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Details van artikel 15 van 21 gevonden artikelen
| Titel: |
Response of Rice to p(CO2) Enrichment |
| Auteur: |
Seneweera, S. Makino, A. Mae, T. Basra, A. S. |
| Verschenen in: |
Journal of crop improvement |
| Paginering: | Jaargang 13 (2005) nr. 1-2 pagina's 31-53 |
| Jaar: |
2005-06-06 |
| Inhoud: |
Rice (Oryza sativa L.) is grown in many different agro-ecological zones and it assimilates CO2 directly through C3 photosynthesis. At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average. However, this increase is not sustained during prolonged exposure and is associated with reduced amounts of ribulose-1-5-bisphospate carboxylase/oxygenase (Rubisco) content and its maximum potential activity (Vcmax). Rubisco content and Vcmax were reduced by 33 and 22%, respectively, at elevated p(CO2) and this has an additive effect on leaf photosynthesis. Activation state of the Rubisco is also decreased by elevated p(CO2) but no deactivation of Rubisco occurs in rbc S antisense rice with 40% wild type Rubisco suggesting that deactivation is an optimize response. Large amounts of Rubisco (about 80-90%) is synthesized prior to full expansion of leaf when sugar accumulation is minimal. After the leaf has fully expanded, very little Rubisco (about 10-20%) is synthesized and a large amount of sugar accumulates during this period. Therefore, it is unlikely that downregulation of Rubisco at elevated p(CO2) is caused by decreasing the mRNA transcripts for Rubisco small subunit (rbcS) and Rubisco large subunit (rbcL) through soluble sugars. It is more likely that elevated p(CO2) mediated decline in Rubisco is due to rapid degradation of protein and lower nitrogen (N) allocation to Rubisco due to reduced N afflux. Leaf N content was reduced by 16% in plants grown at elevated p(CO2) though leaf N to Rubisco ratio remained consistently unchanged regardless of growth p(CO2) suggesting that N assimilation, distribution and remobilization at the whole plant level is tightly controlled at elevated p(CO2). Further, changes in N and C metabolisms at elevated p(CO2) are likely to reduce the critical N concentration by 30% at elevated p(CO2). |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 15 van 21 gevonden artikelen
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