RNAs involved in the establishment of giant cells

Abstract

Plant response to bioagressors involves modifications of gene expression. Recently, microRNAs have been evidenced as crucial regulators of host gene expression during plants-pathogen interactions. Root-knot nematodes (RKN) are biotrophic plant parasitic worms that transform plant cells from root vascular cylinder into hypertrophied, multinucleate and highly metabolically active giant feeding cells. Since RKN are able to induce the formation of feeding cells in roots of almost all cultivated plants, they are thought to manipulate essential and conserved plant molecular pathways. Previous transcriptomic analyses evidenced that redifferentiation of root cells into giant feeding cells implies transcriptional reprogramming with a large repression of gene expression. Our study aims to investigate the role of microRNAs in the regulation of transcriptional repression observed during the redifferentiation into feeding cells. Small RNAs from Arabidopsis thaliana roots infected with the RKN model species Meloidogyne incognita were sequenced by SOLID technology. As a control, small RNAs from non infected roots were also sequenced. First, a catalog of microRNA expressed in healthy and infected roots was established. Then, microRNAs that are differentially expressed between healthy and infected roots were then identified by EdgeR statistical analyses. Preliminary results identified 24 microRNAs that are differentially expressed in infected roots and statistically relevant. Some of these microRNAs are known to be involved in plant responses to biotic and abiotic stress or in hormone-dependent process. Our results suggest that microRNAs are involved in the regulation of gene expression that results in redifferentiation of root cells into giant feeding cells.