Host-induced gene silencing of fungal-specific genes of Ustilaginoidea virens confers effective resistance to rice false smut
Rice borer is one of the most important diseases in the world rice production, widely distributed in more than 40 rice growing countries in Asia, America, Africa and Europe. The disease is particularly serious in China, with an average annual area of about 45 million mu and a yield reduction of more than 150 million kilograms. It not only causes loss of rice production, but also produces toxins that are toxic and teratogenic to animal cells, posing a serious threat to human and animal health. The selection and breeding of disease-resistant varieties is the most economical and effective measure to mitigate the damage of rice strain disease, but at this stage there is no effective method to screen the source of resistance to rice strain disease, resulting in a relative lag in the identification of disease-resistant varieties, and there is still an extreme lack of high-quality rice strain disease resistant varieties and genetic resources.
HIGS technology takes the key genes of plant pathogenic bacteria growth and development and pathogenicity as molecular targets, and expresses RNA molecules complementary to the target genes of the pathogenic bacteria in the host plant, which are processed by plant cells to form siRNA; when the pathogenic bacteria infect the host plant, the siRNA is transferred to the pathogenic bacteria cells to specifically recognize the mRNA of the target genes of the pathogenic bacteria and induce the silencing of the target genes; thus affecting the normal growth and development and pathogenicity of the pathogenic bacteria. The researcher first investigated the development of the pathogenic gene in A. ramorum.
The researchers first identified a new septin gene, UvAspE, in Aspergillus oryzae, and found that UvAspE is involved in regulating mycelial growth, septum development and pathogenicity of Aspergillus oryzae by means of gene knockdown. To prevent the off-target effect of siRNA, the fungal-specific pathogenicity factors UvAspE, UvCom1 and UvPro1 were selected as RNAi target genes by comparative genomics approach in the genome of Inabaena.
Ricefalse smut (RFS) caused by Ustilaginoidea virens is one of the most importantdiseases in the majority of rice-growing areas worldwide. Rice false smutcauses not only yield loss, but also threatens human or animal health byproducing cyclopeptide mycotoxins. Cultivar resistance is the most economical,effective and environmentally friendly approach to control RFS. However,development of RFS-resistant rice cultivar still faces big challenges. In thefield, disease severity of RFS is largely affected by rice growth period andvariable weather conditions. To date, quite a few cultivars with stableresistance to RFS have been identified and could be used as resistant resourcefor disease-resistance breeding (Sun et al., 2020).
