Coupling of cellular processes and their coordinated oscillations under continuous light in Cyanothece sp. ATCC 51142, a diazotrophic unicellular cyanobacterium
- Krishnakumar, Sujatha, Gaudana, Sandeep, Vinh, Nguyen, Viswanathan, Ganesh, Chetty, Madhu, Wangikar, Pramod
- Authors: Krishnakumar, Sujatha , Gaudana, Sandeep , Vinh, Nguyen , Viswanathan, Ganesh , Chetty, Madhu , Wangikar, Pramod
- Date: 2015
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 10, no. 5 (2015), p. 1-23
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- Description: Unicellular diazotrophic cyanobacteria such as Cyanothece sp. ATCC 51142 (henceforth Cyanothece), temporally separate the oxygen sensitive nitrogen fixation from oxygen evolving photosynthesis not only under diurnal cycles (LD) but also in continuous light (LL). However, recent reports demonstrate that the oscillations in LL occur with a shorter cycle time of ∼11 h. We find that indeed, majority of the genes oscillate in LL with this cycle time. Genes that are upregulated at a particular time of day under diurnal cycle also get upregulated at an equivalent metabolic phase under LL suggesting tight coupling of various cellular events with each other and with the cell's metabolic status. A number of metabolic processes get upregulated in a coordinated fashion during the respiratory phase under LL including glycogen degradation, glycolysis, oxidative pentose phosphate pathway, and tricarboxylic acid cycle. These precede nitrogen fixation apparently to ensure sufficient energy and anoxic environment needed for the nitrogenase enzyme. Photosynthetic phase sees upregulation of photosystem II, carbonate transport, carbon concentrating mechanism, RuBisCO, glycogen synthesis and light harvesting antenna pigment biosynthesis. In Synechococcus elongates PCC 7942, a non-nitrogen fixing cyanobacteria, expression of a relatively smaller fraction of genes oscillates under LL condition with the major periodicity being 24 h. In contrast, the entire cellular machinery of Cyanothece orchestrates coordinated oscillation in anticipation of the ensuing metabolic phase in both LD and LL. These results may have important implications in understanding the timing of various cellular events and in engineering cyanobacteria for biofuel production. © 2015 Krishnakumar et al.
- Authors: Krishnakumar, Sujatha , Gaudana, Sandeep , Vinh, Nguyen , Viswanathan, Ganesh , Chetty, Madhu , Wangikar, Pramod
- Date: 2015
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 10, no. 5 (2015), p. 1-23
- Full Text:
- Reviewed:
- Description: Unicellular diazotrophic cyanobacteria such as Cyanothece sp. ATCC 51142 (henceforth Cyanothece), temporally separate the oxygen sensitive nitrogen fixation from oxygen evolving photosynthesis not only under diurnal cycles (LD) but also in continuous light (LL). However, recent reports demonstrate that the oscillations in LL occur with a shorter cycle time of ∼11 h. We find that indeed, majority of the genes oscillate in LL with this cycle time. Genes that are upregulated at a particular time of day under diurnal cycle also get upregulated at an equivalent metabolic phase under LL suggesting tight coupling of various cellular events with each other and with the cell's metabolic status. A number of metabolic processes get upregulated in a coordinated fashion during the respiratory phase under LL including glycogen degradation, glycolysis, oxidative pentose phosphate pathway, and tricarboxylic acid cycle. These precede nitrogen fixation apparently to ensure sufficient energy and anoxic environment needed for the nitrogenase enzyme. Photosynthetic phase sees upregulation of photosystem II, carbonate transport, carbon concentrating mechanism, RuBisCO, glycogen synthesis and light harvesting antenna pigment biosynthesis. In Synechococcus elongates PCC 7942, a non-nitrogen fixing cyanobacteria, expression of a relatively smaller fraction of genes oscillates under LL condition with the major periodicity being 24 h. In contrast, the entire cellular machinery of Cyanothece orchestrates coordinated oscillation in anticipation of the ensuing metabolic phase in both LD and LL. These results may have important implications in understanding the timing of various cellular events and in engineering cyanobacteria for biofuel production. © 2015 Krishnakumar et al.
Effects on photosynthetic response and biomass productivity of acacia longifolia ssp. longifolia under elevated CO2 and water-limited regimes
- Javaid, Muhammad, Wang, Xiukang, Florentine, Singarayer, Ashraf, Muhammad, Mahmood, Athar, Li, Feng-Min, Fiaz, Sajid
- Authors: Javaid, Muhammad , Wang, Xiukang , Florentine, Singarayer , Ashraf, Muhammad , Mahmood, Athar , Li, Feng-Min , Fiaz, Sajid
- Date: 2022
- Type: Text , Journal article
- Relation: Frontiers in Plant Science Vol. 13, no. (2022), p.
