Browsing by Author "Lee, Sangseok"
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- Gene expression and physiological responses associated to stomatal functioning in Rosa×hybrida grown at high relative air humidityPublication . Carvalho, Dália R.A.; Vasconcelos, Marta W.; Lee, Sangseok; Koning-Boucoiran, Carole F.S.; Vreugdenhil, Dick; Krens, Frans A.; Heuvelink, Ep; Carvalho, Susana M. P.tHigh relative air humidity (RH ≥ 85%) during growth disturbs stomatal functioning, resulting in excessivewater loss in conditions of high evaporative demand. We investigated the expression of nine abscisic acid(ABA)-related genes (involved in ABA biosynthesis, oxidation and conjugation) and two non-ABA relatedgenes (involved in the water stress response) aiming to better understand the mechanisms underlyingcontrasting stomatal functioning in plants grown at high RH. Four rose genotypes with contrasting sen-sitivity to high RH (one sensitive, one tolerant and two intermediate) were grown at moderate (62 ± 3%)or high (89 ± 4%) RH. The sensitive genotype grown at high RH showed a significantly higher stomatalconductance (gs) and water loss in response to closing stimuli as compared to the other genotypes. More-over, high RH reduced the leaf ABA concentration and its metabolites to a greater extent in the sensitivegenotype as compared to the tolerant one. The large majority of the studied genes had a relevant role onstomatal functioning (NCED1, UGT75B2, BG2, OST1, ABF3 and Rh-APX) while two others showed a minorcontribution (CYP707A3 and BG1) and AAO3, CYP707A1 and DREB1B did not contribute to the tolerancetrait. These results show that multiple genes form a highly complex regulatory network acting togethertowards the genotypic tolerance to high RH.
- Moderate salinity improves stomatal functioning in rose plants grown at high relative air humidityPublication . Carvalho, Dália R. A.; Vasconcelos, Marta W.; Lee, Sangseok; Vreugdenhil, Dick; Heuvelink, Ep; Carvalho, Susana M. P.Plants grown at high relative air humidity (RH ≥ 85%) show hampered stomatal closure in response to closing stimuli. We hypothesized that a moderate salinity during growth could trigger a stress response and stimulate stomatal functioning due to an increased leaf abscisic acid concentration ([ABA]). Cut rose ‘Prophyta’ was grown at moderate (63%) or high (89%) RH combined with three electrical conductivities (EC) in the nutrient solution (2, 4 and 6 dS m−1; adding NaCl). High RH resulted in higher pore area per leaf area in intact leaves, and higher stomatal conductance (gs) both in leaves subjected to desiccation and to light/dark transition, as compared to moderate RH. Increasing EC in high RH-grown plants lead to higher stomatal density but it enhanced stomatal closure in response to leaflet desiccation. This enhanced stomatal functioning was associated with increased [ABA] and [ABA + metabolites]. Nonetheless, plants grown at EC6 showed a significantly lower chlorophyll content, total plant dry weight and total leaf area. This negative effect on plant growth is related to ionic stress as the sodium and chloride concentrations increased in plants grown at EC6 compared to EC2 (up to 111- and 14-fold, respectively). This is the first study on the interactive effects of RH and salinity on stomatal functioning and anatomy during leaf development. It is shown that, when these two environmental factors that influence stomatal responsiveness in an opposite way are combined, moderate EC is able to improve stomatal responsiveness to leaflet desiccation in high RH-grown plants due to increased leaf [ABA].