Abstract
In viticulture, grafting is used to propagate Phylloxera-susceptible European grapevines, thereby using resistant American rootstocks. Although scion–rootstock reciprocal signaling is essential for the formation of a proper vascular union and for coordinated growth, our knowledge of graft partner interactions is very limited. In order to elucidate the scale and the content of scion–rootstock metabolic interactions, we profiled the metabolome of eleven graft combination in leaves, stems, and phloem exudate from both above and below the graft union 5–6 months after grafting. We compared the metabolome of scions vs. rootstocks of homografts vs. heterografts and investigated the reciprocal effect of the rootstock on the scion metabolome. This approach revealed that (1) grafting has a minor impact on the metabolome of grafted grapevines when tissues and genotypes were compared, (2) heterografting affects rootstocks more than scions, (3) the presence of a heterologous grafting partner increases defense-related compounds in both scion and rootstocks in shorter and longer distances from the graft, and (4) leaves were revealed as the best tissue to search for grafting-related metabolic markers. These results will provide a valuable metabolomics resource for scion–rootstock interaction studies and will facilitate future efforts on the identification of metabolic markers for important agronomic traits in grafted grapevines.
Highlights
The different metabolic profiles in the scion and rootstock tissues and phloem exudates of homografts and heterografts were analyzed for their significant reciprocal changes
To elucidate the metabolite content and the changes resulting from scion–rootstock interactions in nursery-grafted grapevines, we have profiled the metabolome of leaves, stems, and phloem exudate collected from above and below the graft union of 11 graft combinations five to six months after grafting
Results from the Principal component analyses (PCAs) (Figure S1), performed for each of the investigated sample type, indicate that grafting had a minor impact on the metabolome of grapevine when tissues or genotypes were compared
Summary
Grafting is an ancient well-established method for plant propagation and improvement. Its discovery likely arose from the attempts of the first agriculturalist for mimicking natural grafting, which allowed the domestication and diffusion of temperate fruit trees [1]. Since the use of grafting evolved from being merely a means of propagation towards its use to improve resilience against biotic and abiotic impacts [2] and has become a common method used in orchards and viticulture and in horticulture and ornamentals. A prominent example is found with grapevines and the spread of Phylloxera in Europe since the middle of the 19th century.
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