9种榆科植物叶表皮结构特征研究

利用叶表皮离析法观察了榆科6属9种植物叶片的表皮结构。结果表明,榆科植物叶片气孔器仅分布在远轴面,不规则型,不具副卫细胞;叶片毛状体主要有腺毛和非腺毛两种类型,腺毛由基细胞、柄细胞和膨大的顶细胞构成,非腺毛均由单细胞发育而来,基部具或不具钟乳体,多数非腺毛顶部发育成长锥状,少数非腺毛顶部极短呈喙状。根据气孔器的类型和分布位置,尤其是表皮毛的基本结构和发育类型等特征,不支持将广义榆科分为两个独立科的观点。但榆科这9种植物叶表皮特征具有属间或种间差异,有一定的分类学价值。     

植物萜类生物合成与抗虫反应

植物次生代谢在植物的环境适应,尤其是与微生物和动物的互作和防御反应中起重要作用。萜类是植物次生代谢物中最丰富的一类化合物,许多成分具有重要生理功能和应用价值。腺毛和腺体是植物次生代谢物合成、储藏和分泌的重要器官。我们实验室在植物倍半萜和单萜的生物合成途径及其调控机制、表皮毛发育与萜类代谢调控等方面取得了一系列研究进展。此外,还分析了棉铃虫对棉酚的耐受性(适应性)反应,利用棉铃虫防御基因,发展了一种植物介导的RNAi抗虫技术,可以有效、特异地抑制昆虫基因的表达,在植物抗虫技术研究领域有应用前景。     

龙葵腺毛发育的细胞学研究

利用光学显微镜、扫描电镜和透射电镜技术,观察了龙葵“四叶一心”期时叶片及茎表皮的腺毛的种类、分布,探究了不同类型腺毛的起源、生长、成熟、分泌、衰老等发育过程的细胞学特征;通过组织化学染色和荧光显微技术,观察了龙葵腺毛成分、分布,为龙葵的进一步开发利用提供参考。结果表明：（1）龙葵腺毛分为单细胞头腺毛和多细胞头腺毛两类,前者主要分布于茎表面和叶上下表皮,后者主要分布于茎表面的单细胞头腺毛之间、叶脉及叶边缘;（2）龙葵腺毛发育起始于表皮细胞突起,单细胞头腺毛行顶端生长,具1-4个柄细胞,四种类型;多细胞头腺毛可再分为一层、两层与三层多细胞头腺毛,另具三种特殊类型;（3）龙葵成熟腺毛具分泌能力,通过皮下空间的物质积累导致腺毛头细胞表面形成突起、包块、破口,最终释放分泌物;而头细胞与柄细胞随即皱缩、衰老。（4）超微结构显示,腺毛头细胞中内质网与高尔基体极为丰富,合成代谢及分泌活动活跃,产生大量包裹嗜锇物质的囊泡,囊泡与细胞壁融合,进而将嗜锇物质转移至细胞壁并积累,随后储存在角质层下的皮下空间直至分泌释放;（5）组织化学染色结果表明,腺毛含有萜类、生物碱、脂类、蛋白质、酚类和多糖。头细胞中主要含有萜类、生物碱、脂类、蛋白质、酚类和中性多糖;柄细胞中主要含有萜类、生物碱、脂类。     

菱的腺毛发育及分泌活动的超微结构研究

菱的腺毛由单列圆筒状细胞组成,具有短暂的分泌功能。它们起源于叶片远轴面、叶柄的表皮细胞以及苗端茎轴、花柄的表皮细胞。处于分泌期的腺毛细胞其胞质浓厚,液泡化程度小,细胞具丰富的线粒体、高尔基体。腺毛丧失了分泌功能后即发育成为表皮毛。粘液物质由高尔基体分泌小泡携带至腺毛细胞侧壁,经胞吐与渗透结合的方式分泌至细胞外,粘液的化学成分主要为多糖。     

