Over-Expression of LaMIR166a Promotes Organs Development in Nicotiana benthamiana

Abstract

Most studies related to the functions of miR165/166 have used Arabidopsis as the experimental material. However, Nicotiana benthamiana Domin is a more ideal research material as its typical stem structure. Additionally, most of the relevant research has focused on the functions of HD-ZIP III genes. As an upstream regulatory factor, the function of miR165/166 needs to be defined more directly. So far, the function of miR165/166 in N. benthamiana has not yet been examined. The Agrobacterium-mediated genetic transformation method was used to transform LaMIR166a from Larix leptolepis overexpression vector into N. benthamiana leaves, and three transgenic lines were obtained after molecular detection. Observation on the one-month seedlings revealed that overexpression of LaMIR166a markedly enhanced the biomass accumulation of N. benthamiana plants. Additionally, growth parameters including root length and basal diameter, lateral root density, stem ground diameter and stem internode length of transgenic plants were significantly higher than in wild type (WT) plants. Microscopic observation of stem slices and root squashes showed that overexpression of LaMIR166a significantly promoted xylem formation and development, and the growth of root hairs, which showed a bent phenotype. The results of the present study suggest that up-regulation of miR166a promotes the growth and development of N. benthamiana plants.