Abstract
Graft compatibility with at least most commercial cultivars is an essential trait in rootstock breeding programs for orchard performance and longevity. However, its range of application is restricted by physiological and biochemical factors that produce incompatible grafts. As a biological process, the incompatibility reaction is difficult to study because of the wide range of different scion-rootstock interactions produced when grafting. The aim of this study was to characterize the early cellular signs of graft incompatibility based mainly on histochemical tests and the quantification of cell-to-cell communication via plasmodesmata using a novel method termed in vitro 'stem unions'.Results from different Prunus graft combinations demonstrated that adhesion and callus proliferation occurred in both compatible and incompatible combinations 1 week after grafting. Nevertheless, the new cambium formation derived from the callus tissue appeared to be delayed in incompatible heterografts. A different cell wall composition as well as an enhanced metabolism was detected in the incompatible unions. Using fluorescence redistribution after photobleaching (FRAP) of a symplastic tracer, we determined the plasmodesmal coupling within the tissues primarily involved in the grafting processes. We found that the plasmodesmal coupling was higher between callus cells than between cortex cells. In addition, the plasmodesmal coupling was significantly higher within interfaces from compatible graft combinations compared with that of incompatible unions when analysed 2 weeks after grafting. These new findings strengthen the idea that callus cells are playing a central role in scion/rootstock interaction and that late rejection is predetermined already at the initial steps of union formation.
| Original language | English |
|---|---|
| Journal | Scientia Horticulturae |
| Volume | 143 |
| Pages (from-to) | 144-150 |
| Number of pages | 7 |
| ISSN | 0304-4238 |
| DOIs | |
| Publication status | Published - 16 Aug 2012 |