线纹香茶菜叶上腺毛发育的细胞学研究

为进行中药溪黄草基原植物的品种鉴定,采用光镜和电镜对线纹香茶菜(原变种)[Isodon lophanthoides var.lophanthoides]叶上腺毛的发育进行细胞学研究。结果表明,线纹香茶菜具有头状腺毛和盾状腺毛2种类型。头状腺毛无色透明,由1个基细胞、1个柄细胞和1或2个头部分泌细胞构成;盾状腺毛为红色,由1或2个基细胞、1个柄细胞和4~8个分泌细胞构成头部。2种腺毛均由原表皮细胞经两次平周分裂形成,后因柄细胞和头部细胞所处的分化状态不同而形成两类腺毛。2种腺毛超微结构表明,质体、高尔基体和粗面内质网为主要分泌物产生和运输的细胞器。当盾状腺毛成熟时,角质层下间隙充满了分泌物,其分泌物的性质很可能决定了线纹香茶菜腺毛的颜色。     

荇菜腺毛的发育及其分泌过程的超微结构研究

荇菜 (Nymphoides peltatum (Gmel.) O.Kuntz)腺毛由具分泌功能的单列圆筒状细胞组成。它们起源于苗端倒数第二叶原基近轴面 ,由原表皮细胞发育而来。处于分泌期的腺毛细胞其胞质浓厚 ,液泡化程度小。细胞内具丰富的线粒体、高尔基体和内质网等细胞器 ,还具发达的胞间连丝。粘液物质由高尔基体分泌小泡、内质网分泌小泡及多膜体共同携带至细胞边缘 ,经胞吐和渗透相结合的方式分泌至细胞外。腺毛细胞侧壁因积有大量分泌物而呈膨胀状态。经检测 ,粘液由多糖和蛋白质组成 ,对营养芽的生长发育起保护作用。     

植物防御素基因家族结构、功能及调控研究进展

防御素(Defensins,DF)是抗菌肽家族中最古老的一员。植物防御素是一类包含45-54个氨基酸残基,含有半胱氨酸(Cys)稳定的αβ模序,与哺乳动物及昆虫抗菌肽的亲缘关系非常密切,大部分植物防御素在体内被合成为具有信号肽序列的前体,并被分泌到胞外空间。植物防御素在宿主防御系统中起重要作用,不仅可抑制一系列的植物、动物及人类体内的细菌、真菌,还可杀伤一些肿瘤细胞及病原虫。植物防御素广泛存在于植物的花、茎、叶、果实、根和种子中,具有抗菌、抗肿瘤、抑制酶活、作为离子阻断剂和增加耐受性的功能,可作为新型的杀菌剂或新型的抗生素类药物。随着抗生素导致的耐药菌株的出现,对植物防御素的研究就显得尤为重要,特别是因其有效的抗真菌活性,植物防御素在作物抗病基因工程方面具有巨大的潜力。主要介绍了其发现、结构、类型、逆境调控功能、作用机制以及外源表达植物防御素基因等方面的最新研究进展,有助于将来对植物防御素基因家族进行更深入和全面的研究。     

羽叶薰衣草表皮毛的发育解剖学研究

对羽叶薰衣草(LavandulapinnataL.)茎和叶上两种表皮毛(腺毛和非腺毛)发育的解剖学观察表明,两者的发生都源于茎或叶的原表皮细胞,但外部形态、发育过程及功能明显不同。腺毛有头状腺毛和盾状腺毛两种类型,均由1个基细胞、1个柄细胞和头部细胞构成。头状腺毛的头部只有1个或2个分泌细胞,盾状腺毛由8个分泌细胞构成头部。非腺毛由3-20个细胞组成,可分为三种类型:单列不分枝、二叉分枝和三叉及三叉以上多分枝的树状分枝。非腺毛的顶部细胞由基部到顶部逐渐变细,先端成尖形。腺毛发育由原表皮细胞经两次平周分裂形成,由于柄细胞和头部细胞所处的分化状态不同而发育成两类腺毛。非腺毛由非腺毛原始细胞经二次或多次平周分裂和不均等分裂,再发育成数个至二十多个子细胞。     

