Laboratory of Fruit Cell and Molecular Breeding, China Agricultural University, Beijing 100193, China.
Laboratory of Fruit Cell and Molecular Breeding, China Agricultural University, Beijing 100193, China.
Plant Sci. 2022 May;318:111232. doi: 10.1016/j.plantsci.2022.111232. Epub 2022 Feb 24.
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.
嫁接园艺作物会导致接穗材料的表型变化，这是由于大分子信号（包括 RNA 和蛋白质）在嫁接结合部的移动所致；然而，人们对转运核糖核蛋白（RNP）复合物的组成或这些大分子如何运输知之甚少。在这里，我们使用 PbPTB3-PbWoxT1 RNP 复合物的核心 PbPTB3 作为诱饵，从梨 cDNA 文库中筛选其相互作用伙伴。我们鉴定出一个锚蛋白 PbANK，它与 PbPTB3 相互作用，以促进其与 PbWoxT1 mRNA 一起通过韧皮部运输。异嫁接实验表明，在砧木中沉默 PbANK 会阻止 PbPTB3 和 PbWoxT1 mRNA 从砧木向接穗的运输。同样，异嫁接实验表明，PbANK 本身不能通过嫁接结合部长距离运输。荧光显微镜观察表明，沉默 ANK 会影响 PbPTB3 的细胞间扩散，并增加质膜通道处的胼胝质沉积。总的来说，这些发现表明，PbANK 通过降解胼胝质来增加细胞间运动的效率，从而介导 PbPTB3 和 PbWoxT1 的长距离运动。
