PbANK facilitates the long-distance movement of the PbWoxT1–PbPTB3 RNP complex by degrading deposited callose. (May 2022) - Wang, Shengyuan
Abstract: Grafting horticultural crops can result in phenotypic changes in the grafted materials due to the movement of macromolecular signals, including RNAs and proteins, across the graft union; however, little is known about the composition of trafficking ribonucleoprotein (RNP) complexes or how these macromolecules are transported. Here, we used the core of PbPTB3- PbWoxT1 RNP complex, PbPTB3, as bait to screen Pyrus betulaefolia cDNA library for its interaction partners. We identified an ankyrin protein, PbANK, that interacts with PbPTB3 to facilitate its transport through the phloem alongside PbWoxT1 mRNA. Heterografting experiments showed that silencing PbANK in rootstock prevented the transport of PbPTB3 and PbWoxT1 mRNA from the rootstock to the scion. Similarly, heterologous grafting experiments demonstrated that PbANK itself cannot be transported over long distances through a graft union. Fluorescence microscopy showed that silencing ANK affected the intercellular diffusion of PbPTB3 and increased callose deposition at plasmodesmata. Collectively, these findings demonstrate that PbANK mediates the long-distance movement of PbPTB3 and PbWoxT1 by degrading callose to increase the efficiency of cell-to-cell movement. Highlights: ● An ankyrin repeat protein (PbANK), interacts with PbPTB3 and PbWoxT1 formed RNP complex in Pyrus betulaefolia. ● PbANK facilitates the long-distance transmission of the PbPTB3-based RNP complex, although not mobile itself. ● PbANK degraded the callose deposition to increase the cell-to-cell movement efficiency of RNP complex.