植物不同类型表皮毛调控模型研究进展

表皮毛是植物地上部分表皮细胞向外突出延伸的特化毛状结构,不仅可以保护植物免受病虫的危害,还具有一定的经济和药用价值,对其调控的分子机制的阐明有利于植物的分子设计育种和遗传改良。近年来,模式植物拟南芥表皮毛形成的调控模式基本被阐明,其他植物表皮毛的调控机制也取得很大进展。鉴于此,文中综述了拟南芥和棉花(单细胞表皮毛)及番茄和青蒿(多细胞表皮毛)在基因和激素水平上对表皮毛的发育调控,同时简要介绍了其他典型单、双子叶植物表皮毛相关的研究进展,最后,展望了植物表皮毛的研究方向和应用前景。     

唇形科植物腺毛及其分泌研究进展

唇形科植物的茎和叶通常着生腺毛,能分泌芳香油,腺毛的分布密度越大其分泌能力越强。对近年来该科植物腺毛及其分泌的研究进展作一综述,对腺毛的结构类型、发生发育和分泌物及其分泌过程作了介绍,指出了该研究领域中存在的问题。     

Isolation and Analysis of Differential Expressed ESTs from Stem Trichomes of Lycopersicon esculentum (Solanaceae)

Glandular trichomes are special organs involved in plant defense response and synthesis of volatile secondary metabolites, analyzing trichome specific expressed sequence tags will help us further understand the specific function of plant trichomes. In this paper, suppression subtractive hybridization（SSH） based on magnetic beads technology was used to isolate differential expressed genes of the glandular trichomes in Lycopersicon esculentum. The differential expressing cDNA library was constructed using the glandular trichomes cDNA as tester and the cDNA from the stem without glandular trichomes as driver. After randomly sequencing 108 differential ESTs, Blast2go program was used to do blastx, functional annotation and metabolism analysis. The results show that most ESTs are related to substance metabolism, response to stress, biotic or abiotic stimulus, and have binding and catalytic function. These differential genes lay the foundation for further research on defense mechanism of the tomato trichomes.     

Peltate glandular trichomes of Colquhounia seguinii harbor new defensive clerodane diterpenoids

Glandular trichomes produce a wide variety of secondary metabolites that are considered as major defen-sive chemicals against herbivore attack. The morphology and secondary metabolites of the peltate g...     

番茄茎腺毛差异表达序列分离与分析

腺毛是参与植物防御性反应与次生代谢挥发物合成的特异化器官,了解腺毛专一性表达序列标签将有助于我们进一步认识植物腺毛的特异性功能.本文应用磁珠介导的抑制消减杂交方法(SSH),以番茄茎腺毛为检测子(tester),去除腺毛的番茄茎为驱动子(driver),构建番茄茎腺毛差异表达cDNA文库,分离腺毛差异表达基因.随机挑选了108个差异ESTs进行测序,测序结果使用Blast2go程序进行blastx比对、功能注释和KEGG代谢路径分析.结果表明,绝大部分ESTs功能与胁迫响应、物质代谢、生物及非生物刺激反应相关,具有结合、催化功能.这些分离的差异ESTs为进一步研究番茄腺毛的植物防御性机制奠定了基础.     

Bidirectional Secretions from Glandular Trichomes of Pyrethrum Enable Immunization of Seedlings

Glandular trichomes are currently known only to store mono- and sesquiterpene compounds in the subcuticular cavity just above the apical cells of trichomes or emit them into the headspace. We demonstrate that basipetal secretions can also occur, by addressing the organization of the biosynthesis and storage of pyrethrins in pyrethrum (Tanacetum cinerariifolium) flowers. Pyrethrum produces a diverse array of pyrethrins and sesquiterpene lactones for plant defense. The highest concentrations accumulate in the flower achenes, which are densely covered by glandular trichomes. The trichomes of mature achenes contain sesquiterpene lactones and other secondary metabolites, but no pyrethrins. However, during achene maturation, the key pyrethrin biosynthetic pathway enzyme chrysanthemyl diphosphate synthase is expressed only in glandular trichomes. We show evidence that chrysanthemic acid is translocated from trichomes to pericarp, where it is esterified into pyrethrins that accumulate in intercellular spaces. During seed maturation, pyrethrins are then absorbed by the embryo, and during seed germination, the embryo-stored pyrethrins are recruited by seedling tissues, which, for lack of trichomes, cannot produce pyrethrins themselves. The findings demonstrate that plant glandular trichomes can selectively secrete in a basipetal direction monoterpenoids, which can reach distant tissues, participate in chemical conversions, and immunize seedlings against insects and fungi.     

