Rootstock-scion signalling: Key factors mediating scion performance

Jan Henk Venema*, Francesco Giuffrida, Ivan Paponov, Alfonso Albacete, Francisco Pérez-Alfocea, Ian Dodd

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapterAcademicpeer-review

13 Citations (Scopus)
8 Downloads (Pure)

Abstract

Although the scion genotype often has a dominant effect on most agronomic traits, the rootstock introduces new sources of genotypic and phenotypic variability in the crop, due to rootstock×scion×environment interactions. These interactions are essentially based on hydraulic and chemical signals through the xylem (root to shoot) and the phloem (shoot to root). Although maximizing crop yield depends on the leaves receiving an optimal supply of water and mineral nutrients from the root system via the xylem, integrated plasticity involves long-distance communication, where small organic molecules play key roles. Except for some chlorophyll- and photosynthesis-related compounds, roots are believed to produce every type of compound that exists in plants (Gregory, 2006). Although many recent reviews have focused on specific chemical compounds in root-to-shoot communication, mainly phytohormones, other small molecules in xylem sap can modulate whole-plant processes and/or stress responses. Progress in identifying the roles of various signals in regulating root-to-shoot communication may be slow because at least four kinds of signals allow roots to influence shoots: (i) increased root export of an existing signalling compound or generating a new one; (ii) decreased root export of an existing signalling compound; (iii) accumulation of signal/message in the shoot (source) due to reduced demand in the root; and (iv) a reduction in signalling compounds in the shoot due to increased root demand. While this conceptual framework conveniently discriminates root-to-shoot (xylem sap composition: (i) and (ii)) and shoot-to-root (phloem sap composition: (iii) and (iv)), many signalling molecules can be synthesized in both root and shoot tissues and can travel in both xylem and phloem saps. This is recognized in empirical flow models, which have been applied to determine uptake, synthesis, transport and metabolism of signalling molecules. This chapter examines ionic, phytohormonal, proteomic and RNA signalling in planta, highlighting specific examples of signalling between the scion and rootstock. We draw attention to examples of grafting between specific combinations of scions and rootstocks that are deficient in (or overexpress) these signals, thus highlighting their importance (or otherwise) in regulating plant responses.
Original languageEnglish
Title of host publicationVegetable Grafting
Subtitle of host publicationPrinciples and Practices
EditorsGiuseppe Colla, Franscisco Pérez-Alfocea, Dietmar Schwarz
Place of PublicationWallingford, Oxfordshire, UK
PublisherCAB International
Chapter4
Pages94-131
Number of pages38
ISBN (Electronic)9781780648989
ISBN (Print)9781780648972
DOIs
Publication statusPublished - 1-Jan-2017

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