安徽紫薇属(千屈菜科)一新种

描述了安徽产一个新种即安徽紫薇.     

Diurnal variations of amino acids and organic acids in xylem fluid from Lagerstroemia indica: an endogenous circadian rhythm

Diurnal variations in the concentrations of major organic compounds occurred in xylem fluid extracted from Lagerstroemia indica L. The concentration of amino acids and the N/C ratio was at a maximum and that of organic acids was at a minimum between 1230 and 2030 h. Since the concentrations of total organic nitrogen, total amino acids and most individual amino acids (but not organic acids or sugars) were also proportional to xylem tension two experiments were performed to discern whether variations in chemistry were a consequence of diurnal changes in moisture stress. In the first experiment, L. indica , exposed to variable levels of moisture stress during midday, manifested an increase in organic acids and a reduction in the N/C ratio. In the second experiment, chemical profiles of xylem fluid were collected and compared for plants exposed to a natural photoperiod, constant darkness or continuous light at noon and midnight. After 1 day amino acids increased in concentration during midday for all treatments; the variation was greatest (10-fold) for plants in constant darkness where xylem tension varied from 0.20 to 0.25 MPa. Only plants exposed to continuous light lost a diurnal rhythm after 3 days. Thus, the circadian rhythm was endogenous, terminated in continuous light and was not mediated by changes in moisture stress. Glutamine accounted for most of the diurnal variation in total amino acids, organic nitrogen and the N/C ratio in xylem fluid.     

Plant-based corosolic acid: Future anti-diabetic drug?

Diabetes is one of the nation's most prevalent, debilitating and costly diseases. For diabetes, frequent insulin treatment is very expensive and may increase anti-insulin antibody production, which may cause unwanted side effects. Corosolic acid may also have some efficacy in the treatment of diabetes, but without induction of anti-insulin antibodies. Recently, corosolic acid from Lagerstroemia speciosa L. leaf extracts has been reported to act via an indirect mechanism (unlike insulin) in animal experiments. The insulin-complementary anti-diabetic therapeutic value observed in these Japanese preliminary clinical trials has led to renewed interest in the biosynthesis of this compound. So far, there has been no clear evidence for a corosolic acid biosynthetic pathway in plants. This article provides possible roles of corosolic acid and hypothetical information on the biosynthetic pathway in plants.     

Cadmium accumulation and tolerance of Lagerstroemia indica and Lagerstroemia fauriei (Lythraceae) seedlings for phytoremediation applications

Contamination by heavy metals is one of the most serious environmental problems generated from human activities. Because phytoremediation utilizes plants to uptake contaminants, it could potentially be used to remediate metal-contaminated areas. A pot culture experiment with four levels of cadmium (Cd) (0, 20, 40, and 80 mg of Cd/kg dry soil) was conducted to investigate Cd accumulation and tolerance of roots, shoots, and leaves of Lagerstroemia indica and Lagerstroemia fauriei as well as their potential for phytoremediation. Experimental results indicated that Cd inhibited seedling growth only at the higher Cd exposure concentration (40 and 80 mg/kg). The tolerance index revealed that on average L. indica is more tolerant of Cd than L. fauriei. Moreover, plants in the experiment accumulated Cd differentially. In comparisons between L. indica and L. fauriei, the leaves of the former had higher concentrations of Cd, while the roots of latter had higher concentrations of Cd. Furthermore, the roots, shoots, and leaves had very high bioaccumulation factors that markedly exceeded 1.0 (exceptional only in shoots of 80 mg/kg for L. fauriei), indicating that the seedlings extracted Cd from the soil. The leaves' translocation factor of L. indica was greater than 1.0, being significantly higher than that of L. fauriei. Chlorophyll a, Chlorophyll b and total declined in both species significantly as Cd concentrations exceeded 40 mg/kg in the soil. In contrast, lipid peroxidation and proline content was found to increase with increasing Cd concentration. From the assessments of biomass production, Cd tolerance and uptake L. indica and L. fauriei could stand as excellent species for remediating Cd-contaminated soils.     

Stereochemistry of Pyrethrosin,Cyclopyrethrosin Acetate and Isocyclopyrethrosin Acetate

The acid cyclization product from pyrethrosin has been proved to be a (1:1)-mixture of cyclopyrethrosin acetate containing a Δ³⁽⁴⁾-double bond and isocyclopyrethrosin acetate with a Δ⁴⁽¹⁵⁾-double bond through the reinvestigation. NMR and ORD studies on their derivatives led us to assign revised stereochemistry to pyrethrosin and its related compounds.     

