RAS signalling genes can be used as host-induced gene silencing targets to control fungal diseases caused by Sclerotinia sclerotiorum and Botrytis cinerea

Recent advances in virulence of a broad host range plant pathogen Sclerotinia sclerotiorum: a mini-review

Sclerotinia sclerotiorum is a typical necrotrophic plant pathogenic fungus, which has a wide host range and can cause a variety of diseases, leading to serious loss of agricultural production around the world. It is difficult to control and completely eliminate the characteristics, chemical control methods is not ideal. Therefore, it is very important to know the pathogenic mechanism of S. sclerotiorum for improving host living environment, relieving agricultural pressure and promoting economic development. In this paper, the life cycle of S. sclerotiorum is introduced to understand the whole process of S. sclerotiorum infection. Through the analysis of the pathogenic mechanism, this paper summarized the reported content, mainly focused on the oxalic acid, cell wall degrading enzyme and effector protein in the process of infection and its mechanism. Besides, recent studies reported virulence-related genes in S. sclerotiorum have been summarized in the paper. According to analysis, those genes were related to the growth and development of the hypha and appressorium, the signaling and regulatory factors of S. sclerotiorum and so on, to further influence the ability to infect the host critically. The application of host-induced gene silencing (HIGS)is considered as a potential effective tool to control various fungi in crops, which provides an important reference for the study of pathogenesis and green control of S. sclerotiorum.

A MAP kinase cascade broadly regulates the lifestyle of Sclerotinia sclerotiorum and can be targeted by HIGS for disease control

Sclerotinia sclerotiorum causes white mold or stem rot in a wide range of economically important plants, bringing significant yield losses worldwide. Control of this pathogen is difficult as its resting structure sclerotia can survive in soil for years, and no Resistance genes have been identified in S. sclerotiorum hosts. Host-induced gene silencing (HIGS) has shown promising effects in controlling many fungal pathogens, including S. sclerotiorum. However, better molecular genetic understanding of signaling pathways involved in its development and pathogenicity is needed to provide effective HIGS gene targets. Here, by employing a forward genetic screen, we characterized an evolutionarily conserved mitogen-activated protein kinase (MAPK) cascade in S. sclerotiorum, consisting of SsSte50-SsSte11-SsSte7-Smk1, which controls mycelial growth, sclerotia development, compound appressoria formation, virulence, and hyphal fusion. Moreover, disruption of the putative downstream transcription factor SsSte12 led to normal sclerotia but deformed appressoria and attenuated host penetration, as well as impaired apothecia formation, suggestive of diverged regulation downstream of the MAPK cascade. Most importantly, targeting SsSte50 using host-expressed double-stranded RNA resulted in largely reduced virulence of S. sclerotiorum on both Nicotiana benthamiana leaves and transgenic Arabidopsis thaliana plants. Therefore, this MAPK signaling cascade is generally needed for its growth, development, and pathogenesis and can serve as ideal HIGS targets for mitigating economic damages caused by S. sclerotiorum infection.

The schizotrophic lifestyle of Sclerotinia sclerotiorum

Sclerotinia sclerotiorum is a cosmopolitan and typical necrotrophic phytopathogenic fungus that infects hundreds of plant species. Because no cultivars highly resistant to S. sclerotiorum are available, managing Sclerotinia disease caused by S. sclerotiorum is still challenging. However, recent studies have demonstrated that S. sclerotiorum has a beneficial effect and can live mutualistically as an endophyte in graminaceous plants, protecting the plants against major fungal diseases. An in-depth understanding of the schizotrophic lifestyle of S. sclerotiorum during interactions with plants under different environmental conditions will provide new strategies for controlling fungal disease. In this review, we summarize the pathogenesis mechanisms of S. sclerotiorum during its attack of host plants as a destructive pathogen and discuss its lifestyle as a beneficial endophytic fungus.