| Full text | |
| Author(s): |
Moreira Lobo, Ana Karla
[1]
;
Martins, Marcio de Oliveira
[1]
;
Lima Neto, Milton Costa
[1]
;
Machado, Eduardo Caruso
[2]
;
Ribeiro, Rafael Vasconcelos
[3]
;
Gomes Silveira, Joaquim Albenisio
[1]
Total Authors: 6
|
| Affiliation: | [1] Univ Fed Ceara, Dept Bioquim & Biol Mol, Lab Metab Plantas, BR-60440970 Fortaleza, Ceara - Brazil
[2] Inst Agron IAC, Ctr Pesquisa & Desenvolvimento Ecofisiol & Biofis, Lab Fisiol Vegetal Coaracy M Franco, BR-13012970 Campinas, SP - Brazil
[3] Univ Campinas UNICAMP, Inst Biol, Dept Plant Biol, BR-13083862 Sao Paulo - Brazil
Total Affiliations: 3
|
| Document type: | Journal article |
| Source: | Journal of Plant Physiology; v. 179, p. 113-121, MAY 1 2015. |
| Web of Science Citations: | 19 |
| Abstract | |
Photosynthetic modulation by sugars has been known for many years, but the biochemical and molecular comprehension of this process is lacking. We studied how the exogenous sucrose supplied to leaves could affect sugar metabolism in leaf, sheath and stalk and inhibit photosynthesis in four-month old sugarcane plants. Exogenous sucrose 50 mM sprayed on attached leaves strongly impaired the net CO2 assimilation (P-N) and decreased the instantaneous carboxylation efficiency (P-N/Ci), suggesting that the impairment in photosynthesis was caused by biochemical restrictions. The photosystem II activity was also affected by excess sucrose as indicated by the reduction in the apparent electron transport rate, effective quantum yield and increase in non-photochemical quenching. In leaf segments, sucrose accumulation was related to increases in the activities of soluble acid and neutral invertases, sucrose synthase and sucrose phosphate synthase, whereas the contents of fructose increased and glucose slightly decreased. Changes in the activities of sucrose hydrolyzing and synthesizing enzymes in leaf, sheath and stalk and sugar profile in intact plants were not enough to identify which sugar(s) or enzyme(s) were directly involved in photosynthesis modulation. However, exogenous sucrose was able to trigger down-regulation in the Rubisco abundance, activation state and enzymatic activity. Despite the fact that P-N/Ci had been notably decreased by sucrose, in vitro activity and abundance of PEPCase did not change, suggesting an in vivo modulation of this enzyme. The data reveal that sucrose and/or other derivative sugars in leaves inhibited sugarcane photosynthesis by down-regulation of Rubisco synthesis and activity. Our data also suggest that sugar modulation was not exerted by a feedback mechanism induced by the accumulation of sugars in immature sugarcane stalk. (C) 2015 Published by Elsevier GmbH. (AU) | |
| FAPESP's process: | 08/57495-3 - Integrating physiological, morphological and anatomical traits to understand the differential sucrose yield in sugarcane genotypes |
| Grantee: | Eduardo Caruso Machado |
| Support Opportunities: | Program for Research on Bioenergy (BIOEN) - Thematic Grants |