Abstract

The ability for cut tissues to join and form a chimeric organism is a remarkable property of many plants; however, grafting is poorly characterized at the molecular level. To better understand this process, we monitored genome-wide gene expression changes in grafted Arabidopsis thaliana hypocotyls. We observed a sequential activation of genes associated with cambium, phloem, and xylem formation. Tissues above and below the graft rapidly developed an asymmetry such that many genes were more highly expressed on one side than on the other. This asymmetry correlated with sugar-responsive genes, and we observed an accumulation of starch above the graft junction. This accumulation decreased along with asymmetry once the sugar-transporting vascular tissues reconnected. Despite the initial starvation response below the graft, many genes associated with vascular formation were rapidly activated in grafted tissues but not in cut and separated tissues, indicating that a recognition mechanism was activated independently of functional vascular connections. Auxin, which is transported cell to cell, had a rapidly elevated response that was symmetric, suggesting that auxin was perceived by the root within hours of tissue attachment to activate the vascular regeneration process. A subset of genes was expressed only in grafted tissues, indicating that wound healing proceeded via different mechanisms depending on the presence or absence of adjoining tissues. Such a recognition process could have broader relevance for tissue events.

Keywords

plant grafting; regeneration; auxin; vascular tissue; wound healing

Published in

Proceedings of the National Academy of Sciences of the United States of America
2018, Volume: 115, number: 10, pages: E2447-E2456
Publisher: Proceedings of the National Academy of Sciences

SLU Authors

• Melnyk, Charles

  • Department of Plant Biology, Swedish University of Agricultural Sciences
    
  • University of Cambridge

UKÄ Subject classification

Developmental Biology


Publication identifier

DOI: https://doi.org/10.1073/pnas.1718263115

Permanent link to this page (URI)

https://res.slu.se/id/publ/94470