEL-3, HG-PEL-4 and HG-PEL-6 differed significantly in both their amino acid sequences and their genomic structures from other pectate lyases of H. glycines (HG-PEL-1, HG-PEL-2 and HG-PEL-7). A phylogenetic study revealed that the pectate lyase proteins of H. glycines are clustered into distinct clades and have distinct numbers and positioning of introns, which suggests that the pectate lyase genes of H. glycines may have evolved from at least two ancestral genes. A Southern blot analysis revealed that multiple Hg-pel-6-like genes were present in the H. glycines genome. In situ hybridization showed that four novel pectate lyases (Hg-pel-3, Hg-pel-4, Hg-pel-6 and Hg-pel-7) were actively transcribed in the subventral esophageal gland cells. A semi-quantitative RT-PCR assay supported the finding that the expression of these genes was strong in the egg, pre-parasitic second-stage juvenile (J2) and early parasitic J2 stages and that it declined in further developmental stages of the nematode. This expression pattern suggests that these proteins play a role in the migratory phase of the nematode life cycle. Knocking down Hg-pel-6 using in vitro RNA interference resulted in a 46.9% reduction of the number of nematodes that invaded the plants and a 61.5% suppression of the development of H. glycines females within roots compared to the GFP-dsRNA control. Plant host-derived RNAi induced the silencing of the Hg-pel-6gene, which significantly reduced the nematode infection levels at 7 Days post inoculation (dpi). Similarly, this procedure reduced the number of female adults at 40 dpi, which suggests the important roles of this gene in the early stages of parasitism. Our combined data suggest that two types of pectate lyases are present in the H. glycines genome and may have different roles during infection.
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Huan
authors.initials: H
authors.lastname: Peng
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Jiangkuan
authors.initials: J
authors.lastname: Cui
authors.affiliation: Key Laboratory of Pests Comprehensive Governance for Tropical crops, Ministry of Agriculture, P. R. China, Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Science, Danzhou, China.
authors.forename: Haibo
authors.initials: H
authors.lastname: Long
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Wenkun
authors.initials: W
authors.lastname: Huang
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Lingan
authors.initials: L
authors.lastname: Kong
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Shiming
authors.initials: S
authors.lastname: Liu
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Wenting
authors.initials: W
authors.lastname: He
authors.affiliation: The National Engineering Research Center of Agri-biodiversity Applied Technologies, Yunnan Agricultural University, Kunming, China.
authors.forename: Xianqi
authors.initials: X
authors.lastname: Hu
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Deliang
authors.initials: D
authors.lastname: Peng
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005260:Female; D017238:Genes, Helminth; D015801:Helminth Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006790:Host-Parasite Interactions; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D010935:Plant Diseases / Q000469:parasitology*; D011133:Polysaccharide-Lyases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D016415:Sequence Alignment; D013025:Glycine max / Q000469:parasitology*; D017187:Tylenchida / Q000235:genetics / Q000502:physiology*
chemical_list: D015801:Helminth Proteins; D011133:Polysaccharide-Lyases; C023911:pectate lyase