N^＋注入对紫薇光合特性和叶绿素含量的影响

采用离子注入诱变育种技术对紫薇种子进行处理,正常播种后测两年生植株叶片的光合特性和叶绿素含量,结果表明：与对照相比,经离子注入处理后,各处理的净光合速率都有不同程度的增加,光合速率饱和时所需要的光合有效辐射均较未注入处理的低。叶绿素a和b的绝对含量呈现双峰型变化趋势,但叶绿素a的增加量受注入剂量的影响较大,叶绿素a/b比值变化不明显,离子注入处理能提高紫薇幼苗的潜在光合能力和耐荫性。     

修剪措施对紫叶紫薇花蕾中内源激素和碳氮营养含量的影响

为探讨修剪措施对二次开花的紫叶紫薇花蕾中内源激素和碳氮营养含量的影响,为指导紫叶紫薇花期调控提供理论依据,该研究以‘丹红紫叶’为试验材料,在一次花的末花期对主花枝进行重度修剪,以不进行修剪为对照(CK),分析不同处理下紫叶紫薇花蕾中主要花发育时期的吲哚乙酸(IAA)、脱落酸(ABA)、赤霉素(GA₃)、玉米素核苷(ZR)、可溶性糖、淀粉、全氮含量的变化。结果表明：(1)修剪处理后,紫叶紫薇花蕾中内源ZR含量在各花发育时期显著升高;内源GA₃含量在花芽分化期降低,在初花期至末花期显著升高;内源IAA含量在花芽分化期显著升高,在初花期至末花期降低;内源ABA含量变化不显著。(2)修剪处理后,紫叶紫薇花蕾可溶性糖含量较对照组先升高后降低,在末花期变化达到显著水平;其淀粉、全氮含量增加但未达到显著水平。(3)紫叶紫薇花蕾中碳氮比总体呈上升趋势,修剪处理后其碳氮比值小幅度提高。研究认为,修剪措施能够影响紫叶紫薇内源激素水平变化,并通过调控碳水化合物与全氮含量影响花蕾中碳氮营养代谢,从而促进了紫叶紫薇二次成花、花期延长。     

Applying the Richards function in freezing tolerance determination with electrolyte and phenolic leakage techniques

The purpose of the present study was to apply the Richards function to fit electrolyte and phenolic leakage data for several taxa of woody plants subjected to freezing stress and to determine how the curve inflection point relates to the lethal temperature range. The lowest survival temperature of Fraxinus americana, Lagerstroemia cv. Natchez, Magnolia grandiflora, Rhododendron cv. Red Ruffle and Zelkova serrata was determined based on visual evaluation of oxidative browning facilitated by a modified regrowth test and differential thermal analysis. Lethal injury occurred in all cases within a range of 3°C below lowest survival temperature. Using the Richards function inflection point as an estimate of lethal temperature led to an overestimation of freezing tolerance in most taxa. This overestimation was greater for stems than leaves, and was greater in winter than in summer. The lethal temperature range generally coincided with the initial increase in leakage caused by freezing. The lethal temperature range also was determined by using a point of interception of the lower asymptote of a curve with a line tangential to the inflection point. In most taxa tested estimated lethal temperature based on the point of interception provided an improvement over the estimate based on the point of inflection.     

紫薇品种表型多样性分析

对111个紫薇品种的17个表型分类性状多样性进行了研究。结果表明,紫薇品种具有丰富的表型多样性,平均遗传多样性指数为0.707。总体上是数量性状形态多样性指数大于质量性状,其中花色、瓣爪色2个质量性状和花径、着花数、花序长、花序宽、种子千粒重5个数量性状变异明显,其多样性指数分别大于1.2和1.4。不同紫薇品种群表型性状多样性差异明显,多样性指数由高到低依次为:红薇品种群(H'=0.838)、堇薇品种群(H'=0.823)、银薇品种群(H'=0.696)、矮生品种群(H'=0.604)、复色品种群(H'=0.573)。通过主成分分析,上述2个质量性状和5个数量性状主成分的贡献率为67.70%,包括花序长、花序宽、着花数、花色数、花色、种子千粒重、瓣爪色、叶色、小枝四棱、花香、花径等11个形态性状指标,代表了紫薇品种表型分类性状的综合特征。基于表型形态性状,111个紫薇品种可聚类为5大类群,其遗传聚类与花色及株型关系密切,4个以花色为主要分类性状的品种群总体演化趋势是:堇薇品种群→红薇品种群→银薇品种群→复色品种群。