Do increases in xylem sap pH and/or ABA concentration mediate stomatal closure following nitrate deprivation?


Autoria(s): Dodd, IC; Tan, LP; He, J
Data(s)

01/01/2003

Resumo

Stomatal conductance (g(s)) of pepper (Capsicum annuum L.) plants decreased during the second photoperiod (day 2) after withholding nitrate (N). Stomatal closure of N-deprived plants was not associated with a decreased shoot water potential (Psi(shoot)); conversely Psi(shoot) was lower in N-supplied plants. N deprivation transiently (days 2 and 3) alkalized (0.2-0.3 pH units) xylem sap exuded from de-topped root systems under root pressure, and xylem sap expressed from excised shoots by pressurization. The ABA concentration of expressed sap increased 3-4-fold when measured on days 2 and 4. On day 2, leaves detached from N-deprived and N-supplied plants showed decreased transpiration rates when fed an alkaline (pH 7) artificial xylem (AX) solution, independent of the ABA concentration (10-100 nM) supplied. Thus changes in xylem sap composition following N deprivation can potentially close stomata. However, the lower transpiration rate of detached N-deprived leaves relative to N-supplied leaves shows that factors residing within N-deprived leaves also mediate stomatal closure, and that these factors assume greater importance as the duration of N deprivation increases.

Identificador

http://espace.library.uq.edu.au/view/UQ:64534

Idioma(s)

eng

Publicador

Oxford University Press

Palavras-Chave #Plant Sciences #Abscisic Acid #Capsicum #Nitrate #Stomata #Water Status #Xylem Ph #Abscisic-acid Content #Nitrogen Nutrition #Water Relations #Solanum-tuberosum #Sunflower Plants #Leaf Expansion #Pisum-sativum #Tomato Plants #Cotton Plants #Growth #C1 #270402 Plant Physiology #620208 Vegetables
Tipo

Journal Article