摘 要 ：在被子植物中,从谷氨酰-tRNA到叶绿素的生物合成是由许多酶催化的级联反应,其中间代谢产物具有较强的光反应活性和细胞毒性,因此这一过程在细胞内受到严格的调控。本研究通过检测宽叶吊兰叶片叶绿素生物合成途径的14种中间产物含量随昼夜节律的变化,探讨昼夜节律对宽叶吊兰叶绿素生物合成的影响。结果表明,中间产物ALA( δ-氨基乙酰丙酸)、PBG(胆色素原)、Proto Ⅸ(原卟啉Ⅸ)、Heme(血红素)、Mg-Proto Ⅸ(镁原卟啉 Ⅸ)、Chlide a (叶绿素酸酯a)、Chlide b (叶绿素酸酯b)、Chl a (叶绿素a)、Chl b (叶绿素b)受光诱导,而Urogen Ⅲ(尿卟啉 Ⅲ)、Coprogen Ⅲ(粪卟啉 Ⅲ)和Pchlide (原叶绿素酸脂)受黑暗诱导,尤其是Pchlide在黑暗中的积累量显著增加;Mpe (镁原卟啉Ⅸ单甲酯)和Mpde (镁原卟啉Ⅸ二酯)具有2个积累峰值,分别出现在中午12:00和夜间24:00。说明叶绿素生物合成受昼夜节律的调控,但其中间代谢产物含量的变化规律与昼夜节律并不完全一致。
Abstract:The process of chlorophyll biosynthesis is catalyzed by a series of enzymes and strictly regulated in angiosperms. In this paper, the effect of the circadian rhythm on chlorophyll biosynthesis in Chlorophytum capense (L.) Kuntze was investigated, and the diurnal variations of 14 precursors following changes in the circadian rhythm were monitored. Results showed that ALA ( δ-aminolaevulinic acid), PBG (porphobilinogen), Proto Ⅸ(protoporphyrin Ⅸ), heme, Mg-Proto Ⅸ(Mg-protoporphyrin Ⅸ), Chlide a (chlorophyllide a), Chlide b (chlorophyllide b), chlorophyll a and chlorophyll b were induced by light.Urogen Ⅲ(uroporphyrin Ⅲ), Coprogen Ⅲ(coproporphyrin Ⅲ) and Pchlide(protochlorophyllide)were induced by darkness, in particular Pchlide accumulation increased significantly in the dark. Both Mpe (Mg-proto monomethyl ester) and Mpde (Mg-protoporphyrin Ⅸ diester) had two accumulation peaks at 12:00 and 24:00, respectively. This paper demonstrated that chlorophyll biosynthesis was significantly regulated by the circadian rhythm, but different precursors followed different rules.