中国水稻科学

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外源C4二羧酸对转玉米PEPC基因水稻C4光合途径的促进作用

朱素琴1; 季本华1,2; 焦德茂2   

  1. 1南通师范学院 生命科学与技术系, 江苏 南通 226007; 2江苏省农业科学院 农业生物遗传生理研究所, 江苏 南京 210014
  • 收稿日期:1900-01-01 修回日期:1900-01-01 出版日期:2004-07-10 发布日期:2004-07-10

Promotive Effect of Exogenous C4-Bicarboxylate on Photosynthetic C4 Pathway in Transgenic Rice Plant Expressing Maize Specific PEPC Gene

ZHU Su-qin 1; JI Ben-hua 1; 2; JIAO De-mao2   

  1. 1Department of Life Sciences and Technology; Nantong Normal College; Nantong 226007; China; 2Institute of Agrobiological Genetics and Physiology; Jiangsu Academy of Agricultural Sciences; Nanjing 210014; China
  • Received:1900-01-01 Revised:1900-01-01 Online:2004-07-10 Published:2004-07-10

摘要: 以转PEPC基因水稻和野生型水稻Kitaake为材料, 研究了不同基因型水稻叶片中的C4光合微循环及其功能。通过测定与光合C4途径有关的关键酶,如磷酸烯醇式丙酮酸羧化酶(PEPC)、NADP苹果酸酶(NADP-ME)、NADP苹果酸脱氢酶(NADP-MDH)和丙酮酸磷酸双激酶(PPDK),说明野生型水稻叶片中具有完整的C4光合酶体系;用外源草酰乙酸(OAA)或苹果酸(MA)饲喂叶切片或叶绿体后明显增加光合速率,证明野生型水稻中具有一个有限的光合C4微循环。将玉米的PEPC基因导入原种水稻后,可大幅度提高光合C4微循环的速率。测定不同基因型的CO2交换速率,看出水稻中C4光合微循环的增强有提高净光合速率(Pn)和降低Pr/Pn比值的作用。叶绿素荧光特性分析表明,C4光合微循环的增强伴随着PSⅡ电子传递效率(Fv/Fm)和光化学猝灭(qp)的增加,以及非光化学猝灭(qN)的降低。 

关键词: C4二羧酸, 叶绿素荧光特性, 磷酸烯醇式丙酮酸羧化酶, C4光合途径, 转基因水稻

Abstract: Photosynthetic C4 microcycle and its function in different genotype rices were explored comparatively using PEPC transgenic rice (PC) and homozygous wild genotype rice (WT) Kitaake as experimental materials. In WT rice, there existed an intact C 4 photosynthetic enzyme system which were verified through detecting photosynthetic C4 pathway related key enzymes, i.e. phosphoenol pyruvate carboxylase (PEPC), NADP malic enzyme (NADP ME), NADP malate dehydrogenase (NADP MDH) and pyruvate, orthophosphate dikinase (PPDK), and a primitively limited photosynthetic C 4 microcycle pathway through assaying increased photosynthetic rate in leaf discs or chloroplasts fed with exogenous oxaloacetate (OAA) or malate (MA). Furthermore, photosynthetic C 4 microcycle was promoted in a great range in PC rice. Enhancement of photosynthetic C4 microcycle further played some role in raising the net photosynthetic rates (Pn) and debasing the ratio of photorespiratory rate and net photosynthetic rate( Pr/Pn ), which were comfirmed through determining the CO2 gas exchange rate in different genotype rices, WT or PC. Analyzing the chlorophyll fluorescence characteristics showed that enhancement of photosynthetic C4 microcycle companied with the raising PSⅡelectron transport efficiency (Fv /Fm ) and photochemical quenching (q p ), and the lowering of non photochemical quenching (q N ). These results will provide scientific evidence for genetic breeding to improve photosynthetic efficiency in crops by gene engineering.

Key words: C4 bicarboxylate, chlorophyll fluorescence characteristic, phosphoenol pyruvate carboxylase, photosynthetic C4 pathway, transgenic rice