灯盏花大小孢子形成与胚胎发育

用石蜡切片法对灯盏花从花原基分化到胚胎形成的全过程进行系统观察,结果表明:灯盏花从初孕花序至头状花序的直径(d)在2.8～3.1 mm时为花器官分化期,包括花原基分化期、花萼与花冠分化期、雌雄蕊分化期以及分化完成期4个阶段;灯盏花花药4室,药壁发育属双子叶型,绒毡层细胞属于变形绒毡层;小孢子母细胞减数分裂为同时型,成熟花粉为3-细胞型;子房下位,1室,单珠被,薄珠心,胚珠倒生,胚囊发育为蓼型;珠孔受精,属于有丝分裂前类型,胚乳发育为细胞型,胚胎发育应属紫菀型.     

黄瓜花性别分化和内源激素的关系

黄瓜雌花中GA3 和IAA含量均高于雄花 ;雌花在大孢子母细胞时期以后直到发育成熟 ,IAA含量持续增加 ,雄花中IAA含量则下降 ;ZT含量增加有利于大小孢子母细胞的形成而ABA含量增加则有利于四分体的形成。高水平的ZT/IAA和低水平的GA3 /ZT有利于大孢子母细胞和花粉粒的形成 ,大孢子四分体在高水平的GA3 /ZT和低水平的ZT/IAA下形成。雌性系黄瓜经硝酸银处理后茎尖中GA3 增加、IAA和ZT减少 ,有利于雄性分化 ;强雄性系黄瓜经乙烯利处理后 ,茎尖中GA3 下降 ,IAA和ZT增加 ,有利于雌性分化。据此认为内源IAA可能是黄瓜性别发育的关键性激素     

黄瓜花性别分化与内源多胺的关系

研究了黄瓜雌、雄花几个主要发育时期和性别逆转过程中内源多胺的变化。结果表明 ,雄花在不同发育时期 ,内源腐胺含量均高于雌花 ,腐胺含量的显著升高伴随着花粉粒的形成 ,高腐胺含量是雄花发育的特征。雌花在大孢子母细胞时期以后直到雌花发育成熟 ,其内源尸胺含量均高于雄花 ,高尸胺含量可能有利于雌花的发育。高水平的内源多胺、精胺和亚精胺可能有利于雌花大孢子母细胞的形成。亚精胺和腐胺含量随着大小孢子四分体形成和大孢子核的连续分裂而分别表现下降和上升。雌性系黄瓜经硝酸银诱导雄花处理后 ,茎尖内源亚精胺含量下降 ,腐胺含量上升 ,从而诱导雄花形成 ;雄性系黄瓜经乙烯利诱导雌花处理后 ,茎尖内源亚精胺含量上升 ,腐胺含量下降 ,从而诱导雌花形成     

宽叶泽苔草的花器官发生

通过扫描电镜观察了宽叶泽苔草Caldesia grandisSamuel.的花器官发生。宽叶泽苔草 的萼片3枚,逆时针螺旋向心发生 ;花瓣3枚,呈一轮近同时发生,未观察到花瓣_雄蕊复合原基;雄蕊、心皮原基皆轮状向心 发生,最先近同时发生的6枚原基全部发育成雄蕊,随后发生的6枚原基早期并无差别,在发 育过程中逐渐出现形态差异,直至其中1－4枚发育成心皮,其余的发育成雄蕊;而后的几轮 心皮原基,6枚一轮,陆续向心相间发生。本文揭示了3枚萼片螺旋状的发生方式,并推测这种螺旋方式是泽泻科植物进化过程中保留下来     

