八宝属(Crassulaceae)一新变种

Ｈｙｌｏｔｅｌｅｐｈｉｕｍ　ａｎｇｕｓｔｕｍ（Ｍａｘｉｍ）Ｈ．Ｏｈｂａｖａｒ－ｐｏＪ．Ｍ．Ｚｈａｎｇ耐丑．Ｔ．Ｆｕ,ｖａｒ．ｎｏｖ．Ａｔｎ出ｄ江ＤｒｔｗｈｏＤ回ｒ巴ｌｌｔｉａａｘｉｌｌａｒｅｓ３—５,ｐｅｕｎｃｕｌｉｓ８。１２ｃｍｌｏｎｇｉｓ．Ｓｈａ...     

The appearance of a new molecular species of phosphoenolpyruvate carboxylase (PEPC) and the rapid induction of CAM in Sedum telephium L.

Abstract. When detached leaves of Sedum telephium are incubated in the absence of water, a rapid switch from C₃ photosynthesis to CAM (as indicated by the onset of day-to-night fluctuations in titratable acidity. ΔH⁺) occurs within the first dark period. The C₃-CAM switch in intact plants occurs within 3 5d. Extractable activity of phospho enol pyruvate carboxylase (PEPC) increases five-fold in intact plants during CAM induction; however, during rapid CAM induction in detached leaves, there is only a very small increase in PEPC activity. Fractionation by anion exchange chromatography of crude extracts from leaves of intact plants subjected to water deficit shows that CAM induction is associated with the appearance of a molecular species of PEPC termed PEPC I. PEPC I is barely detectable in well-watered plants which are not performing CAM. The major form in these plants is termed PEPC II. In leaves from intact plants, there is a significant positive correlation between PEPC I activity and ΔH⁺ during a period of increasing water deficit. PEPC I exhibits day to night fluctuations in malate sensitivity, being less sensitive during the dark period. In contrast, PEPC II is more sensitive to inhibition by malate and has no day to night fluctuation in sensitivity. In detached leaves deprived of water, a small increase in PEPC I capacity is detected at the end of the first dark period (20 h after the start of treatment). The results suggest that PEPC I is required for attainment of maximum nocturnal malic acid synthesis. There is a significant correlation between leaf water status (relative water content), ΔH⁺, total PEPC and PEPC I activity suggesting that the internal water status of the plant may be a trigger for CAM induction. Abscisic acid applied to detached leaves does not cause nocturnal acidification.     

四川阿坝产野生大花红景天不同器官中红景天苷含量的比较

大花红景天[Rhodiola crenulata（Hook.f.et Thoms）H．Ohba]为药材红景天的基原植物,是珍稀的药食兼用天然植物资源之一[1-2]。红景天具有益气活血、通脉平喘、扶正固本的作用[1],主要含黄酮类、有机酸类、多糖类、苷类、香豆素类和挥发性成分等,其中包含的重要生物活性成分有红景天苷、红景天素、酪醇、二苯甲基六氢吡啶和超氧化物歧化酶（SOD）等,还含有维生素及人体必需的多种大量和微量元素,营养价值极高[3-5]。红景天具有抗疲劳、抗缺氧、强壮机体、抗心肌缺血、抗肿瘤和保护神经细胞等作用,红景天药材或其提取物已成为多种中成药、食品、饮料和化妆品的重要原料旧[6]。     

Physiological responses,tolerance efficiency,and phytoextraction potential of Hylotelephium spectabile (Boreau) H. Ohba under Cd stress in hydroponic condition

Abstract

A sand hydroponic experiment with different concentrations of 0, 5, 10, 20, 40?mg L^?1 Cd was used to study the growth and physiological response of Hylotelephium spectabile (Boreau) H. Ohba. and its phytoextraction potential for Cd. The results showed that total plant biomass under 5?mg L^?1 Cd treatment was slightly affected. The content of malondialdehyde (MDA) in leaf exposed to Cd was higher, and the POD and CAT activity exhibited a positive response to the low level of Cd addition (5?mg·L^?1). The photosynthesis pigments were slightly inhibited, and the ultrastructure of chloroplast remained intact after treatment with 10?mg L^?1 Cd. The maximum leaf Cd content (603?mg·kg^?1) was found in 5?mg L^?1 Cd treatment, then decreased with the Cd level increased. The maximum Cd content in the shoots far exceeds the threshold level (100?mg kg^?1) for a Cd-hyperaccumulator plant with the value of translocation factor (TF_shoot/root) for Cd reaching up to 5.62. In conclusion, H. spectabile showed normal growth and physiological response and high shoot Cd accumulation under 5?mg L^?1 Cd stress, which made it to be a good candidate for phytoextraction of low-level Cd polluted environment.