Differential tissue-specific expression of NtAQP1 in Arabidopsis thaliana reveals a role for this protein in stomatal and mesophyll conductance of CO₂ under standard and salt-stress conditions

Planta. 2014 Feb;239(2):357-66. doi: 10.1007/s00425-013-1988-8. Epub 2013 Oct 30.

Abstract

The regulation of plant hydraulic conductance and gas conductance involves a number of different morphological, physiological and molecular mechanisms working in harmony. At the molecular level, aquaporins play a key role in the transport of water, as well as CO₂, through cell membranes. Yet, their tissue-related function, which controls whole-plant gas exchange and water relations, is less understood. In this study, we examined the tissue-specific effects of the stress-induced tobacco Aquaporin1 (NtAQP1), which functions as both a water and CO₂ channel, on whole-plant behavior. In tobacco and tomato plants, constitutive overexpression of NtAQP1 increased net photosynthesis (A(N)), mesophyll CO₂ conductance (g(m)) and stomatal conductance (g(s)) and, under stress, increased root hydraulic conductivity (L(pr)) as well. Our results revealed that NtAQP1 that is specifically expressed in the mesophyll tissue plays an important role in increasing both A(N) and g(m). Moreover, targeting NtAQP1 expression to the cells of the vascular envelope significantly improved the plants' stress response. Surprisingly, NtAQP1 expression in the guard cells did not have a significant effect under any of the tested conditions. The tissue-specific involvement of NtAQP1 in hydraulic and gas conductance via the interaction between the vasculature and the stomata is discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aquaporin 1 / genetics*
  • Arabidopsis / cytology
  • Arabidopsis / genetics*
  • Arabidopsis / physiology
  • Carbon Dioxide / analysis
  • Carbon Dioxide / metabolism*
  • Chlorophyll / metabolism
  • Gene Expression Regulation, Plant*
  • Genes, Reporter
  • Mesophyll Cells / metabolism
  • Organ Specificity
  • Photosynthesis
  • Plant Epidermis / cytology
  • Plant Epidermis / genetics
  • Plant Epidermis / physiology
  • Plant Proteins / genetics
  • Plant Roots / cytology
  • Plant Roots / genetics
  • Plant Roots / physiology
  • Plant Stomata / cytology
  • Plant Stomata / genetics
  • Plant Stomata / physiology
  • Plant Transpiration / physiology*
  • Promoter Regions, Genetic / genetics
  • Sodium Chloride / metabolism
  • Tobacco / genetics*
  • Water / metabolism

Substances

  • Plant Proteins
  • Water
  • Chlorophyll
  • Carbon Dioxide
  • Aquaporin 1
  • Sodium Chloride