黄瓜花原基的形成及与Ca~(2+)的关系

以黄瓜为试验材料研究了肉眼可见的花原基突起之前 ,花原基早期的分化过程。结果显示花原基分化和开花的起始节位是第一真叶节 ;肉眼可见花原基突起前早期的分化是在叶腋亚表皮部位形成一个球形的花原基起始细胞团 ,此细胞团进一步分裂、扩大形成肉眼可见的花原基突起 ;第一真叶节的花原基起始细胞团分化集中发生于 6～ 7d苗龄时期 ;Ca2 + 在花原基起始细胞团细胞中主要分布在细胞壁和细胞间隙 ,而在非起始细胞团的叶腋亚表皮细胞则主要分布在液泡中 ,并对Ca2 + 在花原基起始细胞团分化中的作用进行了讨论。     

花生叶片离体培养花器官分化及其开花结果研究

以花生幼叶为外植体进行离体培养,研究BA浓度对花器官分化的影响并进一步观察试管内花器官的发育.结果表明:经MSB 1mg/LBA 0.5mg/LKIN 2mg/LIAA培养基诱导的愈伤组织,转接到附加1～3mg/LBA的MSB培养基上培养,均能直接诱导分化花器官,但2mg/LBA的诱导效率最高达21.13%;诱导分化的花器官转接到MSB培养基继续培养,部分花器官可以在试管内开花、受精、成针、结实.试验实现了以花生幼叶为外植体,在试管内完成诱导花芽、开花、受精、形成果针、子房膨大,直至形成荚果等过程,为离体条件下研究花生花器官分化、荚果及种子发育提供了技术体系和材料.     

花叶芋(天南星科)的花器官发生

利用扫描电镜首次观察了天南星科花叶芋(Colocasia bicolor) 的花器官发生过程。花叶芋的肉穗花序由无花被的单性花构成, 雌花发生于花序基部, 雄花发生于花序上部, 中性花位于花序中间部位。雄花: 3 或4 个初生雄蕊原基轮状发生, 随后每个初生原基一分为二, 形成6或8个次生原基; 一部分次生原基在其后的发育过程中融合, 形成5 或7 枚雄蕊; 雄花发育过程中未见雌性结构的分化; 花药的分化先于花丝; 雄蕊合生成雄蕊柱。雌花: 合生心皮, 3或4个心皮原基轮状发生, 未见雄性结构的分化。中性花来源于雌雄花序过渡带上, 属于雄蕊原基的滞后发育以及发育成熟过程中的退化; 与彩叶芋属(Caladium)不同, 此过渡区未见畸形两性花。初生雄蕊原基二裂产生次生原基的次生现象在目前天南星科花器官发生中显得比较特殊, 同时初步探讨了次生原基的融合方式。     

太原黄耆(豆科)花器官及胚珠发育研究

太原黄耆是新近发表的物种,分布于中国陕西和山西。该实验利用扫描电子显微镜对太原黄耆的花器官发生和发育过程进行观察研究。结果显示:(1)太原黄耆的各轮花器官都是从远轴端向近轴端单向连续发生,在不同轮之间存在花器官重叠发生的现象。(2)在花的发育过程中,出现2种共同原基,即初级共同原基和次级共同原基,由初级共同原基发育成对萼雄蕊原基和次级共同原基,再由次级共同原基发育成花瓣原基和对瓣雄蕊原基。(3)雄蕊管近轴端基部开口是在进化过程中产生的特殊结构,是一种对传粉者的适应机制,从而有利于传粉活动的进行。(4)胚珠为倒生胚珠,具有2层珠被,认为倒生胚珠是内外2层珠被共同作用的结果。     

臭椿化学成分的初步研究

从国产臭椿木材中分到三种化学成分,经元素和光谱(IR,UV,NMR,MS)分析鉴定为B-谷甾醇,Canthin-6-one和1-methoxycanthin-6-one。     

黄瓜花原基的形成及与Ca^2＋的关系

以黄瓜为试验材料研究了肉眼可见的花原基突起之前,花原基早期的分化过程。结果显示花原基分化和开花的起始节位是第一真叶节;肉眼可见花原基突起前早期的分化是在叶腋亚表皮部位形成一个球形的花原基起始细胞团,此细胞团进一步分裂、扩大形成肉眼可见的花原基突起;第一真叶节的花原基起始细胞团分化集中发生于6—7d苗龄时期;Ca^2 在花原基起始细胞团细胞中主要分布在细胞壁和细胞间隙,而在非起始细胞团的叶腋亚表皮细胞则主要分布在液泡中,并对Ca^2 在花原基起始细胞团分化中的作用进行了讨论。     

