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6. Etioplasts are more susceptible to salinity stress than chloroplasts and photosynthetically active etio‐chloroplasts of wheat (Triticum aestivum L.).

Author

Ounoki, Roumaissa, Sóti, Adél, Ünnep, Renáta, Sipka, Gábor, Sárvári, Éva, Garab, Győző, and Solymosi, Katalin

Subjects
WHEAT, SMALL-angle neutron scattering, SALINITY, CHLOROPLASTS, SOIL salinity, GERMINATION, TRANSMISSION electron microscopy
Abstract

High soil salinity is a global problem in agriculture that directly affects seed germination and the development of the seedlings sown deep in the soil. To study how salinity affected plastid ultrastructure, leaf segments of 11‐day‐old light‐ and dark‐grown (etiolated) wheat (Triticum aestivum L. cv. Mv Béres) seedlings were floated on Hoagland solution, 600 mM KCl:NaCl (1:1) salt or isosmotic polyethylene glycol solution for 4 h in the dark. Light‐grown seedlings were also treated in the light. The same treatments were also performed on etio‐chloroplasts of etiolated seedlings greened for different time periods. Salt stress induced slight to strong changes in the relative chlorophyll content, photosynthetic activity, and organization of thylakoid complexes. Measurements of malondialdehyde contents and high‐temperature thermoluminescence indicated significantly increased oxidative stress and lipid peroxidation under salt treatment, except for light‐grown leaves treated in the dark. In chloroplasts of leaf segments treated in the light, slight shrinkage of grana (determined by transmission electron microscopy and small‐angle neutron scattering) was observed, while a swelling of the (pro)thylakoid lumen was observed in etioplasts. Salt‐induced swelling disappeared after the onset of photosynthesis after 4 h of greening. Osmotic stress caused no significant alterations in plastid structure and only mild changes in their activities, indicating that the swelling of the (pro)thylakoid lumen and the physiological effects of salinity are rather associated with the ionic component of salt stress. Our data indicate that etioplasts of dark‐germinated wheat seedlings are the most sensitive to salt stress, especially at the early stages of their greening. [ABSTRACT FROM AUTHOR]

Published
2023
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7. Iron uptake of etioplasts is independent from photosynthesis but applies the reduction-based strategy

Author

Sági-Kazár, Máté, Sárvári, Éva, Cseh, Barnabás, Illés, Levente, May, Zoltán, Hegedűs, Csaba, Barócsi, Attila, Lenk, Sándor, Solymosi, Katalin, Solti, Ádám, Sági-Kazár, Máté, Sárvári, Éva, Cseh, Barnabás, Illés, Levente, May, Zoltán, Hegedűs, Csaba, Barócsi, Attila, Lenk, Sándor, Solymosi, Katalin, and Solti, Ádám

Abstract

Introduction: Iron (Fe) is one of themost important cofactors in the photosynthetic apparatus, and its uptake by chloroplasts has also been associated with the operation of the photosynthetic electron transport chain during reduction-based plastidial Fe uptake. Therefore, plastidial Fe uptake was considered not to be operational in the absence of the photosynthetic activity. Nevertheless, Fe is also required for enzymatic functions unrelated to photosynthesis, highlighting the importance of Fe acquisition by non-photosynthetic plastids. Yet, it remains unclear how these plastids acquire Fe in the absence of photosynthetic function. Furthermore, plastids of etiolated tissues should already possess the ability to acquire Fe, since the biosynthesis of thylakoid membrane complexes requires a massive amount of readily available Fe. Thus, we aimed to investigate whether the reduction-based plastidial Fe uptake solely relies on the functioning photosynthetic apparatus. Methods: In our combined structure, iron content and transcript amount analysis studies, we used Savoy cabbage plant as a model, which develops natural etiolation in the inner leaves of the heads due to the shading of the outer leaf layers. Results: Foliar and plastidial Fe content of Savoy cabbage leaves decreased towards the inner leaf layers. The leaves of the innermost leaf layers proved to be etiolated, containing etioplasts that lacked the photosynthetic machinery and thus were photosynthetically inactive. However, we discovered that these etioplasts contained, and were able to take up, Fe. Although the relative transcript abundance of genes associated with plastidial Fe uptake and homeostasis decreased towards the inner leaf layers, both ferric chelate reductase FRO7 transcripts and activity were detected in the innermost leaf layer. Additionally, a significant NADP(H) pool and NAD(P)H dehydrogenase activity was detected in the etioplasts of the innermost leaf layer, indicating the presence of the red

Published
2023
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11. Reactivation of the Photosynthetic Apparatus of Resurrection Plant Haberlea rhodopensis during the Early Phase of Recovery from Drought- and Freezing-Induced Desiccation

