采收期和贮藏温度对金艳猕猴桃品质的影响

研究了金艳猕猴桃(Actinidia chinensis ×A. eriantha) 4个不同采收期(Ⅰ~Ⅳ)在常温[(23±1)℃]贮藏60 d,以及低温(4℃)贮藏2、4、6月后常温货架14 d内果实品质和果肉色彩的变化。结果表明：采收期Ⅰ和Ⅳ的果实在常温贮藏过程中呼吸高峰出现早、失重快,可滴定酸(TA)、维生素C(Vc)含量和果肉硬度迅速下降;而采收期Ⅱ和Ⅲ的果实呼吸高峰出现晚,保持了较高的TA、Vc含量和果肉硬度。4个采收期猕猴桃果实在常温贮藏期间,果实亮度L*、色度C*和色彩角h显著降低;而在低温贮藏后常温货架期间,果实色彩角h相对于亮度L*和色度C*变化更加明显。研究表明,采收期Ⅱ和Ⅲ为金艳猕猴桃的适宜采收期,色彩角h可以作为适宜的指标反映猕猴桃果实的后熟与衰老,而低温贮藏6个月金艳猕猴桃仍能保持较好的食用品质和色彩。     

爬山虎红色素的大孔树脂吸附和分离及理化性质研究

本文比较了六种不同型号的大孔树脂对爬山虎红色素的吸附能力,筛选其中最佳的HPD600树脂作为爬山虎红色素的吸附和分离的树脂;用甲醇作为洗脱剂,洗脱效果好;研究了食品中几种常见的共存物、几种金属离子、氧化剂、温度及光等对爬山虎红色素稳定性的影响。     

供氮水平对爬山虎（Parthenocissus tricuspidata Planch）生物量及养分分配的影响

爬山虎是典型的亚热带木本攀援植物,在垂直绿化、植被恢复和水土保持等方面的应用日益普遍,而营养元素对爬山虎生长的影响还缺乏研究,这不利于爬山虎的生长调控与合理应用。通过水培试验,对不同氮素水平（0、0.15、0.3、0.45、0.6、0.75 g•L-1）条件下爬山虎幼苗生长、氮磷钾营养分配和利用状况作了研究。结果表明：供氮水平的提高能显著促进植株的生物量增加,并影响茎叶的生物量分配比例,供氮处理的叶生物量占总生物量的50%以上;供氮水平的提高能增加植株根、茎、叶的氮含量,对磷含量影响不显著,对茎叶中的钾含量有一定的稀释作用;叶片是主要的氮养分贮存器官,叶片氮累积量达到整个植株总氮累积量的60%以上;供氮水平的增加,降低了爬山虎的氮利用率,提高了磷钾的利用率。     

蛇葡萄素提取工艺研究

本文利用新方法从中药粤蛇葡萄中提取其主要化学成分蛇葡萄素,收率达１０％。     

Somatic embryogenesis and plant regeneration from petioles of Parthenocissus tricuspidata planch

Summary A protocol of somatic embryogenesis and plant regeneration from petiole segments of Parthenocissus tricuspidata Planch. has been developed. Embryogenic tissue was induced on B5 (Gamborg) basal medium supplemented with 2.25–9.0 μM 2,4-dichlorophenoxyacetic acid, 500 mg l⁻¹ casein hydrolysate (CH), and 0.1 gl⁻¹ activated charcoal. Somatic embryos were induced on B5 medium containing various concentrations of benzyladenine (BA) (4.44, 6.66, and 8.88 μM) and α-naphthaleneacetic acid (NAA) (0, 0.54, and 1.61 μM) plus 500 mg l⁻¹ CH. Ninety percent of normal somatic embryos were converted into plantlets directly on Murashige and Skoog (MS) medium free of plant growth regulators. Shoots could be induced from abnormal somatic embryos on MS medium containing 4.44 μM BA, 0.05 μM NAA, and 500 mg l⁻¹ CH. Genotypic differences were found in the process of somatic embryogenesis and plant regeneration. Histological analysis confirmed the process of somatic embryogenesis. Regenerated plantlets with well-developed roots were successfully acclimatized in greenhouse and all plants showed normal morphological characteristics.     

Effects of Ulmus davidiana planch on mineralization, bone morphogenetic protein-2, alkaline phosphatase, type I collagen, and collagenase-1 in bone cells

Summary Ulmus davidiana Planch (Ulmaceae) (UD) long has been known to have anti-inflammatory and protective effects on damaged tissue, inflammation, and bone among other functions. The herbal medicine also is being used in Oriental medicine to treat osteoporosis. In a preliminary study, treatment of osteoclasts containing long bone cells with the water extract of UD bark prevented the intracellular maturation of cathepsin K (cat K), and thus, it was considered that UD is a pro-drug of a potent bone-resorption inhibitor. To further clarify the role of UD in ossification, we investigated the effects of UD on the proliferation and differentiation of osteoblastic cell lines in vitro. In this study, we assessed the effects of UD on osteoblastic differentiation in nontransformed osteoblastic cells (MC3T3-E1) and rat bone marrow cells. UD enhanced alkaline phosphatase (ALP) activity and mineralization in a dose- and time-dependent fashion. This stimulatory effect of the UD was observed at relatively low doses (significant at 5–50 μg/ml and maximal at 50 μg/ml). Northern blot analysis showed that UD (100 μg/ml) increases in bone morphogenic protein-2 as well as ALP mRNA concentrations in MC3T3-E1 cells. UD slightly increased in type I collagen mRNA abundance throughout the culture period, whereas it markedly inhibited the gene expression of collagenase-1 between days 15 and 20 of culture. These results indicate that UD has anabolic effects on bone through the promotion of osteoblastic differentiation, suggesting that is could be used for the treatment of common metabolic bone diseases such as osteoporosis.     

