title: Gα proteins Gvm2 and Gvm3 regulate vegetative growth, asexual development, and pathogenicityon apple in Valsa mali.
abstract: In fungi, heterotrimeric guanine-nucleotide binding proteins (G-proteins) are key elements of signal transduction pathways, which control growth, asexual and sexual development, as well as virulence. In this study, we have identified two genes encoding heterotrimeric G protein alpha subunits, named Gvm2 and Gvm3, from Valsa mali, the causal agent of apple Valsa canker. Characterization of Gvm2 and Gvm3 mutants indicates that Gvm3 may be a crucial regulator of vegetative growth. Deletion of the corresponding gene results in a 20% reduction in growth rate. Besides, Gvm2 and Gvm3 seem to be involved in asexual reproduction, and mutants are hypersensitive to oxidative and cell membrane stresses. Interestingly, both G protein alpha subunits were most probably involved in V. mali virulence. In infection assays using Malus domestica cv. 'Fuji' leaves and twigs, the size of lesions caused by deletion mutants △Gvm2, or △Gvm3 are significantly reduced. Furthermore, many genes encoding hydrolytic enzymes-important virulence factors in V. mali-are expressed at a lower level in these deletion mutants. Our results suggest that Gvm2 and Gvm3 play an important role in virulence probably by regulation of expression of cell wall degrading enzymes. △Gvm2, and △Gvm3 mutants were further analyzed with respect to their impact on the transcript levels of genes in the cAMP/PKA pathway. The expression of the genes encoding adenylate cyclase VmAC, protein kinase A (PKA) regulatory subunit VmPKR, and PKA catalytic subunit VmPKA1 are down-regulated in both mutants. Further analyses indicated that intracellular cAMP level and PKA activity are down-regulated in the △Gvm3 mutant, but are basically unchanged in the △Gvm2 mutant. Overall, our findings indicate that both Gvm2 and Gvm3 play diverse roles in the modulation of vegetative growth, asexual development, and virulence in V. mali.
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, People's Republic of China.
authors.forename: Na
authors.initials: N
authors.lastname: Song
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, People's Republic of China.
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Dai
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, People's Republic of China.
authors.forename: Baitao
authors.initials: B
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, People's Republic of China.
authors.forename: Yuxing
authors.initials: Y
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, People's Republic of China.
authors.forename: Ming
authors.initials: M
authors.lastname: Xu
authors.affiliation: Fachgebiet Phytopathologie, Institut für Phytomedizin, Universitӓt Hohenheim, Stuttgart, Germany.
authors.forename: Ralf Thomas
authors.initials: RT
authors.lastname: Voegele
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, People's Republic of China.
authors.forename: Xiaoning
authors.initials: X
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, People's Republic of China.
authors.forename: Zhensheng
authors.initials: Z
authors.lastname: Kang
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, People's Republic of China.
authors.forename: Lili
authors.initials: L
authors.lastname: Huang
mesh_terms: D001203:Ascomycota / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D044385:GTP-Binding Protein alpha Subunits / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D005816:Genetic Complementation Test; D027845:Malus / Q000382:microbiology* / Q000502:physiology*; D009154:Mutation; D010641:Phenotype; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology*; D012100:Reproduction, Asexual / Q000235:genetics; D013312:Stress, Physiological; D014774:Virulence / Q000235:genetics
chemical_list: D005656:Fungal Proteins; D044385:GTP-Binding Protein alpha Subunits; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases