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Photosystem I cyclic electron flow via chloroplast NADH dehydrogenase-like complex performs a physiological role for photosynthesis at low light.

Yamori W, Shikanai T, Makino A - Sci Rep (2015)

Bottom Line: Although substantial progress has been made in understanding the structure of the chloroplast NADH dehydrogenase-like (NDH) complex, which mediates one route of the cyclic electron transport pathways, its physiological function is not well understood.In contrast, here it is shown that impairment of NDH-dependent cyclic electron flow in rice specifically causes a reduction in the electron transport rate through PS I (ETR I) at low light intensity with a concomitant reduction in CO2 assimilation rate, plant biomass and importantly, grain production.There was no effect on PS II function at low or high light intensity.

View Article: PubMed Central - PubMed

Affiliation: Center for Environment, Health and Field Sciences, Chiba University, 6-2-1 Kashiwa-no-ha, Kashiwa, Chiba 277-0882, Japan.

ABSTRACT
Cyclic electron transport around photosystem I (PS I) was discovered more than a half-century ago and two pathways have been identified in angiosperms. Although substantial progress has been made in understanding the structure of the chloroplast NADH dehydrogenase-like (NDH) complex, which mediates one route of the cyclic electron transport pathways, its physiological function is not well understood. Most studies focused on the role of the NDH-dependent PS I cyclic electron transport in alleviation of oxidative damage in strong light. In contrast, here it is shown that impairment of NDH-dependent cyclic electron flow in rice specifically causes a reduction in the electron transport rate through PS I (ETR I) at low light intensity with a concomitant reduction in CO2 assimilation rate, plant biomass and importantly, grain production. There was no effect on PS II function at low or high light intensity. We propose a significant physiological function for the chloroplast NDH at low light intensities commonly experienced during the reproductive and ripening stages of rice cultivation that have adverse effects crop yield.

No MeSH data available.


Related in: MedlinePlus

Effect of the crr6 defect on in vivo photosynthesis at the different growth light conditions.Electron transport rate at photosystem I (A; ETR I), electron transport rate at photosystem II (B; ETR II), the ETR I/ETR II ratio (C), the fraction of PS II centers in the closed state (D; 1-qL) and non-photochemical quenching (E; NPQ), dark respiration rate (F; Rd), CO2 assimilation rate (G; A390), stomatal conductance (H; gs), intercellular CO2 concentration (I; Ci) at CO2 concentration of 390 μmol mol−1 at the respective growth light conditions were analyzed, as described in Materials & Methods. The light-intensity response curves of all these parameters are summarized in Fig. 3, S2 & S3. Data represent means ± SE, n = 4 ~ 6. Significant differences among the wild type plants, the control plants and the crr6 mutant are examined by Tukey-Kramer multiple comparison test (P < 0.05). When there is a significant difference only in the crr6 plants compared to the control plants and WT plants, * is indicated.
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f4: Effect of the crr6 defect on in vivo photosynthesis at the different growth light conditions.Electron transport rate at photosystem I (A; ETR I), electron transport rate at photosystem II (B; ETR II), the ETR I/ETR II ratio (C), the fraction of PS II centers in the closed state (D; 1-qL) and non-photochemical quenching (E; NPQ), dark respiration rate (F; Rd), CO2 assimilation rate (G; A390), stomatal conductance (H; gs), intercellular CO2 concentration (I; Ci) at CO2 concentration of 390 μmol mol−1 at the respective growth light conditions were analyzed, as described in Materials & Methods. The light-intensity response curves of all these parameters are summarized in Fig. 3, S2 & S3. Data represent means ± SE, n = 4 ~ 6. Significant differences among the wild type plants, the control plants and the crr6 mutant are examined by Tukey-Kramer multiple comparison test (P < 0.05). When there is a significant difference only in the crr6 plants compared to the control plants and WT plants, * is indicated.

Mentions: Figure 4 summarized several photosynthetic parameters at the same light intensity used for the plant growth. In WT plants, ETR I, ETR II and the ETR I/ETR II ratio at CO2 concentration of 390 μmol mol−1 were greater at high light intensity than those at low light intensity (Fig. 4). A390, stomatal conductance (gs) and dark respiration rate (Rd) were also greater at high light intensity than those at low light intensity (Fig. 4).


