Grafting with rootstocks induces extensive transcriptional re-programming in the shoot apical meristem of grapevine

Sarah Jane Cookson,Nathalie Ollat

doi:10.1186/1471-2229-13-147

Abstract

BackgroundGrafting is widely used in the agriculture of fruit-bearing crops; rootstocks are known to confer differences in scion biomass in addition to improving other traits of agricultural interest. However, little is known about the effect of rootstocks on scion gene expression. The objective of this study was to determine whether hetero-grafting the grapevine variety Vitis vinifera cv. 'Cabernet Sauvignon N’ with two different rootstocks alters gene expression in the shoot apex in comparison to the auto-grafted control. Cabernet Sauvignon was hetero-grafted with two commercial rootstock genotypes and auto-grafted with itself. Vigor was quantified by measurements of root, stem, leaf and trunk biomass. Gene expression profiling was done using a whole genome grapevine microarray; four pools of five shoot apex samples were harvested 4 months after grafting for each scion/rootstock combination.ResultsThe rootstocks increased stem biomass or conferred increased vigor by the end of the first growth cycle. Globally hetero-grafting two different genotypes together triggered an increase in shoot apex gene expression; however no genes were differentially expressed between the two hetero-grafts. The functional categories related to DNA, chromatin structure, histones, flavonoids and leucine rich repeat containing receptor kinases were the most enriched in the up-regulated genes in the shoot apex of hetero-grafted plants.ConclusionsThe choice of rootstock genotype had little effect on the gene expression in the shoot apex; this could suggest that auto- and hetero-grafting was the major factor regulating gene expression.

Highlights

Grafting is widely used in the agriculture of fruit-bearing crops; rootstocks are known to confer differences in scion biomass in addition to improving other traits of agricultural interest
Vigor is typically quantified by stem pruning weight at the end of the growing cycle and, in this work, conferred vigor was quantified by using measurements of dry stem biomass
Shoot apex samples were harvested four months after grafting when presumably the stress associated with grafting and the formation of a successful graft union has been overcome

Summary

Introduction

Grafting is widely used in the agriculture of fruit-bearing crops; rootstocks are known to confer differences in scion biomass in addition to improving other traits of agricultural interest. ‘Cabernet Sauvignon N’ with two different rootstocks alters gene expression in the shoot apex in comparison to the auto-grafted control. Rootstocks are known to alter various physiological processes in the scion such as vigor or biomass accumulation [4], fruit quality [5] and response to abiotic stresses (e.g. to water deficit [6] and salinity [7]). Commercial rootstocks used in viticulture have much smaller effects on scion vigor They are not associated with dwarfing phenotypes observed in fruit trees, but grapevine rootstocks are still important for fruit quality and yield. Vigor control mechanisms of different rootstocks are not necessarily the same for different scions, there is some degree of consistency with most commercial rootstock genotypes, being defined by viticulturists as high, moderate or low vigor e.g. [3]

Objectives

Methods

Results

Discussion

Conclusion