The Changes of Metabolic Pathways and the Regulato...

The Changes of Metabolic Pathways and the Regulatory Action of an Endogenous Inhibitor in the Developing Siliques of Brassica Napus Linn[1]

Abstract

Activities of the isolated enzymes of the EMP and HMP pathways vary with the stages of development of siliques.From budding to flowering，the activities of both pathways increase，but the activities of enzymes of the EMP pathway increase relatively more than those of the HMP pathway.From flowering to fruiting and to silique maturation，the activities of the EMP enzymes decline rapidly，whereas the activities of the HMP enzymes increase sharply，and remain at that level or only show a slight decrease till the approach of full maturation.

Collateral evidence has been obtained in respiration studies with inhibitors.

The shift from the metabolic predominance of the EMP pathway to the HMP pathway in the siliques takes place between 10 to 20 or more days after flowering，coincident with the time of rapid fat accumulation.(https://www.daowen.com)

C N Shih（施教耐），Y S Zhu（朱雨生），and C Tan（谭常），Institute of Plant Physiology，Academia Sinica.此文发表于1966年“Scientia Sinica”15卷3期379-393页.

Abbreviations used in this paper are：EMP，Embden-Meyerhof-Parnas；HMP，hexose monophosphate；TCA，tricarboxylic acid cycle；NADP，oxidized form of nicotinamide adenine dinucleotide phosphate；NADPH2，its reduced form；NAD，oxidized form of nicotinamide adenine dinucleotide；NADH2，its reduced form；G-6-P，glucose-6-phosphate；6-PG，6-phosphogluconate；R-5-P，ribose-5-phosphate；Xu-5-P，xylulose-5-phosphate；F-6-P，fructose-6-phosphate；FDP，fructose，1，6-diphosphate；3-PG，3-phosphoglyceraldehyde；3-PGA，3-phosphoglycerate；2，3-DPGA，2，3-diphosphoglycerate；EDTA，ethylene diamine tetraacetate；G-6-P DH，G-6-P dehydrogenase；6-PG DH，6-PG dehydrogenase；R-5-P'TE'，enzymes utilizing R-5-P；3PGA DH，3-PG dehydrogenase；ATP，adenosine triphosphate.

A natural inhibitor of G-6-P dehydrogenase and 6-PG dehydrogenase was found in the reproductive organs.It is present mainly in the buds，flowers，and young siliques，and is nearly absent in the old siliques（＞20 days）.There seems to be a correlation between the activity of this inhibitor on the glucose degradative pathways and seed fat formation.Preliminary investigations indicate that the inhibitor is probably a flavonoid or its derivative.