Phylogeography of the widespread plant Ailanthus altissima (Simaroubaceae) in China indicated by three chloroplast DNA regions

Ailanthus altissima (Mill.) Swingle, a temperate tree species, has a wide distribution in China. To infer its refugia and patterns of migration during past climatic changes in China, genetic variations among different populations were studied. Gene sequences of three chloroplast DNA spacer regions, psbA-trnH, trnL-trnF, andtrnD-trnT, were obtained from 440 individuals of 44 populations. The distribution of haplotype and the relationships among them were investigated by haplotype network. In addition, the genetic diversity of the sampled regions was inferred, and the biogeographic history was also reconstructed. Twelve haplotypes were identified, among which, five were unique. The phylogenetic analysis and geographical distribution of haplotypes indicate that multiple glacial refugia existed in mainland China during the Quaternary oscillations. Due to the combined effects of contiguous range expansion and allopatric fragmentation, significant genetic structure was not found in this study. Based on biogeographic and demographic analysis, three main dispersal routes were identified for the major haplotypes, whereas others were more likely localized demographic expansion.     

Identification of an allelopathic compound from Ailanthus altissima (Simaroubaceae) and characterization of its herbicidal activity

Aqueous extracts of Ailanthus altissima bark and foliage were previously shown to be toxic to other plants. Using bioassay-directed fractionation, I isolated the phytotoxic compound from A. altissima root bark and identified it to be ailanthone, a quassinoid compound having molecular mass of 376. Ailanthone was highly phytotoxic, with concentrations of 0.7 ml/L causing 50% inhibition of radicle elongation in a standardized bioassay with garden cress (Lepidium sativum) seeds. Ailanthone exhibited potent pre- and postemergence herbicidal activity in greenhouse trials. Postcmergence activity was especially striking; even the lowest application rate (0.5 kg/ha) caused complete mortality of five of the seven plant species tested within 5 d of treatment. In contrast, the highest application rate (8 kg/ha) did not cause any detectable injury to A. altissima seedlings, indicating the presence of a protective mechanism in the producer species to prevent autotoxicity. Ailanthone was rapidly detoxified in field soil as a result of microbial activity. Applications of ailanthone equivalent to 0.5 and 4.0 kg/ha completely lost their phytotoxicity within ≤5 d when incubated in the presence of nonsterile soil. When incubated with sterile soil under identical conditions, however, ailanthone remained highly phytotoxic throughout the 21-d duration of the investigation. The high level of postemergence herbicidal activity in conjunction with its rapid biodegradation in soil suggest ailanthone may have potential for development as a natural-product herbicide.     

Microsatellites for tree of heaven (Ailanthus altissima)

Nine (CT)_n microsatellites were developed for tree of heaven, Ailanthus altissima, from invasive populations on the Mediterranean islands. These loci had seven to 12 alleles in 96 trees from five islands. Two loci had significant deficits of heterozygotes within islands while the other loci were in Hardy–Weinberg equilibrium, and four pairs of loci had significant linkage disequilibrium within a single island. These loci were also polymorphic in one to three individuals of the tree of heaven varieties, Ailanthus altissima erythrocarpa, Ailanthus altissima sutchuenensis and Ailanthus altissima tanakai, and the related species Ailanthus giraldii and Ailanthus vilmariniana.     

