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Circadian regulation of leaf hydraulic conductance in sunflower ( Helianthus annuus L. cv Margot)
Author(s) -
NARDINI ANDREA,
SALLEO SEBASTIANO,
ANDRI SERGIO
Publication year - 2005
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2005.01320.x
Subject(s) - helianthus annuus , photoperiodism , sunflower , biology , botany , horticulture , circadian rhythm , hydraulic resistance , endocrinology , physics , mechanics
The circadian regulation of leaf hydraulic conductance ( K leaf ) was investigated in Helianthus annuus L. (sunflower). K leaf was measured with an high pressure flow meter during the light and dark period from plants growing at a photoperiod of 12 h. K leaf was 4.0 e−4 kg s −1 m −2 MPa −1 during the light period (LL) and 30–40% less during the dark period (DL). When photoperiod was inverted and leaves were measured for K leaf at their subjective light or dark periods, K leaf adjusted to the new conditions requiring 48 h for increasing from dark to light values and 4 d for the opposite transition. Plants put in continuous dark showed K leaf oscillating from light to dark values in phase with their subjective photoperiod indicating that K leaf changes were induced by the circadian clock. Several cuts through the minor veins reduced leaf hydraulic resistance ( R leaf ) of both LL and DL to the same value (1.0 e + 3 MPa m 2 s kg −1 ) that equalled the vascular resistance ( R v ). The contribution of the non‐vascular leaf resistance ( R nv ) to R leaf was of 71.9% in DL and of 58.4% in LL. The dominant R nv was shown to be reversibly modulated by mercurials, suggesting that aquaporins play a role in diurnal changes of K leaf .