Photosystem I cyclic electron flow via chloroplast NADH dehydrogenase-like complex performs a physiological role for photosynthesis at low light.

Yamori W, Shikanai T, Makino A - Sci Rep (2015)

Effect of the crr6 defect on in vivo photosynthesis at the different growth light conditions.Electron transport rate at photosystem I (A; ETR I), electron transport rate at photosystem II (B; ETR II), the ETR I/ETR II ratio (C), the fraction of PS II centers in the closed state (D; 1-qL) and non-photochemical quenching (E; NPQ), dark respiration rate (F; Rd), CO2 assimilation rate (G; A390), stomatal conductance (H; gs), intercellular CO2 concentration (I; Ci) at CO2 concentration of 390 μmol mol−1 at the respective growth light conditions were analyzed, as described in Materials & Methods. The light-intensity response curves of all these parameters are summarized in Fig. 3, S2 & S3. Data represent means ± SE, n = 4 ~ 6. Significant differences among the wild type plants, the control plants and the crr6 mutant are examined by Tukey-Kramer multiple comparison test (P < 0.05). When there is a significant difference only in the crr6 plants compared to the control plants and WT plants, * is indicated.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4566099&req=5

f4: Effect of the crr6 defect on in vivo photosynthesis at the different growth light conditions.Electron transport rate at photosystem I (A; ETR I), electron transport rate at photosystem II (B; ETR II), the ETR I/ETR II ratio (C), the fraction of PS II centers in the closed state (D; 1-qL) and non-photochemical quenching (E; NPQ), dark respiration rate (F; Rd), CO2 assimilation rate (G; A390), stomatal conductance (H; gs), intercellular CO2 concentration (I; Ci) at CO2 concentration of 390 μmol mol−1 at the respective growth light conditions were analyzed, as described in Materials & Methods. The light-intensity response curves of all these parameters are summarized in Fig. 3, S2 & S3. Data represent means ± SE, n = 4 ~ 6. Significant differences among the wild type plants, the control plants and the crr6 mutant are examined by Tukey-Kramer multiple comparison test (P < 0.05). When there is a significant difference only in the crr6 plants compared to the control plants and WT plants, * is indicated.
Mentions: Figure 4 summarized several photosynthetic parameters at the same light intensity used for the plant growth. In WT plants, ETR I, ETR II and the ETR I/ETR II ratio at CO2 concentration of 390 μmol mol−1 were greater at high light intensity than those at low light intensity (Fig. 4). A390, stomatal conductance (gs) and dark respiration rate (Rd) were also greater at high light intensity than those at low light intensity (Fig. 4).

Bottom Line: Although substantial progress has been made in understanding the structure of the chloroplast NADH dehydrogenase-like (NDH) complex, which mediates one route of the cyclic electron transport pathways, its physiological function is not well understood.In contrast, here it is shown that impairment of NDH-dependent cyclic electron flow in rice specifically causes a reduction in the electron transport rate through PS I (ETR I) at low light intensity with a concomitant reduction in CO2 assimilation rate, plant biomass and importantly, grain production.There was no effect on PS II function at low or high light intensity.

View Article: PubMed Central - PubMed

Affiliation: Center for Environment, Health and Field Sciences, Chiba University, 6-2-1 Kashiwa-no-ha, Kashiwa, Chiba 277-0882, Japan.

ABSTRACT
Cyclic electron transport around photosystem I (PS I) was discovered more than a half-century ago and two pathways have been identified in angiosperms. Although substantial progress has been made in understanding the structure of the chloroplast NADH dehydrogenase-like (NDH) complex, which mediates one route of the cyclic electron transport pathways, its physiological function is not well understood. Most studies focused on the role of the NDH-dependent PS I cyclic electron transport in alleviation of oxidative damage in strong light. In contrast, here it is shown that impairment of NDH-dependent cyclic electron flow in rice specifically causes a reduction in the electron transport rate through PS I (ETR I) at low light intensity with a concomitant reduction in CO2 assimilation rate, plant biomass and importantly, grain production. There was no effect on PS II function at low or high light intensity. We propose a significant physiological function for the chloroplast NDH at low light intensities commonly experienced during the reproductive and ripening stages of rice cultivation that have adverse effects crop yield.

No MeSH data available.


Related in: MedlinePlus