Author

Mihailova, Gergana, primary, Christov, Nikolai K., additional, Sárvári, Éva, additional, Solti, Ádám, additional, Hembrom, Richard, additional, Solymosi, Katalin, additional, Keresztes, Áron, additional, Velitchkova, Maya, additional, Popova, Antoaneta V., additional, Simova-Stoilova, Lyudmila, additional, Todorovska, Elena, additional, and Georgieva, Katya, additional

Published
2022
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32. Leaf Growth and Photosynthetic Performance of Two Co-existing Oak Species in Contrasting Growing Seasons

Author

SZŐLLŐSI, Erzsébet, SÁRVÁRI, Éva, LÉVAI, László, MÉSZÁROS, Ilona, VERES, Szilvia, KANALAS, Péter, OLÁH, Viktor, and LAKATOS, Gyula

Subjects
photosynthesis, Természettudományok, oak, leaf growth, lcsh:SD1-669.5, drought, Biológiai tudományok, lcsh:Forestry, photochemical efficiency of PSII
Abstract

Ecophysiological investigations of Quercus petraea and Quercus cerris were performed atthe Sikfkút research site in the dry and humid growing seasons of 2003 and 2004. The resultssuggested that leaf growth and the photosynthetic apparatus of Q. petraea exhibited higher sensitivityto drought in 2003 than that of Q. cerris. In leaves of Q. petraea, chlorophyll content showed largerinter-annual and within-canopy variability than in those of Q. cerris. Fully developed leaves ofQ petraea showed lower SLM which indicated higher leaf cell wall elasticity allowing them tomaintain a water spending strategy, while high specific leaf mass (SLM) values reflected a watersaving strategy for Q. cerris. Water use efficiency of Q. cerris was higher than in the case ofQ. petraea, which may provide an advantage for this species in dry periods. In the contrasting yearsthe final leaf area and leaf mass of both species were determined by the amount of rainfall andtemperature conditions during the period of early exponential phase of leaf growth. As indicated bythe low values of the Fv/Fm chlorophyll fluorescence parameter the photosynthetic apparatus of bothspecies exhibited high susceptibility to abiotic stress factors in early spring. A large VAZ cycle poolindicated that zeaxanthin dependent heat dissipation was the main contributor to photoprotection ofphotosynthetic apparatus in young leaves but in fully developed leaves the relatively high lightsaturated ETR and low Pmax as well as the maintenance of high Fv/Fm even in severe dry periodsreflected the potential involvement of photorespiratory electron transport in photoprotection of bothspecies in summer. Drought in 2003 may have resulted in serious depletion of dry matter reservesinfluencing the vitality of trees in following year. Q. petraea showed lower photochemical activity inthe successive vegetation period after the dry year than Q. cerris which suggested lower tolerance todrought in the long term.

Published
2007

50. Preferential regeneration of the NADPH: protochlorophyllide oxidoreductase oligomer complexes in pea epicotyls after bleaching.

Author

Szenzenstein, Andrea, Kósa, Annamária, Solymosi, Katalin, Sárvári, Éva, and Böddi, Béla

Subjects
PEAS, OLIGOMERS, BLEACHING (Chemistry), POLYACRYLAMIDE, COLLOIDS, PROTOCHLOROPHYLLIDE, POLYMERS, PISUM
Abstract

The regeneration and stability of the NADPH:protochlorophyllide oxidoreductase (POR, EC 1.3.1.33) enzyme complexes were studied in bleached epicotyls of 9-day-old dark-germinated pea ( Pisum sativum L. cv. Zsuzsi) seedlings. Middle segments were illuminated with 1300 µmol m−2 s−1photon flux density (PFD) white light and subsequently incubated in total darkness for 4–24 h at 24°C. Almost the full amount of protochlorophyllide (Pchlide) was degraded after 60 min illumination. The preferential regeneration of the 655 nm emitting Pchlide form was observed after 4 h dark incubation; the accumulation of the short-wavelength Pchlide form—dominating in epicotyls of dark-grown seedling—required 18–24 h dark. The Pchlide content of bleached samples was around 2.5% of that of the etiolated samples; after 4 h of dark incubation this value increased to 4–7%. Polyacrylamide gel electrophoresis and western blot showed that the amount of the POR protein decreased to about 50% during bleaching; after 4 h regeneration it reached almost the same level as that of dark-grown samples. We concluded that much more POR protein compared with Pchlide pigment remained stable during bleaching and the non-destroyed POR units were able to form preferentially oligomers during the dark-regeneration which could collect de novo synthesized Pchlide into 655 nm emitting complexes. These data indicate the high stability of the POR protein in pea epicotyls and the importance of the molecular environment in stimulating the aggregation of POR units. [ABSTRACT FROM AUTHOR]

Published
2010
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