Laboratory of Fruit Cell and Molecular Breeding, China Agricultural University, Beijing 100193, China.
Int J Mol Sci. 2023 Apr 29;24(9):8051. doi: 10.3390/ijms24098051.
Grafting is widely used to improve the stress tolerance and the fruit yield of horticultural crops. Ribonucleoprotein complexes formed by mRNAs and proteins play critical roles in the communication between scions and stocks of grafted plants. In Pyrus betulaefolia, ankyrin was identified previously to promote the long-distance movement of the ribonucleoprotein complex(PbPTB3) by facilitating callose degradation at plasmodesmata. However, the mechanism of the ankyrin-mediated callose degradation remains elusive. In this study, we discovered a β-1,3-glucanase (EC 3.2.1.39, PbPDBG) using ankyrin as a bait from plasmodesmata by co-immunoprecipitation and mass spectrometry. Ankyrin was required for the plasmodesmata-localization of PbPDBG. The grafting and bombardment experiments indicated that overexpressing PbPDBG resulted in decreased callose content at plasmodesmata, and thereby promoting the long-distance transport of the ribonucleoprotein complex. Altogether, our findings revealed that PbPDBG was the key factor in ankyrin-mediated callose degradation at plasmodesmata.
嫁接被广泛用于提高园艺作物的抗逆性和果实产量。由 mRNA 和蛋白质形成的核糖核蛋白复合物在嫁接植物接穗和砧木之间的通讯中起着关键作用。在西洋梨中，先前已经鉴定出锚蛋白通过促进胞间连丝中胼胝质的降解来促进核糖核蛋白复合物（PbPTB3）的长距离移动。然而，锚蛋白介导的胼胝质降解的机制仍不清楚。在这项研究中，我们通过共免疫沉淀和质谱法发现了一种来自胞间连丝的β-1,3-葡聚糖酶（EC 3.2.1.39，PbPDBG），其以锚蛋白为诱饵。锚蛋白是 PbPDBG 在胞间连丝上定位所必需的。嫁接和轰击实验表明，过表达 PbPDBG 导致胞间连丝处的胼胝质含量降低，从而促进了核糖核蛋白复合物的长距离运输。总之，我们的研究结果表明，PbPDBG 是锚蛋白介导的胞间连丝胼胝质降解的关键因素。
