毛竹快速生长期茎秆不同节间光合色素和光合酶活性的差异

为揭示毛竹(Phyllostachysedulis)快速生长期茎秆中的光合碳同化特征及其在不同节间的变化规律,以毛竹笋竹茎秆为材料,测定不同节间光合色素含量、核酮糖-1,5-二磷酸羧化酶/加氧酶(Rubisco)、磷酸烯醇式丙酮酸羧化酶(PEPC)、苹果酸脱氢酶(NADP-MDH)、NADP-苹果酸酶(NADP-ME)、磷酸烯醇式丙酮酸羧激酶(PEPCK)以及丙酮酸磷酸双激酶(PPDK)活性。结果显示,茎秆中叶绿素a、叶绿素b以及类胡萝卜素含量随节间升高均呈下降趋势,叶绿素a/b比值呈逐渐上升趋势;随着节间的升高,茎秆中Rubisco、PEPC和PPDK活性在第1–10节间显著下降,之后酶活性降幅逐渐减缓;NADP-ME活性在第1–13节间呈显著下降趋势,之后酶活性趋于平稳;NADP-MDH活性在第1–25节间显著下降。PEPC/Rubisco活性比值随节间升高而不断增加,其范围介于18.37–65.09之间,明显大于典型C3植物中的活性比值。上述结果表明,茎秆不同节间的光合碳同化能力存在明显差异,中、下部节间生长相对较快;茎秆中存在多种C4酶且活性较高,这为此时期茎秆中存在C4光合途径提供了有力证据。

Differences in Photosynthetic Pigments and Photosynthetic Enzyme Activities in Different Internodes of Phyllostachys edulis During Rapid Growth Stage

This study aimed to reveal the characteristics of photosynthetic carbon assimilation and the change regulation in different internodes of Phyllostachys edulis stems during their rapid growth stage. We analyzed the photosynthetic pigment content and activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), phosphoenolpyruvate carboxylase (PEPC), NADP-malate dehydrogenase (NADP-MDH), NADP-malic enzyme (NADP-ME), phosphoenolpyruvate carboxykinase (PEPCK) and pyruvate, and orthophosphate dikinase (PPDK) in stems with different internodes. With increasing internode number of P. edulis stems, the content of chlorophyll a, chlorophyll b and carotenoid was all significantly reduced and the ratio of chlorophyll a/b showed a gradual upward trend. The activities of Rubisco, PEPC and PPDK in stems of P. edulis decreased significantly from the 1^st to the 10^th internode, then the rate of decrease gradually slowed down. The activities of NADP-ME declined significantly from the 1^st to the 13^th internode; after the 13^th internode, the enzyme activities tended to be stable. The activities of NADP-MDH decreased markedly from 1^st to the 25^th internode of stems. The ratio of PEPC/Rubisco increased gradually and the range was between 18.37 and 65.09, which was significantly larger than that in typical C₃ plants. The research showed that the assimilating capacity with carbon differed in different internodes, and the middle and lower stems grew relatively fast. The result of many C₄ enzymes and activities being significantly high provided strong evidence for the existence of a C₄ photosynthetic pathway in the stems of P. edulis.