RNAi-Based Biofungicides as a Promising Next-Generation Strategy for Controlling Devastating Gray Mold Diseases

Abstract

Botrytis cinerea is one of the most critical agro-economic phytopathogens and has been reported to cause gray mold disease in more than 1000 plant species. Meanwhile, small interfering RNA (siRNA), which induce RNA interference (RNAi), are involved in both host immunity and pathogen virulence. B. cinerea has been reported to use both siRNA effectors and host RNAi machinery to facilitate the progression of gray mold in host species. Accordingly, RNAi-based biofungicides that use double-stranded RNA (dsRNA) to target essential fungal genes are considered an emerging approach for controlling devastating gray mold diseases. Furthermore, spray-induced gene silencing (SIGS), in which the foliar application of dsRNA is used to silence the pathogen virulence genes, holds great potential as an alternative to host-induced gene silencing (HIGS). Recently, SIGS approaches have attracted research interest, owing to their ability to mitigate both pre-and post-harvest B. cinerea infections. The RNAi-mediated regulation of host immunity and susceptibility in B. cinerea-host interactions are summarized in this review, along with the limitations of the current knowledge of RNAi-based biofungicides, especially regarding SIGS approaches for controlling gray mold diseases under field conditions.

Trans-kingdom RNAs and their fates in recipient cells: advances, utilization, and perspectives

“…Because of laws and regulations concerning genetically modified organisms, crops that express dsRNA require approval from various regulatory agencies. These factors complicate broader applications of HIGS worldwide, although the practicality and efficiency of HIGS strategies are beyond question ( Liu et al., 2020b ; Islam and Sherif, 2020 ). In addition, a lack of commercial applications restricts the full potential of HIGS research.…”

“…Spraying crude extracts of bacteria expressing dsRNA has been used to protect plants against viruses ( Gan et al., 2010 ; Yin et al., 2010 ; Duan et al., 2012 ). Later, spray application of exogenous dsRNA or sRNA (spray-induced gene silencing [SIGS]) ( Koch et al., 2016 ) initiated an era of RNAi-based fungicide strategies for the control of crop disease ( Wang and Jin, 2017 ; Islam and Sherif, 2020 ). Compared with HIGS, SIGS avoids host genetic modification.…”

“…Because the HIGS approach is independent of resistant cultivars, HIGS technology is considered an ideal strategy for crop breeding ( Hua et al., 2018 ). Current applications of HIGS for crop protection against insects, fungi, nematodes, and mites, as well as the advantages and disadvantages of HIGS, have been summarized in detail ( Baulcombe, 2015 ; Weiberg and Jin, 2015 ; Wang et al., 2017a ; Wang and Jin, 2017 ; Hua et al., 2018 ; Zotti et al., 2018 ; Zhao and Guo, 2019 ; Zhu et al., 2019 ; Liu et al., 2020b ; Das and Sherif, 2020 ; Hou and Ma, 2020 ; Islam and Sherif, 2020 ).…”

Minicell‐based fungal RNAi delivery for sustainable crop protection

“…However, technical limitations of generating stable transformed plants and the growing public concerns surrounding the cultivation of genetically modified (GM) crops restrict the broad application of HIGS technology to a majority of horticultural crops. Recently, spray‐induced gene silencing (SIGS), which involves the exogenous application of dsRNAs and siRNAs has emerged as an appealing alternative to HIGS, as it does not incorporate foreign genes in the treated species and transgenerational inheritance of silencing constructs is unlikely (Wang et al ., 2017; Mcloughlin et al ., 2018a; Islam and Sherif, 2020). The exogenous application of dsRNA or siRNA to reduce B. fuckeliana infection has already been reported in many pathobiological systems (Wang et al ., 2016; Mcloughlin et al ., 2018b).…”

Silencing of the Slt2-Type MAP Kinase Bmp3 in Botrytis cinerea by Application of Exogenous dsRNA Affects Fungal Growth and Virulence on Lactuca sativa

“…The infection process of B. cinerea involves stages of conidial attachment, germination, host penetration, primary lesion formation, lesion expansion and tissue maceration followed by sporulation [12]. Gene knockout approaches allowed the identification of genes involved in the different stages of disease cycle [13] and among them there could be possible target for the development of RNAi-based fungicides [14].…”