Location: Crops Pathology and Genetics ResearchTitle: Differential responses of grapevine rootstocks to water stress are associated with adjustments in fine root hydraulic physiology and suberization
|BARRIOS-MASIAS, FELIPE - University Of California|
|KNIPFER, THORSTEN - University Of California|
Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2015
Publication Date: 7/9/2015
Citation: Barrios-Masias, F.H., Knipfer, T., Mcelrone, A.J. 2015. Differential responses of grapevine rootstocks to water stress are associated with adjustments in fine root hydraulic physiology and suberization. Journal of Experimental Botany. doi: 10.1093/jxb/erv324.
Interpretive Summary: Drought resistance of commercially available grapevine rootstocks was associated with root traits that maintain high water uptake capacity under water stress, suggesting that roots that do not seal off can resupply the shoot with water more effectively once rewatering occurs compared to well suberized roots.
Technical Abstract: Water deficits are known to alter fine root structure and function, but little is known about how these responses contribute to differences in drought resistance across grapevine rootstocks. We studied how water deficit affects root anatomical and physiological characteristics in two grapevine rootstocks considered as low-medium (101-14Mgt) and highly (110R) drought resistant. Rootstocks were grown under prolonged and repeated drying cycles or frequent watering (‘dry’ and ‘wet’ treatments, respectively), and the following parameters were evaluated: root osmotic and hydrostatic hydraulic conductivity (Lpos and Lphyd, respectively), suberization, steady-state root pressure (Prs), sap exudation rates, sap osmotic potential, and exo- and endosmotic relaxation curves. For both rootstocks, the ‘dry’ treatment reduced fine root Lp, elicited earlier root suberization and higher sap osmotic potential, and generated greater Prs after rewatering, but the rootstocks responded differently under these conditions. Lpos, Lphyd and sap exudation rates were significantly higher in 110R than 101-14Mgt, regardless of moisture treatment. Under ‘dry’ conditions, 110R maintained a similar Lpos and decreased the Lphyd by 36% compared to ‘wet’ conditions, while both parameters were decreased by at least 50% for 101-14Mgt under ‘dry’ conditions. Interestingly, build-up of Prs in 110R was 34% lower on average than in 101-14Mgt suggesting differences in the development of suberized apoplastic barriers between the rootstocks as visualized by our analysis of suberization from fluorescence microscopy. Consistent with this pattern, 110R exhibited the greatest exosmotic Lpos (i.e., Lpos of water flowing from root to the soil) as determined from relaxation curves under wet conditions, where backflow may have limited its capacity to generate positive xylem pressure. The traits studied here can be used in combination to provide new insights needed for screening drought resistance across grapevine rootstocks.