摘要：Non-coding small RNAs (sRNA) act as mediators of gene silencing and regulate plant growth, development and stress responses. Early insights into plant sRNAs established a role in antiviral defense and they are now extensively studied across plant–microbe interactions. Here, sRNA sequencing discovered a class of sRNA in rice (
Oryza sativa) specifically associated with foliar diseases caused by
Xanthomonas oryzae bacteria.
Xanthomonas-induced small RNAs (xisRNAs) loci were distinctively upregulated in response to diverse virulent strains at an early stage of infection producing a single duplex of 20–22 nt sRNAs. xisRNAs production was dependent on the Type III secretion system
, a major bacterial virulence factor for host colonization. xisRNA loci overlap with annotated transcripts sequences, with about half of them encoding protein kinase domain proteins. A number of the corresponding rice
cis-genes have documented functions in immune signaling and xisRNA loci predominantly coincide with the coding sequence of a conserved kinase motif. xisRNAs exhibit features of small interfering RNAs and their biosynthesis depend on canonical components
OsDCL1 and
OsHEN1. xisRNA induction possibly mediates post-transcriptional gene silencing but they do not broadly suppress
cis-genes expression on the basis of mRNA-seq data. Overall, our results identify a group of unusual sRNAs with a potential role in plant–microbe interactions.
