Development of photosystem‐II activity during irradiance of etiolated <i>Helianthus</i> (Asteraceae) seedlings

Lebkuecher, Jefferson G.; Haldeman, Kurt A; Harris, Christine E.; Holz, Sonia L; Joudah, Sary A; Minton, Darcy A

doi:10.2307/2656970

Cited by 24 publications

(29 citation statements)

References 74 publications

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“…However, other physiological parameters indicated that chloroplasts were not completely mature. In particular, the maximum value for the F v /F m ratio (approximately 0.6) was lower than the one (0.83) determined for healthy and mature chloroplasts of green leaves (Björkman and Demmig, 1987), suggesting the presence of nonreducing Q B PSII complexes in the thylakoid membranes due to slow activation and/or slow development of the oxygen-evolving complex (Lebkuecher et al, 1999). Additionally, the chlorophyll a/b ratio was higher (approximately 3.8) than the same ratio (3.5) for mature chloroplasts of many higher plants.…”

Section: Functioning Of Chloroplasts In Acsccontrasting

confidence: 56%

Early Transcriptional Defense Responses in Arabidopsis Cell Suspension Culture under High-Light Conditions

et al. 2011

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The early transcriptional defense responses and reactive oxygen species (ROS) production in Arabidopsis (Arabidopsis thaliana) cell suspension culture (ACSC), containing functional chloroplasts, were examined at high light (HL). The transcriptional analysis revealed that most of the ROS markers identified among the 449 transcripts with significant differential expression were transcripts specifically up-regulated by singlet oxygen ( 1 O 2 ). On the contrary, minimal correlation was established with transcripts specifically up-regulated by superoxide radical or hydrogen peroxide. The transcriptional analysis was supported by fluorescence microscopy experiments. The incubation of ACSC with the 1 O 2 sensor green reagent and 2#,7#-dichlorofluorescein diacetate showed that the 30-min-HL-treated cultures emitted fluorescence that corresponded with the production of 1 O 2 but not of hydrogen peroxide. Furthermore, the in vivo photodamage of the D1 protein of photosystem II indicated that the photogeneration of 1 O 2 took place within the photosystem II reaction center. Functional enrichment analyses identified transcripts that are key components of the ROS signaling transduction pathway in plants as well as others encoding transcription factors that regulate both ROS scavenging and water deficit stress. A meta-analysis examining the transcriptional profiles of mutants and hormone treatments in Arabidopsis showed a high correlation between ACSC at HL and the fluorescent mutant family of Arabidopsis, a producer of 1 O 2 in plastids. Intriguingly, a high correlation was also observed with ABA deficient1 and more axillary growth4, two mutants with defects in the biosynthesis pathways of two key (apo)carotenoid-derived plant hormones (i.e. abscisic acid and strigolactones, respectively). ACSC has proven to be a valuable system for studying early transcriptional responses to HL stress.Oxygenic photosynthesis is the biological process that sustains life on Earth. In this light-driven reaction, water is split and molecular oxygen is released as a byproduct. The molecular oxygen that accumulates in the atmosphere is vital for aerobic organisms, but it can also become a precursor of (undesirable) reactive oxygen species (ROS) that can induce oxidative damage in cells and therefore place the life of aerobic organisms in jeopardy (Halliwell, 2006). In plants, ROS can be generated during photochemical energy conversion. High light (HL) is a stress factor responsible for direct inhibition of the photosynthetic electron transport chain in chloroplasts, leading to the generation of ROS in several locations: singlet oxygen () in PSI, and hydrogen peroxide (H 2 O 2 ) in the chloroplast stroma and also in peroxisomes through the photorespiratory cycle (Niyogi, 1999;Asada, 2006). Consequently, plants are obliged to cope with ROS generation in order to maintain plastid redox homeostasis. Together with the ROS detoxification pathways in chloroplasts, there are other active ROS fronts in organelles such as mitochondria and peroxisomes as we...

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Section: Functioning Of Chloroplasts In Acsccontrasting

confidence: 56%

Early Transcriptional Defense Responses in Arabidopsis Cell Suspension Culture under High-Light Conditions

et al. 2011

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“…Thus, we suppose that leaf area expansion process also involved the synthesis and assembly of photosynthetic apparatus in Jerusalem artichoke. So far, it is not definite whether primary photochemical reaction of PSII is the limiting step of photosynthetic capacity during the leaf growth, as contradictory results have been reported in different plants (Lebkuecher et al 1999;Srivastava et al 1999;Choinski et al 2003;Jiang et al 2005Jiang et al , 2006c. These contradictory results can be attributed to the inconsistent culture protocol or plant species.…”

