Limits...
Stomatal closure is induced by hydraulic signals and maintained by ABA in drought-stressed grapevine.

Tombesi S, Nardini A, Frioni T, Soccolini M, Zadra C, Farinelli D, Poni S, Palliotti A - Sci Rep (2015)

Bottom Line: Leaf gas exchange decreased progressively to zero during drought, and embolism-induced loss of hydraulic conductance in petioles peaked to ~50% in correspondence with strong daily limitation of stomatal conductance.Our data suggest that in grapevine stomatal conductance is primarily regulated by passive hydraulic mechanisms.Foliar ABA apparently limits leaf gas exchange over long-term, also preventing recovery of stomatal aperture upon rewatering, suggesting the occurrence of a mechanism of long-term down-regulation of transpiration to favor embolism repair and preserve water under conditions of fluctuating water availability and repeated drought events.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Scienze Agrarie, Alimentari e Ambientali, University of Perugia, Borgo 20 giugno 74, 06121 Perugia, Italy.

ABSTRACT
Water saving under drought stress is assured by stomatal closure driven by active (ABA-mediated) and/or passive (hydraulic-mediated) mechanisms. There is currently no comprehensive model nor any general consensus about the actual contribution and relative importance of each of the above factors in modulating stomatal closure in planta. In the present study, we assessed the contribution of passive (hydraulic) vs active (ABA mediated) mechanisms of stomatal closure in V. vinifera plants facing drought stress. Leaf gas exchange decreased progressively to zero during drought, and embolism-induced loss of hydraulic conductance in petioles peaked to ~50% in correspondence with strong daily limitation of stomatal conductance. Foliar ABA significantly increased only after complete stomatal closure had already occurred. Rewatering plants after complete stomatal closure and after foliar ABA reached maximum values did not induced stomatal re-opening, despite embolism recovery and water potential rise. Our data suggest that in grapevine stomatal conductance is primarily regulated by passive hydraulic mechanisms. Foliar ABA apparently limits leaf gas exchange over long-term, also preventing recovery of stomatal aperture upon rewatering, suggesting the occurrence of a mechanism of long-term down-regulation of transpiration to favor embolism repair and preserve water under conditions of fluctuating water availability and repeated drought events.

No MeSH data available.


Related in: MedlinePlus

Daily course of Ψstem, stomatal conductance, foliar ABA in day 2 (A,D,G), 8 (B,E,H) and 15 (C,F,I) in Montepulciano and Sangiovese vines.Each point is the mean of five vines ± SE. Points with asterisk are different per P < 0.05 (t-student test).
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f6: Daily course of Ψstem, stomatal conductance, foliar ABA in day 2 (A,D,G), 8 (B,E,H) and 15 (C,F,I) in Montepulciano and Sangiovese vines.Each point is the mean of five vines ± SE. Points with asterisk are different per P < 0.05 (t-student test).

Mentions: Diurnal course of Ψstem, gs and foliarABA progressively changed depending on water stress severity (Fig. 6). On day 2, Ψstem decreased from 4:00 am to 1:00 pm and remained approximately stable until 6:00 pm. During the same day, maximum gs was measured at 9:00 AM while a progressive decrease was observed during the rest of the day. Montepulciano displayed higher gs values than Sangiovese at all daytimes except at 6:00 pm. Foliar ABA was constant over the whole day and was slightly higher in Sangiovese than in Montepulciano, although this difference was statistically significant only at 4:00 am. On day 8, Ψstem decreased from −0.3 MPa and −0.5 MPa at pre-dawn (4:00 am), to −1.0 MPa and −1.2 MPa at 6:00 pm in Montepulciano and Sangiovese, respectively. Ψstem measured at 6:00 pm was slightly more negative than values measured at 1:00 pm. Montepulciano had Ψstem significantly higher than Sangiovese over the whole day. On day 8, gs was consistently lower than on day 2 and maximum gs measured at 9:00 am was below 0.1 mol m−2 s−1, while near-complete stomatal closure occurred at 1:00 pm and was maintained also at 6:00 pm. On the same day, foliar ABA was slightly higher than values recorded on day 2, although there was no difference between the measurements carried out at 4:00 am, 9:00 am and 1:00 pm on day 2 and day 8. On day 8, a consistent increase of foliar ABA was measured at 6:00 pm in both cultivars. On day 15, Ψstem decreased from −1.36 MPa and −1.58 MPa at pre-dawn (4:00 am) to −1.76 MPa and −1.8 MPa at 6:00 pm in Montepulciano and Sangiovese, respectively. In Montepulciano, Ψstem was consistently higher than in Sangiovese at any timing except for 6:00 pm. On the same date, gs was steadily close to zero in both cultivars. Foliar ABA further increased in both cultivars on day 15 compared to day 8. Although the difference was not statistically significant during the day except at midday, Sangiovese leaves had higher ABA than Montepulciano leaves on day 15.


