PbWoxT1 mRNA from pear (Pyrus betulaefolia) undergoes long‐distance transport assisted by a polypyrimidine tract binding protein

Abstract

SummaryLittle is known about the mechanisms by which mRNAs are transported over long distances in the phloem between the rootstock and the scion in grafted woody plants.We identified an mRNA in the pear variety 'Du Li' (Pyrus betulaefolia) that was shown to be transportable in the phloem. It contains a WUSCHEL-RELATED HOMEOBOX (WOX) domain and was therefore named Wox Transport 1 (PbWoxT1).A 548-bp fragment of PbWoxT1 is critical in long-distance transport. PbWoxT1 is rich in CUCU polypyrimidine domains and its mRNAs interact with a polypyrimidine tract binding protein, PbPTB3. Furthermore, the expression of PbWoxT1 significantly increased in the stems of wild-type (WT) tobacco grafted onto the rootstocks of PbWoxT1 or PbPTB3 co-overexpressing lines, but this was not the case in WT plants grafted onto PbWoxT1 overexpressing rootstocks, suggesting that PbPTB3 mediates PbWoxT1 mRNA long-distance transport.We provide novel information that adds a new mechanism with which to explain the noncell-autonomous manner of WOX gene function, which enriches our understanding of how WOX genes work in fruit trees and other species.

Overexpression of the Prunus sogdiana NBS-LRR Subgroup Gene PsoRPM2 Promotes Resistance to the Root-Knot Nematode Meloidogyne incognita in Tobacco

“…To assay the expression level of PsoRPM2 in root of T1 tobaccos, qRT-PCR were used to test the root tips of T1 tobaccos 0, 1, 3, and 5 dpi with 2000 nematode J2s. Ntactin were used as reference gene and the qRT-PCR primers were consulted Duan et al (2016) . All statistical analyses and data summaries were obtained with the PASW Statistics 18 software.…”

Molecular Responses during Plant Grafting and Its Regulation by Auxins, Cytokinins, and Gibberellins

“…Another such protein, PbPTB3 in Pyrus betlaefolia is capable of transporting to long distances after binding with numerous mRNAs. This long-distance movement of mRNAs across the graft junction is favored by the binding of PbPTB3 to PbWoxT1 mRNA [47,48]. A cyclophilin protein SICyp1 (involved in the cell signaling pathway responsible for maintaining shoot to root ratio), which can move via phloem from the scion to the stock, favored by an enhancement in auxin response, and ultimately aid in promoting the growth of roots [49].…”

Plant grafting: how genetic exchange promotes vascular reconnection

“…Using grafting experiments, CmPP16 was shown to be transported with the mRNA from rootstock to scion (Xoconostle‐Cázares et al ., ). In a recent study, PbPTB3, a member of the PTB family of proteins in the pear variety ‘Du Li’ ( Pyrus betulaefolia ) that binds to numerous mRNAs, was shown to be transported long distances in the phloem and to bind the CUCU domain of PbWoxT1 mRNA (Duan et al ., ,b). The binding of PbPTB3 to PbWoxT1 mRNA promotes its long‐distance transport across the graft union.…”