splicing a single-stranded RNA precursor with a hairpin-loop structure.
miRNAs are involved in disease resistance-associated physiological pro-
cesses in plants by cleavaging their target genes in plants or pathogens.
For instance, miRNA393 could be induced by the
fl
agellin of bacterial
leaf spot pathogen in tomato, suppress the expression of growth hor-
mone receptor genes (
TIR1
,
AFB2
and
AFB3
), block the growth hormone
response pathways (
Navarro et al., 2006
), and inhibit the growth of bac-
terial pathogens in host plants. When a nontoxic strain of
Pseudomonas
syringae
pv.