Harnessing plant trichome biochemistry for the production of useful compounds

Plant trichomes come in a variety of shapes, sizes and cellular composition. Some types, commonly called glandular trichomes, produce large amounts of specialized (secondary) metabolites of diverse classes. Trichomes are implicated in a variety of adaptive processes, including defense against herbivores and micro-organisms as well as in ion homeostasis. Because trichomes protrude from the epidermis and can often be easily separated from it and harvested, the mRNAs, proteins and small molecules that they contain are unusually accessible to analysis. This property makes them excellent experimental systems for identification of the enzymes and pathways responsible for the synthesis of the specialized metabolites found in these structures and sometimes elsewhere in the plant. We review the literature on the biochemistry of trichomes and consider the attributes that might make them highly useful targets for plant metabolic engineering.     

Leaf glandular trichomes in Empetrum nigrum: morphology,histochemistry, ultrastructure and secondary metabolites

The morphology, histochemistry and ultrastructure of the glandular trichomes on Empetrumnigrum leaves have been studied and more than a third of the metabolites were identified. Samples of the leaves were fixed and processed for light and electron microscopy. Glandular trichomes are situated on the inner surface of the rolled leaves. They have a clavate head and a short stalk. Histochemical tests and fluorescent microscopy demonstrate differentiated staining of the various cell types in the glandular trichome for proteins, pectins, lipids, tannins and phenylpropanoids. During secretion, the secretory cells contain rough and smooth endoplasmic reticulum, Golgi stacks with large vesicles, diversiform leucoplasts in contact with a reticular sheath and opaque deposits in the vacuoles. There are ultrastructural and functional differences between the secretory cells in the trichome head: synthesis of hydrophilic substances predominately occurs in the upper and middle secretory cells, whereas synthesis of lipophilic compounds takes place in the middle and lower secretory cells. Gas chromatography–mass spectrometry was used to determine the content of metabolites in the methanol extracts from the leaves. Many phenolic compounds (phenolic acids, bibenzyls, catechins, flavanones and flavan‐3‐ols) as well as several terpenoids were found. Two chalcones (2′,4′‐dimethoxydihydrochalcone and 2′,4′,6′‐trihydroxydihydrochalcone), one bibenzyl (batatasin III), one flavanone (7‐hydroxyflavanone) and 8 terpenoids (including phytol, α‐tocopherol, ß‐sitosterol, α‐amyrin, uvaol, oleanolic acid, ursolic acid and dehydroursolic acid) were identified in E. nigrum leaf extracts. The total yield of phenolic compounds is five to six times higher than the yield of terpenoids. It has been established that chalcones have no hydroxyl groups in ring B whereas bibenzyls have a hydroxyl group in the 3‐position in ring B. On the basis of the histochemistry, fluorescent microscopy, ultrastructure and chemical analysis, it may be concluded that synthesis and accumulation of phenolic substances and terpenoids takes place in the clavate glandular trichomes. Secondary metabolites synthesized in the trichomes protect leaf tissues from viruses, bacteria and pathogenic fungi.     

Petunia hybrida PDR2 is involved in herbivore defense by controlling steroidal contents in trichomes

As a first line of defense against insect herbivores many plants store high concentrations of toxic and deterrent secondary metabolites in glandular trichomes. Plant Pleiotropic Drug Resistance (PDR)‐type ABC transporters are known secondary metabolite transporters, and several have been implicated in pathogen or herbivore defense. Here, we report on Petunia hybrida PhPDR2 as a major contributor to trichome‐related chemical defense. PhPDR2 was found to localize to the plasma membrane and be predominantly expressed in multicellular glandular trichomes of leaves and stems. Down‐regulation of PhPDR2 via RNA interference (pdr2) resulted in a markedly higher susceptibility of the transgenic plants to the generalist foliage feeder Spodoptera littoralis. Untargeted screening of pdr2 trichome metabolite contents showed a significant decrease in petuniasterone and petuniolide content, compounds, which had previously been shown to act as potent toxins against various insects. Our findings suggest that PhPDR2 plays a leading role in controlling petuniasterone levels in leaves and trichomes of petunia, thus contributing to herbivory resistance.