The long-distance OPT3 movement is selective between herbaceous and woody plants as shown using Malus and Arabidopsis thaliana plants

Abstract

Long-distance mobile mRNAs play key roles in gene regulatory networks controlling plant development and stress resistance. However, the mechanisms underlying species-specific delivery of mRNA still need to be elucidated. Here, the use of grafts involving highly heterozygous apple (Malus) genotypes allowed us to demonstrate that MdOPT3 mRNA can be transported over a long distance, from the leaf to the root, to regulate Fe uptake; whereas, AtOPT3, the mRNA of the MdOPT3 homolog from Arabidopsis thaliana, does not move from shoot to root. Reciprocal heterologous expression of the two types of mRNAs showed that the immobile AtOPT3 moved from the shoot to the root in Malus and Populus plants, while the mobile MdOPT3 became immobile in A. thaliana and Solanum lycopersicum. Furthermore, we demonstrate that the different transmissibility of OPT3 in A. thaliana and Malus might be caused by the divergent RNA-binding proteins (RBPs) located in herbaceous and woody plants. This study provides insights into mechanisms underlying differences in mRNA mobility and validates the important physiological functions associated with this process.