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1. Assessment of energy partitioning in PSII complexes using chlorophyll fluorescence: reviewing the different approaches toward the definition of a unified method

Creator:
Kornyeyev, D., Guadagno, C. R., and D’Ambrosio, N.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, photosynthesis, chlorophyll fluorescence, energy partitioning, photosystem II, 2, and 581
Language:
Multiple languages
Description:
Based on the examination and quantitative comparison of the approaches used to assess the energy partitioning in photosystem II, the unified method was proposed to calculate the contribution of the components of nonphotochemical quenching. and D. Kornyeyev, C. R. Guadagno, N. D’Ambrosio.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. Photosynthesis, energy partitioning, and metabolic adjustments of the endangered Cistaceae species Tuberaria major under high temperature and drought

Creator:
Osório, M. L., Osório, J., and Romano, A.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, anthocyanins, chlorophyll fluorescence imaging, energy partitioning, malondialdehyde, proline, soluble sugars, 2, and 58
Language:
Multiple languages
Description:
In view of predicted climatic changes for the Mediterranean region, study of high temperature and drought impacts on physiological responses of endangered species regains relevance. In this context, micropropagated plants of Tuberaria major, a critically endangered species, endemic of Algarve, were transferred to a controlled-environment cabinet with day/night temperatures set at 25/18°C (Reference) or 32/21°C (HT). After 15 days of HT acclimation, some plants were subjected to progressive drought followed by rewatering. The enhancement of temperature alone did not affect water relations and photosynthetic rates (PN) but the stomatal conductance (gs) exhibited a 3-fold increase in comparison with reference plants. The maximum quantum yield of photosystem (PS) II (Fv/Fm), the effective quantum yield of PSII photochemistry (ΦPSII), carotenoid (Car) and anthocyanin content enhanced, whereas the quantum yields of regulated (ΦNPQ) and nonregulated (ΦNO) energy dissipation decreased. Drought combined with HT reduced predawn leaf water potential to values of about -1.3 MPa, which had adverse effects on gas exchange and PSII activity. Values of PN and gs were 71 and 79% lower than those of HT plants. An impairment of photochemical activity was also observed: the decrease in ΦPSII and the increase of ΦNPQ. However, an irreversible photoinhibitory damage had not occurred. Carotenoid and anthocyanin content remained elevated and soluble sugars (SS) increased twice, whereas proline and MDA accumulation was not detected. On the first 24 h after water-stress relief, gs, PN, ΦPSII, and ΦNPQ did not recover, but SS returned to the reference level. Overall, T. major acquired an adequate capacity for a protection against the development of oxidative stress during drought and water recovery under HT. These findings suggest that T. major is prepared to deal with predicted climate changes., M. L. Osório, J. Osório, A. Romano., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. Photosynthetic response of lutein-deficient mutant lut2 of Arabidopsis thaliana to low temperature at high light

Creator:
Popova, A. V., Vladkova, R., Borisova, P., Georgieva, K., Mihailova, G., Velikova, V., Tsonev, T., and Ivanov, A. G.
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
abiotic stress, carotenoid mutant, energy partitioning, photoprotection, and photosynthetic performance
Language:
Multiple languages
Description:
Alterations in photosynthetic performance of lutein-deficient mutant lut2 and wild type (wt) of Arabidopsis thaliana were followed after treatment with low temperature and high light for 6 d. The obtained results indicated lower electrolyte leakage, lower excitation pressure, and higher actual photochemical efficiency of PSII in lut2 plants exposed to combined stress compared to wt plants. This implies that lut2 is less susceptible to the applied stress conditions. The observed lower values of quantum efficiency of nonphotochemical quenching and energy-dependent component of nonphotochemical quenching in lut2 suggest that nonphotochemical quenching mechanism(s) localized within LHCII could not be involved in the acquisition of higher stress tolerance of lut2 and alternatives to nonphotochemical quenching mechanisms are involved for dissipation of excess absorbed light. We suggest that the observed enhanced capacity for cyclic electron flow and the higher oxidation state of P700 (P700+), which suggests PSI-dependent energy quenching in lut2 plants may serve as efficient photoprotective mechanisms, thus explaining the lower susceptibility of lut2 to the combined stress treatments.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public