1. The relationship between root hydraulics and scion vigour across Vitis rootstocks: what role do root aquaporins play?
- Author
-
Gambetta, G. A., Manuck, C. M., Drucker, S. T., Shaghasi, T., Fort, K., Matthews, M. A., Walker, M. A., and McElrone, A. J.
- Subjects
- *
PLANT roots , *ROOTSTOCKS , *AQUAPORINS , *VITIS vinifera , *SOILBORNE plant diseases , *EFFECT of stress on plants , *GRAPES - Abstract
Vitis vinifera scions are commonly grafted onto rootstocks of other grape species to influence scion vigour and provide resistance to soil-borne pests and abiotic stress; however, the mechanisms by which rootstocks affect scion physiology remain unknown. This study characterized the hydraulic physiology of Vitis rootstocks that vary in vigour classification by investigating aquaporin (VvPIP) gene expression, fine-root hydraulic conductivity (Lpr), % aquaporin contribution to Lpr, scion transpiration, and the size of root systems. Expression of several VvPIP genes was consistently greater in higher-vigour rootstocks under favourable growing conditions in a variety of media and in root tips compared to mature fine roots. Similar to VvPIP expression patterns, fine-root Lpr and % aquaporin contribution to Lpr determined under both osmotic (LprOsm) and hydrostatic (LprHyd) pressure gradients were consistently greater in high-vigour rootstocks. Interestingly, the % aquaporin contribution was nearly identical for LprOsm and LprHyd even though a hydrostatic gradient would induce a predominant flow across the apoplastic pathway. In common scion greenhouse experiments, leaf area-specific transpiration (E) and total leaf area increased with rootstock vigour and were positively correlated with fine-root Lpr. These results suggest that increased canopy water demands for scion grafted onto high-vigour rootstocks are matched by adjustments in root-system hydraulic conductivity through the combination of fine-root Lpr and increased root surface area. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF