Multiple Alleles Encoding Atypical NLRs with Unique Central Tandem Repeats in Rice Confer Resistance to Xanthomonas oryzae pv. oryzae

Plants have developed various mechanisms for avoiding pathogen invasion,including resistance(R)genes.Most R genes encode nucleotide-binding domain and leucine-rich repeat containing proteins(NLRs).Here,we report the isolation of three new bacterial blight R genes in rice,Xa1-2,Xa14,and Xa31(t),which were allelic to Xa1 and encoded atypical NLRs with unique central tandem repeats(CTRs).We also found that Xa31(t)was the same gene as Xa1-2.Although Xa1-2 and Xa14 conferred different resistance spectra,their performance could be attenuated by iTALEs,as has previously been reported for Xa1.XA1,XA1-2,XA14,and non-resistant RGAF differed mainly in the substructure of the leucine-rich repeat domain.They all contained unique CTRs and belonged to the CTR-NLRs,which existed only in Gramineae.We also found that interactions among these genes led to differing resistance performance.In conclusion,our results uncover a unique locus in rice consisting of at least three multiple alleles(Xa1,Xa1-2,and Xa14)that encode CTRNLRs and confer resistance to Xanthomonas oryzae pv.oryzae(Xoo).