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- Description: It is known that the impact of elevated CO2 (eCO2) will cause differential photosynthetic responses in plants, resulting in varying magnitudes of growth and productivity of competing species. Because of the aggressive invasive nature of Acacia longifolia ssp. longifolia, this study is designed to investigate the effect of eCO2 on gas exchange parameters, water use efficiency, photosystem II (PSII) activities, and growth of this species. Plants of A. longifolia ssp. longifolia were grown at 400 ppm (ambient) and 700 ppm (elevated) CO2 under 100 and 60% field capacity. Leaf gas exchange parameters, water use efficiency, intrinsic water use efficiency, instantaneous carboxylation efficiency, and PSII activity were measured for 10 days at 2-day intervals. eCO2 mitigated the adverse effects of drought conditions on the aforementioned parameters compared to that grown under ambient CO2 (aCO2) conditions. A. longifolia, grown under drought conditions and re-watered at day 8, indicated a partial recovery in most of the parameters measured, suggesting that the recovery of this species under eCO2 will be higher than that with aCO2 concentration. This gave an increase in water use efficiency, which is one of the reasons for the observed enhanced growth of A. longifolia under drought stress. Thus, eCO2 will allow to adopt this species in the new environment, even under severe climatic conditions, and foreshadow its likelihood of invasion into new areas. Copyright © 2022 Javaid, Wang, Florentine, Ashraf, Mahmood, Li and Fiaz.
- Authors: Javaid, Muhammad , Wang, Xiukang , Florentine, Singarayer , Ashraf, Muhammad , Mahmood, Athar , Li, Feng-Min , Fiaz, Sajid
- Date: 2022
- Type: Text , Journal article
- Relation: Frontiers in Plant Science Vol. 13, no. (2022), p.
- Full Text:
- Reviewed:
- Description: It is known that the impact of elevated CO2 (eCO2) will cause differential photosynthetic responses in plants, resulting in varying magnitudes of growth and productivity of competing species. Because of the aggressive invasive nature of Acacia longifolia ssp. longifolia, this study is designed to investigate the effect of eCO2 on gas exchange parameters, water use efficiency, photosystem II (PSII) activities, and growth of this species. Plants of A. longifolia ssp. longifolia were grown at 400 ppm (ambient) and 700 ppm (elevated) CO2 under 100 and 60% field capacity. Leaf gas exchange parameters, water use efficiency, intrinsic water use efficiency, instantaneous carboxylation efficiency, and PSII activity were measured for 10 days at 2-day intervals. eCO2 mitigated the adverse effects of drought conditions on the aforementioned parameters compared to that grown under ambient CO2 (aCO2) conditions. A. longifolia, grown under drought conditions and re-watered at day 8, indicated a partial recovery in most of the parameters measured, suggesting that the recovery of this species under eCO2 will be higher than that with aCO2 concentration. This gave an increase in water use efficiency, which is one of the reasons for the observed enhanced growth of A. longifolia under drought stress. Thus, eCO2 will allow to adopt this species in the new environment, even under severe climatic conditions, and foreshadow its likelihood of invasion into new areas. Copyright © 2022 Javaid, Wang, Florentine, Ashraf, Mahmood, Li and Fiaz.
