SUN-Family Protein UvSUN1 Regulates the Development and Virulence of Ustilaginoidea virens

Abstract

Ustilaginoidea virens, the causal agent of rice false smut disease, is an important plant pathogen that causes severe quantitative and qualitative losses in rice worldwide. UvSUN1 is the only member of Group-I SUN family proteins in U. virens. In this work, the role of UvSUN1 in different aspects of the U. virens biology was studied by phenotypic analysis of Uvsun1 knockout strains. We identified that UvSUN1 was expressed during both conidial germination and the infection of rice. Disruption of the Uvsun1 gene affected the hyphal growth, conidiation, morphology of hyphae and conidia, adhesion and virulence. We also found that UvSUN1 is involved in the production of toxic compounds, which are able to inhibit elongation of the germinated seeds. Moreover, RNA-seq data showed that knockout of Uvsun1 resulted in misregulation of a subset of genes involved in signal recognition and transduction system, glycometabolism, cell wall integrity, and secondary metabolism. Collectively, this study reveals that Uvsun1 is required for growth, cell wall integrity and pathogenicity of U. virens, thereby providing new insights into the function of SUN family proteins in the growth and pathogenesis of this pathogen.

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

“…For virulence assay, strains were conducted on a susceptible rice cultivar LYP9 [ 27 ]. The virulence strains were tested according to the method described previously [ 28 ]. The mycelial plugs were placed into PS liquid cultures and shaken at 160 rpm for 7 d. Then, the cultures were homogenized in a blender.…”

“…The β-tubulin sequence or the rice Glyceraldehyde-3-Phosphate Dehydrogenase gene ( OsGAPDH ), respectively, was chosen as the endogenous reference for U. virens or rice [ 29 ]. The relative mRNA amounts were calculated by the −2 ΔΔCt method as described previously [ 28 ]. The PCR primers used in this study are listed in Table S1 .…”

Quantitative Loop-Mediated Isothermal Amplification Detection of Ustilaginoidea virens Causing Rice False Smut

“…It is widely accepted that Ustilaginoidea virens (teleomorph Villosiclava virens ) is the causal agent of rice false smut [ 14 , 15 ]. As a typical airborne disease, virulent pathogen spores land on the surface of a rice spikelet and germinate hyphae as well as false smut balls on the spikelet [ 3 , 12 , 16 , 17 , 18 ].…”

UvKmt2-Mediated H3K4 Trimethylation Is Required for Pathogenicity and Stress Response in Ustilaginoidea virens

“…During the rice booting stage, U. virens infects rice spikelets and fills floral organs and eventually forms false smut balls, which is the obvious and typical symptom of rice false smut disease [ 28 ]. The infection of U. virens blocks the nutrition transportation and normal development of grains, resulting in the increase in empty chaff rate and the decrease in grain weight [ 29 , 30 ]. In order to complete the infection, U. virens needs to coordinate acquiring nutrients from rice cells, eluding the plant’s immunity and adapting stresses from the host and the environment through different pathogenic mechanisms [ 31 , 32 , 33 , 34 , 35 , 36 ].…”