The bZIP transcription factor UvbZIP6 mediates fungal growth, stress response, and false smut formation in Ustilaginoidea virens

Abstract

Rice false smut, caused by Ustilaginoidea virens, is one of the most destructive diseases in major world rice-producing regions. Basic leucine zipper (bZIP) proteins, which belong to an evolutionarily conserved transcription factor family and play critical roles in various biological processes in eukaryotes, have been previously identified in U. virens; however, their functions still need to be further elucidated. Therefore, we aimed to analyze the biological roles of UvbZIP6, a member of the bZIP family in U. virens. In this study, we found that UvbZIP6 was highly up-regulated at 7 days post-inoculation. Deletion of UvbZIP6 in U. virens resulted in an increase in fungal growth and sensitivity to Congo red and calcofluor white, whereas a decrease in sensitivity to hyperosmotic, oxidative, and sodium dodecyl sulfate stresses. Conidiation capacity was reduced in UvbZIP6-knockout mutants, but conidial morphology and germination were not affected. Although UvbZIP6-knockout mutants caused infection in rice plants, they could not form false smut balls. Our study indicates that UvbZIP6 is required for fungal growth, conidiation, stress response, and false smut ball formation of U. virens.

The histone deacetylase UvHOS2 regulates vegetative growth, conidiation, ustilaginoidin synthesis, and pathogenicity in Ustilaginoidea virens

“…Moreover, BLAST searches and homologous comparison revealed that some genes involved in conidial development (UV8b_06435, UV8b_04229, UV8b_04359, UV8b_04568, and UV8b_02287), cell wall integrity (UV8b_03905, UV8b_00692), and mycelial growth (UV8b_05833) were down-regulated (Additional file 2: Table S2). The genes related to the biosynthesis of secondary metabolites, including ustilaginoidin biosynthesis genes, cytochrome P450 genes, and non-ribosomal peptide synthetase genes, were also significantly down-regulated (Li et al 2019a;Liu et al 2022;Qu et al 2022). These data indicate that UvHos2 plays a crucial role in secondary metabolism in U. virens.…”

“…Inoculation assay was performed as described previously (Qu et al 2022). Briefly, U. virens conidial suspension, together with fragmented mycelia, was diluted to 2 × 10 6 conidia/mL and was then injection-inoculated into rice panicles of the variety Changbai15 at about 7 days before heading.…”

Pectate Lyase Genes Abundantly Expressed During the Infection Regulate Morphological Development of Colletotrichum camelliae and CcPEL16 Is Required for Full Virulence to Tea Plants

“…To investigate the biological functions of CcPELs in C. camelliae , it is necessary to generate targeted gene deletion mutants of the CcPEL s. The PEG-mediated protoplast transformation system has been widely used for genetic transformation in plant-pathogenic fungi ( 28 – 30 ). Thus, we attempted to establish a PEG-mediated protoplast transformation system for generating deletion mutants in C. camelliae .…”