Rice Yellow Mottle Virusresistance by genome editing of theOryza sativaL. ssp. japonica nucleoporin geneOsCPR5.1but notOsCPR5.2

Abstract

SummaryRice yellow mottle virus (RYMV) causes one of the most devastating rice diseases in Africa. Management of RYMV is challenging. Genetic resistance provides the most effective and environment-friendly control. The recessive resistance locusrymv2(OsCPR5.1) had been identified in African rice (O. glaberrima), however, introgression intoO. sativa ssp. japonicaandindicaremains challenging due to crossing barriers. Here, we evaluated whether CRISPR/Cas9 genome editing of the two rice nucleoporin paralogsOsCPR5.1(RYMV2) andOsCPR5.2can be used to introduce RYMV resistance into thejaponicavariety Kitaake. Both paralogs had been shown to complement the defects of the Arabidopsisatcpr5mutant, indicating partial redundancy. Despite striking sequence and structural similarities between the two paralogs, only oscpr5.1loss-of-function mutants were fully resistant, while loss-of-functionoscpr5.2mutants remained susceptible, intimating thatOsCPR5.1plays a specific role in RYMV susceptibility. Notably, edited lines with short in-frame deletions or replacements in the N-terminal domain (predicted to be unstructured) ofOsCPR5.1were hypersusceptible to RYMV. In contrast to mutations in the single ArabidopsisAtCPR5gene, which caused severely dwarfed plants,oscpr5.1andoscpr5.2singleknockoutmutants show neither substantial growth defects nor symptoms indicative of programmed cell death, possibly reflecting functional redundancy of the isoforms regarding other important functions. The specific editing ofOsCPR5.1, while maintainingOsCPR5.2activity, provides a promising strategy for generating RYMV-resistance in eliteOryza sativalines as well as for effective stacking with other RYMV resistance genes or other traits.