ABSTRACT
We investigated the effects of granulation on organic acid metabolism and its relation to mineral elements in 'Guanximiyou' pummelo (Citrus grandis) juice sacs. Granulated juice sacs had decreased concentrations of citrate and isocitrate, thus lowering juice sac acidity. By contrast, malate concentration was higher in granulated juice sacs than in normal ones. The reduction in citrate concentration might be caused by increased degradation, as indicated by enhanced aconitase activity, whilst the increase in malate concentration might be caused by increased biosynthesis, as indicated by enhanced phosphoenolpyruvate carboxylase (PEPC). Real time quantitative reverse transcription PCR (qRT-PCR) analysis showed that the activities of most acid-metabolizing enzymes were regulated at the transcriptional level, whilst post-translational modifications might influence the PEPC activity. Granulation led to increased accumulation of mineral elements (especially phosphorus, magnesium, sulphur, zinc and copper) in juice sacs, which might be involved in the incidence of granulation in pummelo fruits.
Subject(s)
Acids, Acyclic/metabolism , Beverages/analysis , Citrus/chemistry , Food Handling , Fruit/chemistry , Trace Elements/analysis , Acids, Acyclic/analysis , Aconitate Hydratase/genetics , Aconitate Hydratase/metabolism , China , Citric Acid/analysis , Citric Acid/metabolism , Citrus/enzymology , Citrus/metabolism , Copper/analysis , Enzyme Stability , Fruit/enzymology , Fruit/metabolism , Gene Expression Regulation, Enzymologic , Isocitrates/analysis , Isocitrates/metabolism , Magnesium/analysis , Malates/analysis , Malates/metabolism , Particle Size , Phosphoenolpyruvate Carboxylase/biosynthesis , Phosphoenolpyruvate Carboxylase/genetics , Phosphoenolpyruvate Carboxylase/metabolism , Phosphorus/analysis , Plant Proteins/biosynthesis , Plant Proteins/genetics , Plant Proteins/metabolism , Sulfur/analysis , Zinc/analysisABSTRACT
The study is aimed to make the most of available space of Dendrobium officinale cultivation facility, reveal the yield and functional components variation of stereoscopic cultivated D. officinale, and improve quality, yield and efficiency. The agronomic traits and yield variation of stereoscopic cultivated D. officinale were studied by operating field experiment. The content of polysaccharide and extractum were determined by using phenol-sulfuric acid method and 2010 edition of "Chinese Pharmacopoeia" Appendix X A. The results showed that the land utilization of stereoscopic cultivated D. officinale increased 2.74 times, the stems, leaves and their total fresh or dry weight in unit area of stereoscopic cultivated D. officinale were all heavier than those of the ground cultivated ones. There was no significant difference in polysaccharide content between stereoscopic cultivation and ground cultivation. But the extractum content and total content of polysaccharide and extractum were significantly higher than those of the ground cultivated ones. In additional, the polysaccharide content and total content of polysaccharide and extractum from the top two levels of stereoscopic culture matrix were significantly higher than that of the ones from the other levels and ground cultivation. Steroscopic cultivation can effectively improves the utilization of space and yield, while the total content of polysaccharides and extractum were significantly higher than that of the ground cultivated ones. The significant difference in Dendrobium polysaccharides among the plants from different height of stereo- scopic culture matrix may be associated with light factor.
