Biological characterization of the melanin biosynthesis gene Bcscd1 in the plant pathogenic fungus Botrytis cinerea

Yingjun Zhou; Juanjuan Song; Yongchun Wang; Long Yang; Mingde Wu; Guoqing Li; Jing Zhang

doi:10.1016/j.fgb.2022.103693

Biological characterization of the melanin biosynthesis gene Bcscd1 in the plant pathogenic fungus Botrytis cinerea

Fungal Genet Biol. 2022 May:160:103693. doi: 10.1016/j.fgb.2022.103693. Epub 2022 Apr 6.

Authors

Yingjun Zhou¹, Juanjuan Song², Yongchun Wang², Long Yang², Mingde Wu², Guoqing Li², Jing Zhang³

Affiliations

¹ State Key Laboratory of Agricultural Microbiology and Key Laboratory of Plant Pathology of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China; Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410006, China.
² State Key Laboratory of Agricultural Microbiology and Key Laboratory of Plant Pathology of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China.
³ State Key Laboratory of Agricultural Microbiology and Key Laboratory of Plant Pathology of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China. Electronic address: zhangjing1007@mail.hzau.edu.cn.

PMID: 35398257
DOI: 10.1016/j.fgb.2022.103693

Abstract

The gray mold fungus Botrytis cinerea produces dark-colored conidia and sclerotia due to deposition of melanin on the cell wall of these structures. However, the role of melanin biosynthesis on development and function of conidia and sclerotia have not been well elucidated in this fungus. This study disrupted the melanin biosynthesis gene Bcscd1 (for scytalone dehydratase) in the wild type B05.10, and the resulting mutants were compared with B05.10 and complementary mutants (COM) for growth and development, virulence and response to biotic/abiotic stresses. Three disruption mutants were obtained, and they did not differ from B05.10 and COM in mycelial growth rate on potato dextrose agar, however, they formed brownish conidia and scleotia deficient in melanogenesis, whereas B05.10 and COM formed grayish conidia and black sclerotia with normal melanogenesis. The disruption mutants were as aggressive as B05.10 and COM in infection of tobacco leaves. TEM observation showed that the disruption mutant ΔScd1-85 formed numerous tiny grooves in the conidial cell wall, thereby causing uneven thickness in the cell wall. In contrast, B05.10 and COM rarely formed tiny grooves in their conidial cell wall with even thickness. Moreover, the sclerotial cortex cell wall of ΔScd1-85 lost rigidity and the cells became collapsed, whereas the sclerotial cortex cell wall of B05.10 and COM appeared rigid, and the cells appeared plump in shape. The disruption mutants were more sensitive than B05.10 and COM in response to chemical stresses (H₂O₂, NaCl, SDS, sorbitol) for conidial germination and sclerotial survival. The sclerotia of the disruption mutants were more susceptible than the sclerotia of B05.10 and COM to infection by the mycoparasite Trichoderma koningiopsis. These results confirmed previous studies about the effect of melanin production on pathogenicity of B. cinerea, and expanded our knowledge about the role of Bcscd1 in cell wall integrity and in response to biotic and abiotic stresses.

Keywords: Bcscd1; Biotic/abiotic stresses; Botrytis cinerea; Cell wall integrity; Melanin.

MeSH terms

Ascomycota*
Botrytis
Hydrogen Peroxide / metabolism
Melanins* / genetics
Plant Diseases / genetics
Plant Diseases / microbiology
Spores, Fungal / genetics

Substances

Melanins
Hydrogen Peroxide

Supplementary concepts

Botrytis cinerea