Host-Induced Gene Silencing of a G Protein α Subunit Gene CsGpa1 Involved in Pathogen Appressoria Formation and Virulence Improves Tobacco Resistance to Ciboria shiraiana

Abstract

Hypertrophy sorosis scleroteniosis caused by Ciboria shiraiana is the most devastating disease of mulberry fruit. However, few mulberry lines show any resistance to C. shiraiana. An increasing amount of research has shown that host-induced gene silencing (HIGS) is an effective strategy for enhancing plant tolerance to pathogens by silencing genes required for their pathogenicity. In this study, two G protein α subunit genes, CsGPA1 and CsGPA2, were identified from C. shiraiana. Silencing CsGPA1 and CsGPA2 had no effect on hyphal growth but reduced the number of sclerotia and increased the single sclerotium weight. Moreover, silencing CsGpa1 resulted in increased fungal resistance to osmotic and oxidative stresses. Compared with wild-type and empty vector strains, the number of appressoria was clearly lower in CsGPA1-silenced strains. Importantly, infection assays revealed that the virulence of CsGPA1-silenced strains was significantly reduced, which was accompanied by formation of fewer appressoria and decreased expression of several cAMP/PKA- or mitogen-activated protein-kinase-related genes. Additionally, transgenic Nicotiana benthamiana expressing double-stranded RNA targeted to CsGpa1 through the HIGS method significantly improved resistance to C. shiraiana. Our results indicate that CsGpa1 is an important regulator in appressoria formation and the pathogenicity of C. shiraiana. CsGpa1 is an efficient target to improve tolerance to C. shiraiana using HIGS technology.

Appressoria—Small but Incredibly Powerful Structures in Plant–Pathogen Interactions

“…CsGPA1, a G protein α subunit gene, was identified and characterized by its roles in Ciboria shiraiana. The CsGPA1-silenced strains were significantly reduced in appressoria formation compared to the wild-type and empty vector strains [109].…”

Transcriptome Analysis Reveals the Function of a G-Protein α Subunit Gene in the Growth and Development of Pleurotus eryngii

“…Previous studies have shown that Gα subunits regulate the growth and development of fungal species [ 33 ]. The silence of two Gα subunit genes in Ciboria shiraiana , CsGPA1 and CsGPA2 , had no effect on mycelial growth, but they reduced the number of sclerotia and increased the weight of a single sclerotia [ 34 ]. In Aspergillus fumigatus , deletion of gpaB and ganA decreased colony growth, while growth was heightened in a gpaA deletion strain [ 35 ].…”

“…The silencing of CsGPA2 , the Gα subunit gene of C. shiraiana , resulted in a slight increase in peroxidase and laccase activities. However, the virulence of CsGPA1 silencing strain was reduced, but peroxidase and laccase activities were normal [ 34 ]. In this study, both overexpression and interfering strains significantly enhanced laccase activity compared to WT ( Figure 2 C).…”

Maleic acid and malonic acid reduced the pathogenicity of Sclerotinia sclerotiorum by inhibiting mycelial growth, sclerotia formation and virulence factors

“…Host-induced gene silencing (HIGS) enhances sclerotiorum, but it did decrease the quantity of sclerotia and increase the weight of individual sclerotia. Interestingly, only the strain with CsGPA1-silenced exhibited reduced virulence (Zhu et al 2021). Additionally, a study showed a positive correlation between sclerotinia virulence and colony diameter, but no correlation was found between virulence and the number, size, or weight of sclerotia.…”