[Study on the net photosynthesis rate of Coptis chinensis from different types and production places].

OBJECTIVE: Evaluate the photosynthesis characteristics of Coptis chinensis and provide theoretical basis for the optimization of Coptis chinensis germplasm resources and variety. METHODS: The daily variation of the net photosynthetic rate, transpiration rate, stomatal conductance and intercellular CO2 density in leaf blade were determined by Photosynthesis analyzer, and the net photosynthesis rate of Coptis chinensis from different plant ages, types and production places was compared. RESULTS: The light saturation point in Coptis chinensis was about 500 micromol/m2 x s, light compensation point was about 12.04 micromol/(m2 x s), apparent quantum yield was 0.011. When the temperature was above 33 degrees C, the transpiration rate increased but the net photosynthesis rate decreased. There was no significant difference (P > 0.05) among the net photosynthesis rate of Coptis chinensis from different plant ages. The net photosynthesis rate of the type DA-YE and ZHI-HUA was significantly higher than that of other types (P < 0.05); The net photosynthesis rates of specimens from Fubao mountain in Lichuan county of Hubei and Fengmu village in Shizhu county of Chongqing were significantly higher than that of others. CONCLUSIONS: The net photosynthesis rate of Coptis chinensis decreased under hight temperation and hight light. Different germplasm resources of Coptis chinensis, the net photosynthetic rate had certain differences.

Bowman-birk proteinase inhibitor confers heavy metal and multiple drug tolerance in yeast.

Cultured Coptis japonica cells show tolerance to various toxic compounds. By yeast functional screening of cadmium (Cd) plates with its cDNA library, we isolated a gene encoding Bowman-Birk proteinase inhibitor (CjBBI). The yeast transformant of CjBBI showed multiple tolerance to various drugs adding to Cd, and revealed reduced Cd accumulation in cells. Preferential organs for Cjbbi expression were aerial parts of intact plants, and the subcellular localization of CjBBI was shown, using its green fluorescent protein fusion, to be the apoplast. Induction of Cjbbi expression by Cd treatment suggested that CjBBI was responsible for the tolerance to Cd observed in C. japonica cells.

Characterization of vacuolar transport of the endogenous alkaloid berberine in Coptis japonica.

Alkaloids comprise one of the largest groups of plant secondary metabolites. Many of them exhibit strong biological activities, and, in most cases, they are accumulated in the central vacuole of alkaloid-producing plants after synthesis. However, the mechanisms involved in alkaloid transport across the tonoplast are only poorly understood. In this study, we analyzed the vacuolar transport mechanism of an isoquinoline alkaloid, berberine, which is produced and accumulated in the vacuole of cultured cells of Coptis japonica. The characterization of berberine transport using intact vacuoles and a tonoplast vesicle system showed that berberine uptake was stimulated by Mg/ATP, as well as GTP, CTP, UTP, and Mg/pyrophosphate. Berberine uptake was strongly inhibited by NH4(+) and bafilomycin A1, while vanadate, which is commonly used to inhibit ATP-binding cassette transporters, had only a slight effect, which suggests the presence of a typical secondary transport mechanism. This is contrary to the situation in the plasma membrane of this plant cell, where the ATP-binding cassette transporter is involved in berberine transport. Model experiments with liposomes demonstrated that an ion-trap mechanism was hardly implicated in berberine transport. Further studies suggested that berberine was transported across the tonoplast via an H+/berberine antiporter, which has a Km value of 43.7 microM for berberine. Competition experiments using various berberine analogs, as well as other classes of alkaloids, revealed that this transporter is fairly specific, but not exclusive, for berberine.