The cyclase-associated protein UvCap1 is required for mycelial growth and pathogenicity in the rice false smut fungus

Abstract

Rice false smut caused by Ustilaginoidea virens is one of the widespread rice diseases across the globe in recent years, however, we know little about its molecular mechanism of infection. The cAMP signaling pathway functions directly in the development and formation of infectious structures to regulate the infection process in many pathogenic fungi. In order to investigate the role of the cAMP signaling pathway in U. virens, UvCap1, a cyclase-associated-protein homologous to Saccharomyces cerevisiae Srv2 was identified. Three targeted deletion mutants of the UvCAP1 gene were obtained with gene replacement strategy assisted with CRISPR-Cas9 system. The UvCAP1 deletion mutants showed defects in mycelial growth and conidial production. Inoculation experiments demonstrated that ΔUvcap1 exhibited defects in pathogenicity. Compared with the wild-type strain, ΔUvcap1 showed decreased tolerance to sorbitol and H2O2, and increased tolerance to NaCl, CFW and SDS, and the intracellular cAMP level was significantly reduced in ΔUvcap1. Yeast two-hybrid assay identified the interactions of UvCap1 with UvAc1 (adenylase cyclase), two Ras proteins (UvRas1 and UvRas2) and UvSte50. Taken together, as a component of cAMP signaling pathway, UvCap1 plays important roles in the development and pathogenicity of U. virens.

Membrane Protein Bcest Is Involved in Hyphal Growth, Virulence and Stress Tolerance of Botrytis cinerea

“…However, under SDS-mediated stress, the growth rate of the ΔBcest mutant strain was higher than that of the WT strain B05.10, hence we speculate that the integrity of the cell membrane was destroyed after loss of Bcest, which in turn reduced the pressure of exogenous SDS on the cell membrane, allowing faster growth than the WT strain was capable of. This is consistent previous research (Cao et al 2021). In addition, the ability of the ΔBcest mutant strain to produce cellulases and proteases was signi cantly reduced, which is another important factor of pathogenicity (Hou.…”

The Ras GTPase‐activating protein UvGap1 orchestrates conidiogenesis and pathogenesis in the rice false smut fungus Ustilaginoidea virens

“…Target gene deletion mutant of UvGAP1 was generated using a gene replacement strategy assisted by the CRISPR‐Cas9 system as described previously (Cao et al., 2021 ). The gene replacement vector pMD19‐ UvGAP1 (Table S3 ) was constructed by insertion of the hygromycin gene ( HYG ) between the two flanking sequences (approximately 1.5 kb) of UvGAP1 .…”

“…Several signal transduction‐related genes involved throughout the development and infection processes have been characterized in U. virens . Adenylate cyclase (UvAc1), cyclase‐associated protein (UvCap1) and high‐affinity cAMP phosphodiesterase (UvPdeH) are conserved components of the cyclic‐AMP/protein kinase A (cAMP/PKA) signalling pathway with vital importance for mycelial growth, conidiation, pathogenicity, stress responses and regulation of the intracellular cAMP level of U. virens (Cao et al., 2021 ; Guo et al., 2019 ). Three MAP kinases, UvPmk1, UvHog1 and UvSlt2, have roles in conidiation, stress responses or pathogenicity in U. virens (Liang et al., 2018 ; Tang et al., 2020 ; Zheng et al., 2016 ).…”

The Velvet Protein UvVEA Regulates Conidiation and Chlamydospore Formation in Ustilaginoidea virens

“…Then, we generated gene deletion mutants by replacing the full-length fragment of the genes with a hygromycin resistance cassette using the CRISPR/Cas9 system ( Figures S3 and S4 ) [ 25 ]. For the complementation assays, a fragment containing an approximately 1.5 kb native promoter region and the full-length gene sequence were ligated into the pKO1 vector [ 26 ]. Agrobacterium tumefaciens strain AGL-1 harboring the pKO1- UvVEA or pKO1- UvVELB constructs were transformed into conidia of the Δ UvVEA or Δ UvVELB mutants, respectively, by Agrobacterium tumefaciens -mediated transformation [ 27 ].…”