不同生境中桂花和夹竹桃叶际细菌的群落结构

植物叶际微生物多样性是目前植物-微生物关系研究的热点之一,但影响叶际微生物群落结构的主要因素目前还存在很大争议.本研究以生长在3处生境的桂花和夹竹桃为对象,基于高通量测序技术,分析2种植物叶际细菌的群落结构,探讨影响植物叶际细菌群落结构的主要因素.结果表明:来自3处生境的2种植物叶际细菌多样性无显著差异,构成叶际细菌群落的优势门主要包括放线菌门、拟杆菌门、衣原体门、蓝细菌门、厚壁菌门和变形菌门,优势属主要包括甲基杆菌属、鞘氨醇单胞菌属、薄层杆属、Polaromonas和无毛螺旋体属.植物种类、生境及二者的交互作用均能显著影响叶际细菌群落结构,其中生境的影响最大.     

Chemical Constituents and Activities of the Essential Oil from Myristica fragrans against Cigarette Beetle Lasioderma serricorne

Essential oil extracted from nutmeg seeds (Myristica fragrans Houtt .) by hydrodistillation was subjected to GC/MS and GC analysis. A total of 27 constituents were identified, of which eugenol (19.9%), methylisoeugenol (16.8%), methyleugenol (16.7%), sabinene (11.8%), and terpinen‐4‐ol (8.5%) were the major components. The essential oil was tested against Lasioderma serricorne for insecticidal and repellent activity, the LD₅₀ value at the end of 24 h exposure period was 19.3 μg/adult. Six active compounds were isolated by bioassay‐guided fractionation. They were identified as eugenol ( 1 ), methyleugenol ( 2 ), methylisoeugenol ( 3 ), elemicin ( 4 ), myristicin ( 5 ), and safrole ( 6 ). Among these isolates, 4 showed the strongest contact toxicity against L. serricorne adults with an LD₅₀ value of 9.8 μg/adult. Repellency of crude oil and active compounds were also determined. Compounds 1, 2, 4 , and 5 were strongly repellent against the cigarette beetle and exhibited the same level of repellency compared with the positive control, DEET. The results indicate that the essential oil of M. fragrans and its active constituents have potential for development as natural insecticides and repellents to control L. serricorne.     

也门铁的组织培养技术研究

以4品种也门铁的茎段为外植体进行组织培养技术研究。结果表明,控制普通也门铁茎段褐化效果最理想的培养基为MS + 0.25 g·L-1 VC + 0.50 g·L-1 Na2S2O3;诱导也门铁不定芽萌动的最佳培养基为MS + 3.0 mg·L-1 6-BA + 0.2 mg·L-1 NAA + 0.1 mg·L-1 KT;诱导也门铁不定芽增殖的最佳培养基,因品种不同而异,普通也门铁和金心也门铁为MS + 2.0 mg·L-1 6-BA + 1.0 mg·L-1 NAA + 0.1 mg·L-1 GA3,扭纹铁和金心扭纹铁为MS + 1.0 mg·L-1 6-BA + 0.5 mg·L-1 NAA + 0.1 mg·L-1 GA3;也门铁壮苗的最佳培养基为MS + 0.05 mg·L-1 6-BA + 0.05 mg·L-1 NAA + l g·L-1AC;也门铁生根最优培养基为1/2MS + 0.5 mg·L-1 IBA。     

不同光环境下桂花幼苗的构型差异

通过对不同光照条件下桂花幼苗的冠形、分枝率、叶片在树冠中的空间分布等特征进行研究,结果表明桂花幼苗构型发生了明显的可塑性适应:其树冠对光照条件的变化有显著的可塑性响应。在林隙中的幼苗受光的间歇性影响,总体分枝率明显小于全光、林冠下的幼苗分枝率。全光的幼苗叶片集中于二级枝,叶片长度和叶片面积相对较小,对光照利用充分;而林隙中的幼苗叶片集中于一级枝,避免处于植冠内侧受到遮蔽,表现出较大的叶片长度和叶面积;林冠下的叶片较均匀分布在一、二级枝上,叶片总数量较少,枝条高生长较全光下明显。幼苗在总体分枝格局中表现出独自的特点,即强光环境下产生短枝和高分枝率,在适度庇荫条件下产生长枝及低分枝率,在强度庇荫条件下以较长枝和较高分枝率来同时满足高生长和横向生长的需求。     

RAPD技术与桂花品种分类和鉴定

简介了随机扩增多态ＤＮＡ（ＲＡＰＤ）技术的原理,及对桂花品种分类鉴定的必要性,并建议开展ＲＡＰＤ技术在桂花品种分类鉴定的应用研究。     

Preparative isolation and purification of dicaffeoylquinic acids from the Ainsliaea fragrans champ by high-speed counter-current chromatography

Two dicaffeoylquinic acids, namely 3,5-dicaffeoylquinic acid and 4,5-dicaffeoylquinic acid, have been successfully separated by high-speed counter-current chromatography (HSCCC) from an extract of Ainsliaea fragrans Champ, followed by an initial clean-up step using AB-8 resin. A two-phase solvent system composed of chloroform:methanol:water (8:8:4) was selected for the isolation with the aqueous-rich phase as the stationary phase and the organic-rich phase as the mobile phase. The developed HSCCC method yielded 34 mg of 3,5-dicaffeoylquinic acid and 17 mg of 4,5-dicaffeoylquinic acid from 150 mg of the crude sample in a one-step separation with purities of 98 and 95%, respectively, as determined by HPLC. The structures of the two compounds were identified from ESI/MS, (1)H- and (13)C-NMR spectroscopic data.     

香鳞毛蕨配子体发育的研究

研究了香鳞毛蕨(Dryopteris fragrans (L.)Schott)配子体的发育过程。结果发现孢子极面观为椭圆形,赤道面观为半圆形,单裂缝。孢子萌发为书带蕨型;丝状体2～9个细胞长,有明显顶端细胞,可形成多细胞的广阔板状片状体;片状体顶端分生组织继续分裂,发育为幼原叶体;原叶体发育为三叉蕨型;毛状体数量丰富,均为单细胞;颈卵器和精子器几乎同时形成,较小;成熟原叶体倒卵状心脏形。该配子体表现为进化性状。     

影响四季桂插穗生根若干因子研究

本文研究扦插基质、插穗枝梢成熟度和插穗留叶量对四季桂生根的影响。结果表明:枝梢成熟度和扦插基质对插穗生根有显著影响,留1片叶和留2片叶对插穗生根没有显著影响。因此,四季桂扦插宜选用半木质化成熟枝梢,并采用2/3泥炭土+1/3珍珠岩作为扦插基质,留1～2片叶效果最好。