MicroRNAs and Their Cross-Talks in Plant Development

Plant development is a complex process influenced by exogenous and endogenous elements.A series of postembryonic developmental events is involved to form the final architecture and contend with the changing environment.MicroRNA（miRNA） is one of endogenous non-coding RNAs,which plays an important role in plant developmental regulation.In this review,we summarized 34 miRNA families that are closely associated with plant development.Among these families,nine are expressed only in specific organs,whereas 20 families are expressed in at least two different organs.It is known that some miRNAs are expressed across most processes of plant growth,while some appear only at particular developmental stages or under special environmental conditions such as drought,waterlogging and short-day time.These miRNAs execute their diverse functions by regulating developmental gene expression levels,interacting with phytohormone signaling response,participating in the biogenesis of ta-siRNAs and affecting the production of miRNAs.

Computational investigation of small RNAs in the establishment of root nodules and arbuscular mycorrhiza in leguminous plants

Many small RNAs have been confirmed to play important roles in the development of root nodules and arbuscular mycorrhiza. In this study, we carried out the identification of certain small RNAs in leguminous plants(Medicago truncatula, soybean, peanut and common bean), such as miRNAs, tRFs and srRNAs, as well as the computational investigation of their regulations. Thirty miRNAs were predicted to be involved in establishing root nodules and mycorrhiza, and 12 of them were novel in common bean and peanut. The generation of tRFs in M. truncatula was not associated with tRNA gene frequencies and codon usage. Six tRFs exhibited different expressions in mycorrhiza and root nodules. Moreover, srRNA^(5.8S) in M. truncatula was generated from the regions with relatively low conservation at the rRNA 3′ terminal. The protein-protein interactions between the proteins encoded by the target genes of miRNAs, tRFs and srRNAs were computed. The regulation of these three types of sRNAs in the symbiosis between leguminous plants and microorganisms is not a single regulation of certain signaling or metabolic pathways but a global regulation for the plants to own growth or specific events in symbiosis.