Plant grafting relieves asymmetry of jasmonic acid response induced by wounding between scion and rootstock in tomato hypocotyl.

Jiaqi Wang,Changjun Mu,Jingjing Chen,Heng Liu,Yuke He,Ni Chen,Kuide Yin,Dongliang Li,Yonggen Lou

doi:10.1371/journal.pone.0241317

Abstract

Plant grafting is a sequential wound healing process. However, whether wounding induces a different jasmonic acid (JA) response within half a day (12 h) after grafting or non-grafting remains unclear. Using the tomato hypocotyl grafting method, we show that grafting alleviates the asymmetrical accumulation of JA and jasmonic acid isoleucine conjugate (JA-Ile) in scion and rootstock caused by wounding, and from 2 h after tomato micrografting, grafting obviously restored the level of JA-Ile in the scion and rootstock. Meanwhile, five JA-related genes, SlLOX11, SlAOS, SlCOI1, SlLAPA and SlJA2L, are detected and show significant changes in transcriptional expression patterns within 12 h of grafting, from asymmetrical to symmetrical, when the expression of 30 JA- and defense-related genes were analyzed. The results indicated that grafting alleviates the asymmetrical JA and defense response between scion and rootstock of the tomato hypocotyl within 12 h as induced by wounding. Moreover, we demonstrate that in the very early hours after grafting, JA-related genes may be involved in a molecular mechanism that changes asymmetrical expression as induced by wounding between scion and rootstock, thereby promoting wound healing and grafting success.

Highlights

Plant grafting is an asexual propagation technique that is used to improve disease resistance, control vigor, increase yield and fruit quality, regulate precocity and plant size, and adapt to biotic and abiotic stress in horticulture [1]
To understand the dynamic accumulation of jasmonic acid (JA) at the first few hours after grafting, hypocotyl grafting of tomato was performed and the levels of JA and jasmonic acid isoleucine conjugate (JA-Ile) were measured at six time points (0, 0.5, 1, 2, 6, and 12 h) after grafting (Fig 1A)
Our results showed that in the separated parts, 2 of the 6 genes related to JA synthesis were asymmetric (Table 1), 2 of the 7 genes related to JA signaling were asymmetric (Table 2), 5 of the 6 genes related to defense were asymmetric (Table 3), and 3 of the 11 genes related to regulation were asymmetric (Table 4)

Summary

Introduction

Plant grafting is an asexual propagation technique that is used to improve disease resistance, control vigor, increase yield and fruit quality, regulate precocity and plant size, and adapt to biotic and abiotic stress in horticulture [1]. At the graft junction of Arabidopsis hypocotyls, tissues initially show asymmetry in cell division, cell differentiation, and gene expression, when the scion and rootstock tissue come into contact; this type of asymmetry will be relieved and the vascular connection start to form [8]. When tissues around the junction were isolated completely at different time points (6 h to 240 h) after grafting and using cut tissues that remained separated as control, the majority of genes were expressed asymmetrically at the scion and rootstocks. Wounding induces a JA response, and the accompanying wounding- associated asymmetry processes involved in the early hours (before 6 h) of grafting remain unclear. We propose that in the early hours after grafting, JA-related genes act as part of a mechanism that changes asymmetry that is induced by wounding, thereby promoting wound healing and grafting success

Results

Discussion

Materials and methods