Photosynthetic Responses of a Temperate Liana to Xylella fastidiosa Infection and Water Stress

Xylella fastidiosa is a xylem‐limited bacterial plant pathogen that causes bacterial leaf scorch in its hosts. Our previous work showed that water stress enhances leaf scorch symptom severity and progression along the stem of a liana, Parthenocissus quinquefolia, infected by X. fastidiosa. This paper explores the photosynthetic gas exchange responses of P. quinquefolia, with the aim to elucidate mechanisms behind disease expression and its interaction with water stress. We used a 2 × 2‐complete factorial design, repeated over two growing seasons, with high and low soil moisture levels and infected and non‐infected plants. In both years, low soil moisture levels reduced leaf water potentials, net photosynthesis and stomatal conductance at all leaf positions, while X. fastidiosa‐infection reduced these parameters at basally located leaves only. Intercellular CO₂ concentrations were reduced in apical leaves, but increased at the most basal leaf location, implicating a non‐stomatal reduction of photosynthesis in leaves showing the greatest disease development. This result was supported by measured reductions in photosynthetic rates of basal leaves at high CO₂ concentrations, where stomatal limitation was eliminated. Repeated measurements over the summer of 2000 showed that the effects of water stress and infection were progressive over time, reaching their greatest extent in September. By reducing stomatal conductances at moderate levels of water stress, P. quinquefolia maintained relatively high leaf water potentials and delayed the onset of photosynthetic damage due to pathogen and drought‐induced water stress. In addition, chlorophyll fluorescence measurements showed that P. quinquefolia has an efficient means of dissipating excess light energy that protects the photosynthetic machinery of leaves from irreversible photoinhibitory damage that may occur during stress‐induced stomatal limitation of photosynthesis. However, severe stress induced by disease and drought eventually led to non‐stomatal decreases in photosynthesis associated with leaf senescence.     

Structural and immunocytochemical characterization of the adhesive tendril of Virginia creeper (Parthenocissus quinquefolia [L.] Planch.)

Summary. The tendrils of Virginia creeper (Parthenocissus quinquefolia) do not coil around their supports. Rather, they adhere to supporting objects by flattening against the support surface and secreting an adhesive compound which firmly glues the tendril to the support. In this study, microscopic and immunocytochemical techniques were utilized to determine the nature of this adhesive. Following touch stimulation, epidermal cells of the tendril elongate toward the support substrate, becoming papillate in morphology. Following contact with the support surface, an adhesive is produced at the base of the papillate cells. The adhesive appears as a highly heterogeneous, raftlike structure and consists of pectinaceous, rhamnogalacturonan (RG) I-reactive components surrounding a callosic core. In addition, more mobile components, composed of arabinogalactans and mucilaginous pectins, intercalate both the support and the tendril, penetrating the tendril to the proximal ends of the papillate cells. Following adherence to the support, the anticlinal walls of the papillate cells are devoid of RG I side-chain reactivity, indicating that extensive debranching of RG I molecules has taken place. Furthermore, a large amount of RG I backbone reactivity was observed in the contact area. These results may indicate that the debranched RG I molecules diffuse into and permeate the contact region, forming an integral part of the adhesive compound. These results indicate that Virginia creeper adheres to objects by a composite adhesive structure consisting of debranched RG I, callose, and other, less-well characterized mucilaginous pectins and that this structure subsequently becomes lignified and very weather-resistant upon the ultimate senescence of the tendril. Correspondence: Kevin C. Vaughn, USDA-ARS-SWSRU, P.O. Box 350, Stoneville, MS 38776, U.S.A.     

供氮水平对爬山虎(Parthenocissus tricuspidata Planch)生物量及养分分配的影响

爬山虎是典型的亚热带木本攀援植物,在垂直绿化、植被恢复和水土保持等方面的应用日益普遍,而营养元素对爬山虎生长的影响还缺乏研究,这不利于爬山虎的生长调控与合理应用。通过水培试验,对不同氮素水平(0、0.15、0.3、0.45、0.6、0.75g.L-1)条件下爬山虎幼苗生长、氮磷钾营养分配和利用状况作了研究。结果表明:供氮水平的提高能显著促进植株的生物量增加,并影响茎叶的生物量分配比例,供氮处理的叶生物量占总生物量的50%以上;供氮水平的提高能增加植株根、茎、叶的氮含量,对磷含量影响不显著,对茎叶中的钾含量有一定的稀释作用;叶片是主要的氮养分贮存器官,叶片氮累积量达到整个植株总氮累积量的60%以上;供氮水平的增加,降低了爬山虎的氮利用率,提高了磷钾的利用率。