Role of xanthophyll cycle-mediated photoprotection in Arbutus unedo plants exposed to water stress during the Mediterranean summer

Tobacco (Nicotiana tabacum L.) plantlets were grown on Murashige and Skoog medium in ventilated Magenta boxes and for the last subculture 10 μM ABA was added to the medium. After three weeks plantlets were transferred into pots with Perlite moistened with water and grown in controlled conditions (16-h photoperiod, day/night temperature 25/20 °C, air humidity about 45 %) either under low or high irradiance of 150 (LI) and 700 (HI) μmol m -2 s -1 , respectively. Content of endogenous ABA was 271.7 pmol g -1 (f.m.) in ABA treated plantlets, while in control plantlets it was only 53.3 pmol g -1 (f.m.). After ex vitro transfer, stomatal conductance and transpiration rate decreased considerably in comparison with in vitro grown plantlets and remained lower also 7 d after ex vitro transfer, especially in ABA-treated plants and so wilting of plants was practically eliminated. Net photosynthetic rate also decreased 1 d after ex vitro transfer but after 7 d it was mostly higher than that of in vitro grown plantlets. Water use efficiency significantly increased in ABA-treated plants. Chlorophyll a+b content did not change immediately after ex vitro transfer, nevertheless, after 7 d chlorophyll content was higher in ABA-treated plants. Pool of xanthophyll cycle pigments (XCP) and the degree of their deepoxidation (DEPS), which are connected with harmless dissipation of light energy, increased under high irradiance. Contents of XCP and ABA precursors (neoxanthin and violaxanthin) were lower in ABA-treated plants than in control plants indicating less stress in these plants. Most chlorophyll a fluorescence parameters did not change considerably after ex vitro transfer and so the photoinhibition was not observed even under HI. Slight increase in non-photochemical quenching under HI in ABA-treated plants suggested their better photoprotection. Thus application of ABA to the last subculture can improve acclimatization of in vitro grown plants to ex vitro conditions

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“…5). This ABA-induced increase in qNP under HI might be useful for photoprotection in agreement with the results of Baraldi et al (2008).…”

Section: Resultssupporting

confidence: 88%

Improvement of ex vitro transfer of tobacco plantlets by addition of abscisic acid to the last subculture

Pospíšilová¹,

Haisel²,

Synková³

et al. 2009

Biologia plant.

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“…Either way, it did not 278 persist at a high level as usually observed after a high solar illumination in conditions 279 of an additional stress, e.g. intensive drought (Baraldi et al, 2008). This suggests that 280 during our experiment the examined tree was not stressed by any other 281 environmental factor but high irradiance.…”

Section: Reflectance Measurements 149 150mentioning

confidence: 69%

Response of green reflectance continuum removal index to the xanthophyll de-epoxidation cycle in Norway spruce needles

Kováč

Malenovský

Urban

et al. 2013

Journal of Experimental Botany

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A dedicated field experiment was conducted to investigate the response of a green reflectance continuum removal-based optical index, called area under the curve normalized to maximal band depth between 511nm and 557nm (ANMB511-557), to light-induced transformations in xanthophyll cycle pigments of Norway spruce [Picea abies (L.) Karst] needles. The performance of ANMB511-557 was compared with the photochemical reflectance index (PRI) computed from the same leaf reflectance measurements. Needles of four crown whorls (fifth, eighth, 10th, and 15th counted from the top) were sampled from a 27-year-old spruce tree throughout a cloudy and a sunny day. Needle optical properties were measured together with the composition of the photosynthetic pigments to investigate their influence on both optical indices. Analyses of pigments showed that the needles of the examined whorls varied significantly in chlorophyll content and also in related pigment characteristics, such as the chlorophyll/carotenoid ratio. The investigation of the ANMB511-557 diurnal behaviour revealed that the index is able to follow the dynamic changes in the xanthophyll cycle independently of the actual content of foliar pigments. Nevertheless, ANMB511-557 lost the ability to predict the xanthophyll cycle behaviour during noon on the sunny day, when the needles were exposed to irradiance exceeding 1000 µmol m-2 s-1. Despite this, ANMB511-557 rendered a better performance for tracking xanthophyll cycle reactions than PRI. Although declining PRI values generally responded to excessive solar irradiance, they were not able to predict the actual de-epoxidation state in the needles examined. KeywordsChlorophyll to carotenoid ratio, continuum removal, excessive irradiance, leaf reflectance, spectral index, xanthophyll cycle pigments Analyses of pigments showed that the needles of the examined whorls varied 29 significantly in chlorophyll content and also in related pigment characteristics, e.g. 30 chlorophyll/carotenoids ratio. The investigation of the ANMB 511-557 diurnal behavior 31 revealed that the index is able to follow the dynamic changes in the xanthophyll 32 cycle independently of the actual content of foliar pigments. Nevertheless, ANMB 511-33 557 lost the xanthophyll cycle behavior predictability during noontime of the sunny 34 2 day, when the needles were exposed to irradiance exceeding 1000 µmol m -2 s -1 . 35

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“…4c) instead introduces two additional MD12-specific variables, namely the fraction of active PSII reaction centers (qLs) and the rate constant for sustained nonphotochemical quenching (kNPQs), resulting from the photoprotective retention of zeaxanthin even after dark-adaptation (Öquist & Huner, 2003). Both features have been observed to change over the season in response to cold (Gilmore & Ball, 2000;Porcar-Castell, 2011) and drought conditions (Baraldi et al, 2008), with important implications for SIF emission.…”

Section: Fluorescencementioning

confidence: 99%

Global sensitivity analysis of the SCOPE model: What drives simulated canopy-leaving sun-induced fluorescence?

Verrelst

Rivera

Tol

et al. 2015

Remote Sensing of Environment

233

185

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Role of xanthophyll cycle-mediated photoprotection in Arbutus unedo plants exposed to water stress during the Mediterranean summer

Cited by 23 publications

References 59 publications

Improvement of ex vitro transfer of tobacco plantlets by addition of abscisic acid to the last subculture

Improvement of ex vitro transfer of tobacco plantlets by addition of abscisic acid to the last subculture

Response of green reflectance continuum removal index to the xanthophyll de-epoxidation cycle in Norway spruce needles

Global sensitivity analysis of the SCOPE model: What drives simulated canopy-leaving sun-induced fluorescence?

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