Stomatal closure is induced by hydraulic signals and maintained by ABA in drought-stressed grapevine.

Tombesi S, Nardini A, Frioni T, Soccolini M, Zadra C, Farinelli D, Poni S, Palliotti A - Sci Rep (2015)

Daily course of Ψstem, stomatal conductance, foliar ABA in day 2 (A,D,G), 8 (B,E,H) and 15 (C,F,I) in Montepulciano and Sangiovese vines.Each point is the mean of five vines ± SE. Points with asterisk are different per P < 0.05 (t-student test).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4513549&req=5

f6: Daily course of Ψstem, stomatal conductance, foliar ABA in day 2 (A,D,G), 8 (B,E,H) and 15 (C,F,I) in Montepulciano and Sangiovese vines.Each point is the mean of five vines ± SE. Points with asterisk are different per P < 0.05 (t-student test).
Mentions: Diurnal course of Ψstem, gs and foliarABA progressively changed depending on water stress severity (Fig. 6). On day 2, Ψstem decreased from 4:00 am to 1:00 pm and remained approximately stable until 6:00 pm. During the same day, maximum gs was measured at 9:00 AM while a progressive decrease was observed during the rest of the day. Montepulciano displayed higher gs values than Sangiovese at all daytimes except at 6:00 pm. Foliar ABA was constant over the whole day and was slightly higher in Sangiovese than in Montepulciano, although this difference was statistically significant only at 4:00 am. On day 8, Ψstem decreased from −0.3 MPa and −0.5 MPa at pre-dawn (4:00 am), to −1.0 MPa and −1.2 MPa at 6:00 pm in Montepulciano and Sangiovese, respectively. Ψstem measured at 6:00 pm was slightly more negative than values measured at 1:00 pm. Montepulciano had Ψstem significantly higher than Sangiovese over the whole day. On day 8, gs was consistently lower than on day 2 and maximum gs measured at 9:00 am was below 0.1 mol m−2 s−1, while near-complete stomatal closure occurred at 1:00 pm and was maintained also at 6:00 pm. On the same day, foliar ABA was slightly higher than values recorded on day 2, although there was no difference between the measurements carried out at 4:00 am, 9:00 am and 1:00 pm on day 2 and day 8. On day 8, a consistent increase of foliar ABA was measured at 6:00 pm in both cultivars. On day 15, Ψstem decreased from −1.36 MPa and −1.58 MPa at pre-dawn (4:00 am) to −1.76 MPa and −1.8 MPa at 6:00 pm in Montepulciano and Sangiovese, respectively. In Montepulciano, Ψstem was consistently higher than in Sangiovese at any timing except for 6:00 pm. On the same date, gs was steadily close to zero in both cultivars. Foliar ABA further increased in both cultivars on day 15 compared to day 8. Although the difference was not statistically significant during the day except at midday, Sangiovese leaves had higher ABA than Montepulciano leaves on day 15.

Bottom Line: Leaf gas exchange decreased progressively to zero during drought, and embolism-induced loss of hydraulic conductance in petioles peaked to ~50% in correspondence with strong daily limitation of stomatal conductance.Our data suggest that in grapevine stomatal conductance is primarily regulated by passive hydraulic mechanisms.Foliar ABA apparently limits leaf gas exchange over long-term, also preventing recovery of stomatal aperture upon rewatering, suggesting the occurrence of a mechanism of long-term down-regulation of transpiration to favor embolism repair and preserve water under conditions of fluctuating water availability and repeated drought events.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Scienze Agrarie, Alimentari e Ambientali, University of Perugia, Borgo 20 giugno 74, 06121 Perugia, Italy.

ABSTRACT
Water saving under drought stress is assured by stomatal closure driven by active (ABA-mediated) and/or passive (hydraulic-mediated) mechanisms. There is currently no comprehensive model nor any general consensus about the actual contribution and relative importance of each of the above factors in modulating stomatal closure in planta. In the present study, we assessed the contribution of passive (hydraulic) vs active (ABA mediated) mechanisms of stomatal closure in V. vinifera plants facing drought stress. Leaf gas exchange decreased progressively to zero during drought, and embolism-induced loss of hydraulic conductance in petioles peaked to ~50% in correspondence with strong daily limitation of stomatal conductance. Foliar ABA significantly increased only after complete stomatal closure had already occurred. Rewatering plants after complete stomatal closure and after foliar ABA reached maximum values did not induced stomatal re-opening, despite embolism recovery and water potential rise. Our data suggest that in grapevine stomatal conductance is primarily regulated by passive hydraulic mechanisms. Foliar ABA apparently limits leaf gas exchange over long-term, also preventing recovery of stomatal aperture upon rewatering, suggesting the occurrence of a mechanism of long-term down-regulation of transpiration to favor embolism repair and preserve water under conditions of fluctuating water availability and repeated drought events.

No MeSH data available.


Related in: MedlinePlus