title: Characterization of T-DNA insertion mutants with decreased virulence in the entomopathogenic fungus Beauveria bassiana JEF-007.
abstract: The bean bug, Riptortus pedestris, is a major agricultural pest that reduces crop quality and value. Chemical pesticides have contributed to pest management, but resistance to these chemicals has significantly limited their use. Alternative strategies with different modes of action, such as entomopathogenic fungi, are therefore of great interest. Herein, we explored how entomopathogenic fungi can potentially be used to control the bean bug and focused on identifying virulence-related genes. Beauveria bassiana (JEF isolates) were assayed against bean bugs under laboratory conditions. One isolate, JEF-007, showed >80 % virulence by both spray and contact exposure methods. Agrobacterium tumefaciens-mediated transformation (AtMT) of JEF-007 generated 249 random transformants, two of which (B1-06 and C1-49) showed significantly reduced virulence against Tenebrio molitor and R. pedestris immatures. Both species were used for rapid screening of virulence-reduced mutants. The two transformants had different morphologies, conidial production, and thermotolerance than the wild type. To determine the localization of the randomly inserted T-DNA, thermal asymmetric interlaced (TAIL) PCR was conducted and analysis of the two clones found multiple T-DNA insertions (two in B1-06 and three in C1-49). Genes encoding complex I intermediate-associated protein 30 (CIA30) and the autophagy protein (Atg22) were possibly disrupted by the T-DNA insertion and might be involved in the virulence. This work provides a strong platform for future functional genetic studies of bean bug-pathogenic B. bassiana. The genes putatively involved in fungal virulence should be experimentally validated by knockdown in future studies.
authors.affiliation: Department of Agricultural Biology, College of Agriculture and Life Sciences, Chonbuk National University, Jeonju, 561-756, South Korea.
authors.forename: Sihyeon
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Agricultural Biology, College of Agriculture and Life Sciences, Chonbuk National University, Jeonju, 561-756, South Korea.
authors.forename: Se Jin
authors.initials: SJ
authors.lastname: Lee
authors.affiliation: Department of Biotechnology and Animal Science, National Ilan University, Ilan, Taiwan.
authors.forename: Yu-Shin
authors.initials: YS
authors.lastname: Nai
authors.affiliation: Department of Agricultural Biology, College of Agriculture and Life Sciences, Chonbuk National University, Jeonju, 561-756, South Korea.
authors.forename: Jeong Seon
authors.initials: JS
authors.lastname: Yu
authors.affiliation: Department of Agricultural Biology, College of Agriculture and Life Sciences, Chonbuk National University, Jeonju, 561-756, South Korea.
authors.forename: Mi Rong
authors.initials: MR
authors.lastname: Lee
authors.affiliation: Department of Agricultural Biology, College of Agriculture and Life Sciences, Chonbuk National University, Jeonju, 561-756, South Korea.
authors.forename: Yi-Ting
authors.initials: YT
authors.lastname: Yang
authors.affiliation: Department of Agricultural Biology, College of Agriculture and Life Sciences, Chonbuk National University, Jeonju, 561-756, South Korea. jskim10@jbnu.ac.kr.
authors.forename: Jae Su
authors.initials: JS
authors.lastname: Kim
mesh_terms: D016960:Agrobacterium tumefaciens / Q000235:genetics; D000818:Animals; D052982:Beauveria / Q000235:genetics* / Q000472:pathogenicity*; D001681:Biological Assay / Q000379:methods; D004269:DNA, Bacterial / Q000235:genetics*; D020062:Heteroptera / Q000382:microbiology / Q000502:physiology*; D016254:Mutagenesis, Insertional; D016019:Survival Analysis; D013712:Tenebrio / Q000382:microbiology / Q000502:physiology; D014170:Transformation, Genetic; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D004269:DNA, Bacterial; C036483:T-DNA; D037521:Virulence Factors
keywords: Agrobacterium tumefaciens-mediated transformation; Beauveria bassiana; Riptortus pedestris; Thermal asymmetric interlaced PCR; Virulence