Deciphering the Genetic Architecture of Plant Virus Resistance by GWAS, State of the Art and Potential Advances

Growing virus resistant varieties is a highly effective means to avoid yield loss due to infection by many types of virus. The challenge is to be able to detect resistance donors within plant species diversity and then quickly introduce alleles conferring resistance into elite genetic backgrounds. Until now, mainly monogenic forms of resistance with major effects have been introduced in crops. Polygenic resistance is harder to map and introduce in susceptible genetic backgrounds, but it is likely more durable. Genome wide association studies (GWAS) offer an opportunity to accelerate mapping of both monogenic and polygenic resistance, but have seldom been implemented and described in the plant–virus interaction context. Yet, all of the 48 plant–virus GWAS published so far have successfully mapped QTLs involved in plant virus resistance. In this review, we analyzed general and specific GWAS issues regarding plant virus resistance. We have identified and described several key steps throughout the GWAS pipeline, from diversity panel assembly to GWAS result analyses. Based on the 48 published articles, we analyzed the impact of each key step on the GWAS power and showcase several GWAS methods tailored to all types of viruses.

Engineering Resistance Against Viruses in Field Crops Using CRISPR-Cas9

: Various types biotic stresses affect growth and production of agricultural crops, among them viruses are of most concern which cause yield losses in all field crops; challenging global food security. Enhancement of host resistance against plant viruses is a priority for effective management of plant viral diseases. In the present context of climate change scenario, plant viruses are rapidly evolving and defeating the host resistance. Advances in genome editing techniques such as CRISPR-Cas9 [clustered regularly interspaced palindromic repeats-CRISPR-associated 9] have been recognized as a promising tool for the development of plant virus resistance. CRISPR-Cas9 genome editing tool is widely preferred due to high target specificity, simple, efficient, and reproducible genetic manipulation. CRISPR-Cas9 based virus resistance in plants has been successfully achieved through gene targeting and cleaving viral genome or altering the plant genome to enhance plant innate immunity. In this article, we have outlined the CRISPR-Cas9 system, plant immunity against viruses and use of CRISPR-Cas9 system to engineer virus resistance in plants. We also discuss prospects and challenges on the use of CRISPR-Cas9-mediated plant virus resistance in crop improvement.