RT Journal Article
SR Electronic
T1 Root water gates and not changes in root structure provide new insights into plant physiological responses and adaptations to drought, flooding and salinity
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.10.27.357251
DO 10.1101/2020.10.27.357251
A1 Jean-Christophe Domec
A1 John S. King
A1 Mary J. Carmichael
A1 Anna Treado Overby
A1 Remi Wortemann R
A1 William K. Smith
A1 Guofang Miao
A1 Asko Noormets
A1 Daniel M. Johnson
YR 2020
UL http://biorxiv.org/content/early/2020/10/27/2020.10.27.357251.abstract
AB The influence of aquaporin (AQP) activity on plant water movement remains unclear, especially in plants subject to unfavorable conditions. We applied a multitiered approach at a range of plant scales to (i) characterize the resistances controlling water transport under drought, flooding and flooding plus salinity conditions; (ii) quantify the respective effects of AQP activity and xylem structure on root (Kroot), stem (Kstem) and leaf (Kleaf) conductances, and (iii) evaluate the impact of AQP-regulated transport capacity on gas exchange. We found that drought, flooding and flooding-salinity reduced Kroot and root AQP activity in Pinus taeda, whereas Kroot of the flood-tolerant Taxodium distichum did not decline under flooding. The extent of the AQP-control of transport efficiency varied among organs and species, ranging from 35%-55% in Kroot to 10%-30% in Kstem and Kleaf. In response to treatments, AQP-mediated inhibition of Kroot rather than changes in xylem acclimation controlled the fluctuations in Kroot. The reduction in stomatal conductance and its sensitivity to vapor pressure deficit were direct responses to decreased whole-plant conductance triggered by lower Kroot and larger resistance belowground. Our results provide new mechanistic and functional insights on plant hydraulics that are essential to quantifying the influences of future stress on ecosystem function.