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31. Protective effect of triacontanol against acidic mists in Samanea saman (Jacq.) Merrill seedlings: Differential responses in growth, 14CO2 fixation, ribulose-1,5-bisphosphate carboxylase, and electron transport activities

Creator:
Muthuchelian, K., Meenakshi, V., and Nedunchezhian, N.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
cow tamarind, donor side, electron transport, fresh and dry matter, leaf density and area, nitrate reductase, photosystems 1 and 2, and root and shoot length
Language:
Multiple languages
Description:
Seedlings of tropical leguminous tree Samanea saman (Jacq.) Merrill were exposed for 7 d to acidic mist (AM, induced by H2SO4) of pH 5.6, 4.0, and 2.0. AM significantly reduced seedling growth (root and shoot length, leaf density, leaf area, fresh and dry mass accumulation) and photosynthetic activities. In thylakoids isolated from leaves treated at pH 4.0 and 2.0 a decrease in the activities of photosystem (PS) 2 and whole chain electron transport was observed, but PS1 activity did not change. When the seedlings were subsequently sprayed with triacontanol (TRIA), the AM effect was partially or completely reversed indicating that TRIA can protect from AM effects. The artificial electron donors, di-phenylcarbazide (DPC) and hydroxylamine (NH2OH), markedly restored the loss of PS2 activity in AM (pH 2.0) treated leaves. This is the first report of alleviating the AM by TRIA in tropical tree seedlings. and K. Muthuchelian, V. Meenakshi, N. Nedunchezhian.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

32. Seasonal changes of selected parameters of CO2 fixation biochemistry of Norway spruce under the long-term impact of elevated CO2

Creator:
Urban, O. and Marek, M. V.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
acclimation depression, carbon sink, CO2 assimilation, elevated CO2 concentration, electron transport, Picea abies, and ribulose-1,5-bisphosphate carboxylase/oxygenase
Language:
Multiple languages
Description:
Twelve-year-old Norway spruce (Picea abies [L.] Karst.) trees were exposed to ambient (AC) or elevated (EC) [ambient + 350 µmol(CO2) mol-1] CO2 concentrations in open-top-chamber (OTC) experiment under the field conditions of a mountain stand. Short-term (4 weeks, beginning of the vegetation season) and long-term (4 growing seasons, end of the vegetation season) effects of this treatment on biochemical parameters of CO2 assimilation were evaluated. A combination of gas exchange, fluorescence of chlorophyll a, and application of a mathematical model of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) activity was used. The analysis showed that the depression of photosynthetic activity by long-term impact of elevated CO2 was mainly caused by decreased RuBPCO carboxylation rate. The electron transport rate as well as the rate of ribulose-1,5-bisphosphate (RuBP) formation were also modified. These modifications to photosynthetic assimilation depended on time during the growing season. Changes in the spring were caused mainly by local deficiency of nitrogen in the assimilating tissue. However, the strong depression of assimilation observed in the autumn months was the result of insufficient carbon sink capacity. and O. Urban, M. V. Marek.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

33. Senescence retarding effect of metal ions: Pigment and protein contents and photochemical activities of detached primary leaves of wheat

Creator:
Subhan, D. and Murthy, S. D. S.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
aluminium, carotenoids, chlorophyll, DCMU, electron transport, fluorescence, emission spectra, leaf senescence, magnesium, and potassium
Language:
Multiple languages
Description:
Al3+ significantly delayed the loss of chlorophyll (Chl), protein, and carotenoids when compared to K+ and Mg2+ during dark-induced senescence of detached primary leaves of Triticum aestivum. Thylakoid membranes isolated from Al3+ - treated leaves showed a better retention of photosystem (PS) 2, PS1, and whole chain electron transport activities than thylakoids of K+- or Mg2+-treated leaves. These ions protected the electron transport activities and restored the DCMU-dependent fluorescence increase of thylakoid membranes in a valency-dependent manner. Al3+ also delayed the change of excitation energy distribution during senescence. and D. Subhan, S. D. S. Murthy.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

34. Shade effect alters leaf pigments and photosynthetic responses in Norway spruce (Picea abies L.) grown under field conditions

Creator:
Bertamini, M., Muthuchelian, K., and Nedunchezhian, N.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence, diphenyl carbazide, donor side, electron transport, NH2OH, photosystems 1 and 2, polypeptides, and ribulose-1,5-bisphosphate carboxylase
Language:
Multiple languages
Description:
The contents of chlorophyll (Chl) and carotenoids (Car) per fresh mass were lower in shade needles than in sun needles. Ribulose-1,5-bisphosphate carboxylase (RuBPC) activity and contents of soluble proteins were also significantly lower in shade needles. In isolated thylakoids, a marked lower rate of whole chain and photosystem (PS) 2 activities were observed in shade needles. Smaller lower rate of PS1 activity was also observed in shade needles. The artificial exogenous electron donors, diphenyl carbazide (DPC) and NH2OH, significantly restored the loss of PS2 activity in shade needles. Similar results were obtained when Fv/Fm was evaluated by Chl fluorescence measurements. The marked lower rate of PS2 activity in shade needles was due to the lower contents of 47, 33, 28-25, 23, and 17 kDa polypeptides. This conclusion was confirmed by immunological studies showing that the content of the 33 kDa protein of the watersplitting complex was diminished significantly in shade needles. and M. Bertamini, K. Muthuchelian, N. Nedunchezhian.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

