Effects of Acetylcholine, Cytochalasin B and Amiprophosmethyl on Phloem Transport in Radish （Raphanus sativas）

We investigated the role of the ＂sieve tube-companion cell complex＂ lining the tube periphery, particularly the microfilament and microtubule, in assisting the pushing of phloem sap flow. We made a simple phloem transport system with a living radish plant, in which the conducting channel was exposed for local treatment with chemicals that are effective in modulating protoplasmic movement （acetylcholine, （ACh） a neurotransmitter in animals and insects; cytochalasin B, （CB） a specific inhibitor of many cellular responses that are mediated by microfilament systems and amiprophos-methyl, （APM） a specific inhibitor of many cellular responses that are mediated by microtubule systems）. Their effects on phloem transport were estimated by two experimental devices： （i） a comparison of changes in the amount of assimilates in terms of carbohydrates and ^14C-labeled photosynthetic production that is left in the leaf blade of treated plants; and （ii） distribution patterns of ^14C-labeled leaf assimilates in the phloem transport system. The results indicate that CB and APM markedly inhibited the transfer of photosynthetic product from leaf to root via the leaf vein, while ACh enhanced the transfer of photosynthetic product in low concentrations （5.0×10^-4 mol/L） but inhibited it in higher concentrations （2.0×10^-3 mol/L） from leaf to root via the leaf vein. Autoradiograph imaging clearly reveals that ACh treatment is more effective than the control, and both CB and APM treatments effectively inhibit the passage of radioactive assimilates. All of the results support the postulation that the peripheral protoplasm in the sieve tube serves not only as a passive semi-permeable membrane, but is also directly involved in phloem transport.

Changes of Secondary Metabolites and Trace Elements in Gentiana macrophylla Flowers: A Potential Medicinal Plant Part

Objective To search for the potential medicinal plant part of Gentiana macrophyllabased on changes of secondary metabolites and trace elements in the flowers of G.macrophylla.Methods HPLC was used to detect the changes of the active constituents（longanic acid,sweroside,gentiopicroside,and swertiamarin）and ICP-AES was used for mineral nutrients in G.macrophylla during flower development.And soluble sugar,starch,crude protein,hemicelluloses,cellulose,and lignin were determined.Results Biomass of flower in full bloom（D2）phase was considerable during flower development,in which the contents of longanic acid and gentiopicroside were at the highest levels with 2.65 and 2.88 times higher than those recorded in Chinese Pharmacopoeia 2010,sweroside and swertiamarin in the flowers were reaching 6.06 and 1.25 times higher than those in roots.Florescence is the most valuable stage during flower development.The concentration of Fe,Mg,K,P,and B was higher in the flowers than that in roots.The accumulation of active constituents in the plant was influenced by the contents of metabolically linked carbon and nitrogen compounds.Conclusion The secondary metabolites,mineral nutrients,and physicochemical indicators are tightly regulated by flower organ development,D2 is an important stage for both biomass and extraction of active constituents such as longanic acid.The flowers of G.macrophylla could be used as a potential medicinal plant part for longanic acid at a high level.