Section: Discussionmentioning

confidence: 68%

Photosynthetic characterization of Jerusalem artichoke during leaf expansion

Chen

Shao

et al. 2011

Acta Physiol Plant

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Gas exchange, chlorophyll a fluorescence and modulated 820 nm reflection were investigated to explore the development of photosynthesis in Jerusalem artichoke (Helianthus tuberosus L.) leaves from initiation to full expansion. During leaf expansion, photosynthetic rate (Pn) increased and reached the maximal level when leaves were fully expanded. The same change pattern was also found in the stomatal conductance and chlorophyll content. Lower Pn could not be ascribed to the higher stomatal resistance in developing leaves, as intercellular CO 2 concentration was not significantly lower in these leaves. Lower Pn partly resulted from the lower actual photochemical efficiency of PSII in developing leaves, as more excited energy was dissipated through non-photochemical quenching. The development of primary photochemical reaction and electron transport in the donor side of PSII was completed in the initiating leaves. However, the development of electron transport in the acceptor side of PSII was not accomplished until leaves were fully expanded, indicated by the change in probability that an electron moves further than primary quinone (wo). PSI activity changed in parallel with wo suggesting that PSI cooperated well with PSII during leaf expansion. It should be stressed that the development of carbon fixation process was later than primary photochemical reaction but earlier than photosynthetic electron transport during leaf expansion. The later development of photosynthetic electron transport may reduce the production of reactive oxygen species from Mehler reaction, particularly under low carbon fixation.

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“…Photosystem 2 (PS2) is one of the major protein complexes in the photosynthetic apparatus in higher plants. As a result, more and more research effort has been devoted to understanding development of PS2 complex in the expanding leaves (Guenther and Melis 1990, Lebkuecher et al 1999, Srivastava et al 1999, Choinski et al 2003) and a lot of progress has been made in this field. Guenther and Melis (1990) found different developmental status of PS2 complex at various stages of chloroplast maturity.…”

Section: Introductionmentioning

confidence: 98%

“…More recently, Choinski et al (2003) noticed that the maximal quantum yield of PS2 (φ PS2 ) increases during leaf growth. Most previous investigations, however, were focused primarily on plants growing under artificial conditions with suboptimal irradiance levels (Guenther and Melis ---1990, Lebkuecher et al 1999, Srivastava et al 1999. The development of PS2 in leaves grown under field conditions has not been adequately investigated.…”

Section: Introductionmentioning

confidence: 99%

Enhanced photosystem 2 thermostability during leaf growth of Elm (Ulmus pumila) seedlings

Jiang¹,

Wang²,

Li³

et al. 2006

Photosynt.

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We examined photosynthetic activities and thermostability of photosystem 2 (PS2) in leaves of elm (Ulmus pumila) seedlings from initiation to full expansion. During leaf development, net photosynthetic rate (P N ) increased gradually and reached the maximum when leaves were fully developed. In parallel with the increase of P N , chlorophyll (Chl) content was significantly elevated. Chl a fluorescence measurements showed that the maximum quantum yield of PS2 (φ PS2 ), the efficiency a trapped exciton, moved an electron into the electron transport chain further than Q A -(Ψ o ), and the quantum yield of electron transport beyond Q A (φ Eo ) increased gradually. These results were independently confirmed by our low irradiance experiments. When subjected to progressive heat stress, the young leaves exhibited considerably lower φ PS2 and higher minimal fluorescence (F 0 ) than the mature leaves, revealing the highly sensitive nature of PS2 under heat in the newly initiating leaves. Further analysis showed that PS2 structure in the newly initiating leaves was strongly altered under heat, as evidenced by the increased fluorescence signals at the position of the K step. We therefore demonstrated an inhibition in the oxygen-evolving complex (OEC) in the young leaves. This resulted in decrease in amount of the functional PS2 reaction centres and relative increase in the PS2 reaction centres with inhibited electron transport at the acceptor side under heat. We suggest that the enhanced thermostability of PS2 during leaf development is associated with improved OEC stability.Additional key words: chlorophyll a fluorescence; JIP-test; leaf growth; thermostability of photosystem 2.

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Development of photosystem‐II activity during irradiance of etiolated Helianthus (Asteraceae) seedlings

Cited by 24 publications

References 74 publications

Early Transcriptional Defense Responses in Arabidopsis Cell Suspension Culture under High-Light Conditions

Early Transcriptional Defense Responses in Arabidopsis Cell Suspension Culture under High-Light Conditions

Photosynthetic characterization of Jerusalem artichoke during leaf expansion

Enhanced photosystem 2 thermostability during leaf growth of Elm (Ulmus pumila) seedlings

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