Microarray profiling reveals microRNAs involving soybean resistance to Phytophthora sojae

MicroRNAs (miRNAs), a group of small noncoding RNAs, may serve as a class of post-transcriptional regulators in plant immune systems. Nevertheless, little is known about their roles in plant immune response to the oomycete pathogens. To identify miRNAs involved in the response of soybean to Phytophthora sojae, we examined expressional patterns of miRNAs upon infection by P sojae by microarray analysis in three soybean cultivars: Williams (susceptible), Conrad (quantitative resistance), and Williams 82 (qualitative resistance). Expression of a number of miRNAs was significantly altered upon infection and (or) in the different genotypes. qRT-PCR data with some miRNAs further confirmed the microarray results. Comparative analysis of the selected miRNAs and their targeted gene expression datasets uncovered many reciprocally expressed miRNA target pairs, which could proposed a feedback circuit between miRNA(s) and protein-coding genes. These results may serve as a basis for further in-depth studies of miRNAs involved in soybean resistance to P. sojae.