Photosynthetic activity and water use efficiency of Salvia verbenaca L. under elevated CO2 and water‐deficit conditions
- Javaid, Muhammad Mansoor, Florentine, Singarayer, Ashraf, Muhammad, Mahmood, Athar, Sattar, Abdul, Wasaya, Allah, Li, Feng‐Min
- Authors: Javaid, Muhammad Mansoor , Florentine, Singarayer , Ashraf, Muhammad , Mahmood, Athar , Sattar, Abdul , Wasaya, Allah , Li, Feng‐Min
- Date: 2022
- Type: Text , Journal article
- Relation: Journal of agronomy and crop science Vol. 208, no. 4 (2022), p. 536-551
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- Description: Investigating the combined effects of elevated CO2 concentration and water‐deficit on weed plants is crucial to gaining a thorough understanding of plant performance and modifying agricultural processes under changing climate conditions. This study examined the effect of elevated CO2 concentration and water‐deficit conditions on leaf gas exchange, water use efficiency, carboxylation efficiency and the photosystem II (PSII) activity of two Salvia verbenaca L., varieties. These varieties were grown under two CO2 concentrations (ambient conditions of 400 ppm and elevated conditions of 700 ppm) and two water regimes (well‐watered [100% field capacity] and water‐deficit conditions [60% field capacity]) in laboratory growth chambers. For 12 days, at 2‐day intervals, (i) leaf gas exchange parameters (photosynthesis rate, stomatal conductance, transpiration rate (E) and intercellular CO2 concentration (Ci)), (ii) water use efficiency (WUE), (iii) intrinsic water use efficiency (IWUE), (iv) instantaneous carboxylation efficiency and (v) PSII activity (fluorescence, quantum yield of PSII, photochemical efficiency of PSII, photochemical quenching and photosynthetic electron transport) were measured. Water‐deficit conditions had negative effects on studied parameters of both varieties, whereas elevated CO2 concentration had positive effects on the gas exchange, water use efficiency and PSII activity of both. Salvia verbenaca varieties grown under water‐deficit conditions from Day 0 to Day 5 showed a partial recovery in most of the parameters when the resumption of the well‐watered regime was reinstituted on Day 6. Salvia verbenaca varieties grown under water‐deficit conditions were re‐watered on day 6 and indicated a partial recovery in all the parameters. A comparison of the two varieties showed that var. vernalis recorded higher values of gas exchange, quantum yield of PSII and photochemical efficiency of PSII than var. verbenaca, but the water use efficiency of var. verbenaca was higher than that of var. vernalis. These differences serve to illustrate the complexity of such studies and suggest that a detailed understanding of the nature of weed infestations is essential if optimum management control is to be practiced. Elevated CO2 concentration mitigated the adverse effects of water‐deficit conditions and thereby enhanced the adaptive mechanism of this weed by improving its water use efficiency. It is thus likely that S. verbenaca has the potential to take advantage of climate change by increasing its relative competitiveness with other plants in drought‐prone areas, suggesting that it could significantly expand its invasive range under such conditions.
- Authors: Javaid, Muhammad Mansoor , Florentine, Singarayer , Ashraf, Muhammad , Mahmood, Athar , Sattar, Abdul , Wasaya, Allah , Li, Feng‐Min
- Date: 2022
- Type: Text , Journal article
- Relation: Journal of agronomy and crop science Vol. 208, no. 4 (2022), p. 536-551
- Full Text:
- Reviewed:
- Description: Investigating the combined effects of elevated CO2 concentration and water‐deficit on weed plants is crucial to gaining a thorough understanding of plant performance and modifying agricultural processes under changing climate conditions. This study examined the effect of elevated CO2 concentration and water‐deficit conditions on leaf gas exchange, water use efficiency, carboxylation efficiency and the photosystem II (PSII) activity of two Salvia verbenaca L., varieties. These varieties were grown under two CO2 concentrations (ambient conditions of 400 ppm and elevated conditions of 700 ppm) and two water regimes (well‐watered [100% field capacity] and water‐deficit conditions [60% field capacity]) in laboratory growth chambers. For 12 days, at 2‐day intervals, (i) leaf gas exchange parameters (photosynthesis rate, stomatal conductance, transpiration rate (E) and intercellular CO2 concentration (Ci)), (ii) water use efficiency (WUE), (iii) intrinsic water use efficiency (IWUE), (iv) instantaneous carboxylation efficiency and (v) PSII activity (fluorescence, quantum yield of PSII, photochemical efficiency of PSII, photochemical quenching and photosynthetic electron transport) were measured. Water‐deficit conditions had negative effects on studied parameters of both varieties, whereas elevated CO2 concentration had positive effects on the gas exchange, water use efficiency and PSII activity of both. Salvia verbenaca varieties grown under water‐deficit conditions from Day 0 to Day 5 showed a partial recovery in most of the parameters when the resumption of the well‐watered regime was reinstituted on Day 6. Salvia verbenaca varieties grown under water‐deficit conditions were re‐watered on day 6 and indicated a partial recovery in all the parameters. A comparison of the two varieties showed that var. vernalis recorded higher values of gas exchange, quantum yield of PSII and photochemical efficiency of PSII than var. verbenaca, but the water use efficiency of var. verbenaca was higher than that of var. vernalis. These differences serve to illustrate the complexity of such studies and suggest that a detailed understanding of the nature of weed infestations is essential if optimum management control is to be practiced. Elevated CO2 concentration mitigated the adverse effects of water‐deficit conditions and thereby enhanced the adaptive mechanism of this weed by improving its water use efficiency. It is thus likely that S. verbenaca has the potential to take advantage of climate change by increasing its relative competitiveness with other plants in drought‐prone areas, suggesting that it could significantly expand its invasive range under such conditions.
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