35. Short-term effects of surface dust: alleviating photoinhibition of cotton under high irradiance in the Tarim Basin

Creator:
Li, L. and Mu, G.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
chlorofyl, chlorophyll, chlorophyll a fluorescence, dust retention, electron transport, photosynthetic rate, 2, and 581
Language:
Multiple languages
Description:
Dust deposition on leaf surfaces can impact the growth and physiological traits of plants. We carried out a field experiment to investigate short-term effects of light surface dust on photosynthesis of cotton in the Tarim Basin using chlorophyll fluorescence and gas-exchange techniques. JIP-test analysis of OJIP curves showed that the total performance index for leaves without dust decreased by 32% at noon compared to the morning value. High irradiance at noon reduced actual quantum yield of PSII and increased nonphotochemical quenching for leaves without dust, showing photoinhibition. It suggested that light surface dust alleviated photoinhibition of cotton to high irradiance on a short-term basis. For the leaves without dust, high irradiance induced photoinhibition not only with respect to the photochemistry reactions but the biochemical pathways of CO2 fixation. Mechanisms such as thermal dissipation and enhanced electron flux to PSI protected the photosynthetic apparatus under high irradiance., L. Li, G. Mu., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

36. Synergistic effect of AlCl3 and kinetin on chlorophyll and protein contents and photochemical activities in detached wheat primary leaves during dark incubation

Creator:
Subhan, D. and Murthy, S. D. S.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
aluminium, chlorophyll a fluorescence, electron transport, leaf senescence, and photosystem
Language:
Multiple languages
Description:
Al3+ in combination with kinetin showed more protection against degradation of chlorophyll (Chl) and protein than Al3+ or kinetin alone during dark-induced senescence in wheat primary leaf segments. MV-dependent whole chain electron transport, photosystem (PS) 2 mediated oxygen evolution, and PS1 activities were also delayed to a greater extent. Absorbed excitation energy distribution was more in favour of PS1 in Al3+ plus kinetin-treated leaf thylakoids at 72 h. and D. Subhan, S. D. S. Murthy.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

37. Temperature and light dependence of photosynthetic activities in wheat seedlings grown in the presence of DCMU [3-(3,4-dichlorophenyl)-1,1-dimethylurea]

Creator:
Muthuchelian, K., Bertamini, M., and Nedunchezhian, N.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence, donor side, electron transport, photosystem, thylakoid membrane proteins, and Triticum
Language:
Multiple languages
Description:
Photosynthetic electron transfer was studied in thylakoids isolated from control and DCMU-grown wheat (Triticum aestivum L.) seedlings. When exposed to high temperature (HT) and high iradiance (HI), thylakoids showed large variations in the photosynthetic electron transport activities and thylakoid membrane proteins. A drastic reduction in the rate of whole electron transport chain (H2O → MV) was envisaged in control thylakoids when exposed to HT and HI. Such reduction was mainly due to the loss of photosystem 2, PS2 (H2O → DCBQ) activity. The thylakoids isolated from seedlings grown in the presence of DCMU showed greater resistance to HT and HI treatment. The artificial exogenous electron donors MnCl2, DPC, and NH2OH failed to restore the HI induced loss of PS2 activity in both control and DCMU thylakoids. In contrast, addition of DPC and NH2OH significantly restored the HT induced loss of PS2 activity in control thylakoids and partially in DCMU thylakoids. Similar results were obtained when Fv/Fm was evaluated by chlorophyll fluorescence measurements. The marked loss of PS2 activity in control thylakoids was evidently due to the loss of 33, 23, and 17 kDa extrinsic polypeptides and 28-25 kDa LHCP polypeptides. and K. Muthuchelian, M. Bertamini, N. Nedunchezhian.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

38. The cause of the difference in leaf net photosynthetic rate between two soybean cultivars

Creator:
Jiang, Hua and Xu, Da-Quan
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
carboxylation efficiency, chlorophyll fluorescence, electron transport, Glycine max, photochemical efficiency, photophosphorylation, photosystem 2, quantum yield, and ribulose-1,5-bisphosphate carboxylase
Language:
Multiple languages
Description:
To explore the cause of difference in photosynthetic performance between different cultivars of crops, leaf net photosynt rate (PN) and photosystem 2 (PS2) photochemical efficiency (Fv/Fm), apparent quantum yield of carbon assimilation (φc), electron transport rate, photophosphorylation activity, etc. were measured in two soybean cultivars, Heinong 42 and Heinong 37. At pod setting and filling, significant differences in PN between them were observed. The former with a higher PN (from 7 to 38 %) had a significantly higher leaf thickness, leaf dry mass/area (LMA), chlorophyll content, soluble protein content, apparent quantum yield of electron transport through PS2 (φe), carboxylation efficiency (CE), and ribulose-1,5-bisphosphate carboxylase (RuBPC) activity. The significantly higher PN of Heinong 42 is mainly due to its higher content and activity of RuBPC. and Hua Jiang, Da-Quan Xu.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

39. UV-B radiation induced alterations in the bioenergetic processes of photosynthesis

Creator:
Murthy, S.D.S. and Rajagompal, S.
Format:
print
Type:
model:internalpart and TEXT
Subject:
electron transport, fluorescence, ozone, and photosystems
Language:
Multiple languages
Description:
The review deals with the comprehensive analysis of ultraviolet-B (UV-B) induced alterations in photosynthetic processes of higher plants and possible protection mechanisms. Between two photosystems, photosystem 2 (PS2) is main target for UV- B radiation stress. Depending on the mode of treatment, the oxidising side of PS2 and reaction centres are mainly affected by UV-B treatment. As response to UV-B stress plants develop some inherent adaptive mechanisms which decide the extent of the overall damage.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public