3.3.3. *Sclerotinia* Resistance

*Sclerotinia sclerotioum* is a devastating fungal pathogen infecting more than 400 plant species across 75 families [137]. The typical symptoms caused by *Sclerotinia* pathogens include water-soaked rotting of leaves, stems, or fruit covered by fluffy fungal mycelium which subsequently develop compact resting bodies or sclerotia [115]. For over 15 years, its interaction with host plants has been investigated at the molecular level due to the complication of *S. sclerotiorum* possessing both biotrophic and necrotrophic lifestyles, which involves a variety biological processes including reactive oxygen species, lipid and calcium signaling, and DNA methylation-mediated transcription regulation [31]. This diverse interaction may be caused by a large set of candidate effector proteins, which can be identified through bioinformatic research [138]. Efforts in producing *Sclerotinia*-resistant canola varieties includes mutagenesis [139,140], breeding resistance [141,142], and genetic manipulation [143]. In 2011, a *Sclerotinia*-resistant *B. napus* variety was released by Pioneer Hi Bred International [144], however, there is limited information about quantitative disease resistance to the pathogen and associated QTL. By integrating QTL for the resistance, 26 candidate NBS-LRR genes in *B. napus* were found associated with *S. slerotiorum* resistance [145]. Through a transcriptome analysis approach, Chittem et al. [69] confirmed major pathways underlying communications between *S. sclerotiorum* and *B. napus* and the associated key genes. Based on knowledge on the plant immunity involvement of WRKY transcription factors in *Arabidopsis thaliana*, the roles of the corresponding WRKY genes in *B. napus*, *BnWRKY11*, and *BnWRKY70*, were elucidated using Cas9 enzymes and sgRNAs to induce nucleotide specific mutations in these genes, and the results showed the increased resistance to *S. sclerotiorum* in the mutant lines of *BnWRKY70*, while *Sclerotinia* susceptible phenotype was observed in lines with overexpressed *BnWRKY70* [71].
