title: Polygalacturonase gene pgxB in Aspergillus niger is a virulence factor in apple fruit.
abstract: Aspergillus niger, a saprophytic fungus, is widely distributed in soil, air and cereals, and can cause postharvest diseases in fruit. Polygalacturonase (PG) is one of the main enzymes in fungal pathogens to degrade plant cell wall. To evaluate whether the deletion of an exo-polygalacturonase gene pgxB would influence fungal pathogenicity to fruit, pgxB gene was deleted in Aspergillus niger MA 70.15 (wild type) via homologous recombination. The ΔpgxB mutant showed similar growth behavior compared with the wild type. Pectin medium induced significant higher expression of all pectinase genes in both wild type and ΔpgxB in comparison to potato dextrose agar medium. However, the ΔpgxB mutant was less virulent on apple fruits as the necrosis diameter caused by ΔpgxB mutant was significantly smaller than that of wild type. Results of quantitive-PCR showed that, in the process of infection in apple fruit, gene expressions of polygalacturonase genes pgaI, pgaII, pgaA, pgaC, pgaD and pgaE were enhanced in ΔpgxB mutant in comparison to wild type. These results prove that, despite the increased gene expression of other polygalacturonase genes in ΔpgxB mutant, the lack of pgxB gene significantly reduced the virulence of A. niger on apple fruit, suggesting that pgxB plays an important role in the infection process on the apple fruit.
authors.affiliation: School of Food Science and Engineering, Hefei University of Technology, Hefei, China.
authors.forename: Cheng-Qian
authors.initials: CQ
authors.lastname: Liu
authors.affiliation: School of Food Science and Engineering, Hefei University of Technology, Hefei, China.
authors.forename: Kang-Di
authors.initials: KD
authors.lastname: Hu
authors.affiliation: School of Food Science and Engineering, Hefei University of Technology, Hefei, China.
authors.forename: Ting-Ting
authors.initials: TT
authors.lastname: Li
authors.affiliation: College of Environment and Energy Engineering, Anhui Jianzhu University, Hefei, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Xuzhou Institute of Agricultural Sciences of the Xuhuai District of Jiangsu Province, Xuzhou, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Yang
authors.affiliation: School of Food Science and Engineering, Hefei University of Technology, Hefei, China.|Anhui Siping Food Development Co. Ltd., Tongling, China.
authors.forename: Yan-Hong
authors.initials: YH
authors.lastname: Li
authors.affiliation: Anhui Siping Food Development Co. Ltd., Tongling, China.
authors.forename: He-Ping
authors.initials: HP
authors.lastname: Liu
authors.affiliation: School of Food Science and Engineering, Hefei University of Technology, Hefei, China.
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Chen
authors.affiliation: School of Food Science and Engineering, Hefei University of Technology, Hefei, China.
authors.forename: Hua
authors.identifier: http://orcid.org/0000-0002-8406-8373
authors.initials: H
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D001234:Aspergillus niger / Q000201:enzymology / Q000235:genetics* / Q000472:pathogenicity; D002473:Cell Wall / Q000382:microbiology; D005638:Fruit / Q000382:microbiology*; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D027845:Malus / Q000382:microbiology*; D011096:Polygalacturonase / Q000096:biosynthesis / Q000235:genetics*; D037521:Virulence Factors / Q000096:biosynthesis / Q000235:genetics
chemical_list: D037521:Virulence Factors; D011096:Polygalacturonase