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Sugar and hexokinase suppress expression of PIP aquaporins and reduce leaf hydraulics that preserves leaf water potential
Author(s) -
Kelly Gilor,
Sade Nir,
DoronFaigenboim Adi,
Lerner Stephen,
ShatilCohen Arava,
Yeselson Yelena,
Egbaria Aiman,
Kottapalli Jayaram,
Schaffer Arthur A.,
Moshelion Menachem,
Granot David
Publication year - 2017
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13568
Subject(s) - aquaporin , transpiration , stomatal conductance , xylem , water transport , sugar , biology , photosynthesis , arabidopsis , plant physiology , osmosis , microbiology and biotechnology , botany , mutant , biochemistry , gene , water flow , membrane , environmental engineering , engineering
Summary Sugars affect central aspects of plant physiology, including photosynthesis, stomatal behavior and the loss of water through the stomata. Yet, the potential effects of sugars on plant aquaporins ( AQP s) and water conductance have not been examined. We used database and transcriptional analyses, as well as cellular and whole‐plant functional techniques to examine the link between sugar‐related genes and AQP s. Database analyses revealed a high level of correlation between the expression of AQP s and that of sugar‐related genes, including the Arabidopsis hexokinases 1 ( At HXK 1 ). Increased expression of At HXK 1 , as well as the addition of its primary substrate, glucose (Glc), repressed the expression of 10 AQP s from the plasma membrane‐intrinsic proteins ( PIP ) subfamily ( PIP ‐ AQP s) and induced the expression of two stress‐related PIP ‐ AQP s. The osmotic water permeability of mesophyll protoplasts of At HXK 1 ‐expressing plants and the leaf hydraulic conductance of those plants were significantly reduced, in line with the decreased expression of PIP ‐ AQP s. Conversely, hxk1 mutants demonstrated a higher level of hydraulic conductance, with increased water potential in their leaves. In addition, the presence of Glc reduced leaf water potential, as compared with an osmotic control, indicating that Glc reduces the movement of water from the xylem into the mesophyll. The production of sugars entails a significant loss of water and these results suggest that sugars and At HXK 1 affect the expression of AQP genes and reduce leaf water conductance, to coordinate sugar levels with the loss of water through transpiration.