Effects of elevated CO2 on growth, carbon assimilation, photosynthate accumulation and related enzymes in rice leaves during sink-source transition.
To study the effects of growing rice (Oryza sativa L.) leaves under the treatment of the short-term elevated CO(2) during the period of sink-source transition, several physiological processes such as dynamic changes in photosynthesis, photosynthate accumulation, enzyme activities (sucrose phosphate synthase (SPS), and sucrose synthase (SS)), and their specific gene (sps1 and RSus1) expressions in both mature and developing leaf were measured. Rice seedlings with fully expanded sixth leaf (marked as the source leaf, L6) were kept in elevated (700 micromol/mol) and ambient (350 mol/L) CO(2) until the 7th leaf (marked as the sink leaf, L7) fully expanded. The results demonstrated that elevated CO(2) significantly increased the rate of leaf elongation and biomass accumulation of L7 during the treatment without affecting the growth of L6. However, in both developing and mature leaves, net photosynthetic assimilation rate (A), all kinds of photosynthate contents such as starch, sucrose and hexose, activities of SPS and SS and transcript levels of sps1 and RSus1 were significantly increased under elevated CO(2) condition. Results suggested that the elevated CO(2) had facilitated photosynthate assimilation, and increased photosynthate supplies from the source leaf to the sink leaf, which accelerated the growth and sink-source transition in new developing sink leaves. The mechanisms of SPS regulation by the elevated CO(2) was also discussed.
Li
Jun-Ying
JY
College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Liu
Xing-Hua
XH
Cai
Qing-Sheng
QS
Gu
Hui
H
Zhang
Shan-Shan
SS
Wu
Yan-Yan
YY
Wang
Chun-Jiao
CJ
D050260:Carbohydrate Metabolism / Q000187:drug effects; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000494:pharmacology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D012275:Oryza / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D010788:Photosynthesis / Q000187:drug effects*; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism
D010940:Plant Proteins; D002245:Carbon Dioxide; D002244:Carbon; D005964:Glucosyltransferases; C022699:sucrose synthase; C022698:sucrose-phosphate synthase