A TIR ‐ NLR gene from Arabidopsis Pla‐1 confers resistance to geminivirus infection

SUMMARY Geminiviruses are single‐stranded DNA viruses that infect many plant species and cause serious losses in agronomically important crops. An earlier study showed that the Arabidopsis thaliana ecotype Pla‐1 is resistant to infection by diverse geminivirus species and mapped the major resistance locus Geminivirus Resistance of Pla‐1 1 ( GRP1 ) to chromosome 1. In this study, we fine‐mapped the GRP1 locus to a 0.6‐Mb region and showed that its strength is gene‐dosage‐dependent. We also uncovered two minor resistance loci, GRP2 and GRP3 , that mapped to chromosomes 3 and 5, respectively, and showed that GRP3 resistance is dependent on GRP1 . RNA‐Seq analysis of plants inoculated with the geminivirus, cabbage leaf curl virus (CaLCuV, Begomovirus brassicae ), showed that AT1G31540, which is located in the GRP1 region and encodes a Toll/interleukin‐1 receptor (TIR) type nucleotide‐binding leucine‐rich repeat receptor (NLR), is upregulated in Pla‐1 compared to the susceptible Col‐0. AT1G31540 specifies two TIR‐NLR isoforms that contain non‐synonymous codon differences between the two Arabidopsis ecotypes. Expression of the longer Pla‐1 isoform, which includes a dual‐segment leucine‐rich repeat domain and an integrated domain at the C terminus, conferred CaLCuV resistance to Col‐0, resulting in reduced viral DNA accumulation and no leaf chlorosis. In contrast, expression of the shorter isoform, which lacks the second leucine‐rich repeat segment and the integrated domain, did not confer resistance. This study established that effector‐triggered, TIR‐NLR‐mediated plant innate immunity contributes to geminivirus defense responses and identified a new host genetic resource to combat these important plant viral pathogens.