臭椿不同发育阶段叶片表面结构特征

利用光学显微镜和扫描电子显微镜技术,对臭椿(Ailanthus altissima(Mill.)Swingle)叶片从叶芽到成熟叶4个发育阶段(叶芽、幼叶、近成熟叶和成熟叶)的4种叶表面结构(表皮毛、气孔器、角质层、腺体)进行了详细地观察和比较。结果显示:叶片上、下表面具单细胞非腺毛和头状腺毛两种表皮毛,其密度在叶芽阶段最大,之后随着叶片的生长和展开表皮毛密度逐渐降低;气孔器主要分布于下表面,叶片近成熟时气孔器密度最大;角质层具有条纹状结构,其隆起程度在近成熟叶阶段达到最大;叶片基部两侧具锯齿状突起,每个突起上有一个腺体,腺体发育成熟后可分泌透明黏液。说明叶片表面各结构特征是臭椿对环境长期适应的结果。     

臭椿种子萌发最适条件研究

采用不同浓度赤霉素(GA3)处理臭椿种子,在不同温度及不同光照条件下,研究了GA3、温度及光照对臭椿种子萌发的影响。结果表明,40 mg.L-1的GA3质量浓度、30℃温度以及自然光暗交替处理为臭椿种子萌发的最适条件,臭椿属于喜高温型种子。     

臭椿茎中分泌道的发育及其组织化学研究

利用植物解剖学方法研究臭椿茎和叶柄中分泌道的结构、分布和发育过程.结果表明:臭椿茎和叶柄中的分泌道分布于髓的周缘,次生木质部中无分泌道.分泌道是由一层分泌细胞围绕分泌腔而构成,分泌细胞外有1～2层鞘细胞.分泌道以裂生方式形成,其发育过程可分为3个阶段:原始细胞阶段、形成阶段和成熟阶段.在原始细胞阶段,一群原始细胞具浓厚细胞质,细胞核清晰可见;形成阶段,原始细胞的中央细胞间细胞壁中层降解,细胞壁分离,形成腔隙,随着分泌细胞数量的增加,分泌腔体积扩大;成熟阶段的分泌道具有12～16个分泌细胞,1～2层鞘细胞,分泌腔直径为30～50μm.组织化学研究表明,分泌细胞及分泌道内含物中含大量的萜类、多糖和脂类物质.机械创伤能够诱导次生木质部中产生创伤分泌道.臭椿茎中的分泌道和创伤性分泌道在抵御生物和非生物胁迫中起重要作用.     

Estimating wind dispersal potential in Ailanthus altissima: The need to consider the three-dimensional structure of samaras

Plant dispersal is a very important ecological phenomenon, as it can enable species to move away from the parent plant. This contributes to shaping communities, determining patterns of distribution, landscape configuration, plant invasions and evolutionary processes. Measuring dispersal distance directly is difficult and thus, diaspore morphology can be used to make estimates. Previous research on the topic often resorts to analysing the diaspore’s morphology as if it was a bi-dimensional structure; when in many cases, diaspores have three-dimensional qualities. In this study, we show how estimates of wind dispersal potential of Ailanthus altissima can be considerably improved using morphological variables that succeed in describing the three-dimensional nature of samaras. We suggest that this reasoning could be extensively applied to research involving not only other species, but also multi-specific scenarios with a wide range of diaspore morphologies.     

Occurrence and development of Eucryptorrhynchus brandti and E. chinensis (Coleoptera: Curculionidae) on Ailanthus altissima trees subjected to different levels of mechanical damage

Eucryptorrhynchus brandti (Harold) and E. chinensis (Oliver) are herbivores of Ailanthus altissima (Mill.) Swingle (tree of heaven) in China. Eucryptorrhynchus brandti has been recommended as a potential biological control agent of A. altissima in North America. In China, the majority of adults of both species were found on tree trunks 0–5 m above the ground, from May to September. In October and November, most adults were found at the base of A. altissima trees. Trees were subjected to different levels of mechanical injury: very low mechanical injury, one to two 0.015 m² bark sections were removed; low, two to four bark sections were removed; moderate, 8 to 22 bark sections removed; high, tree was girdled; and extreme, tree was felled and the remaining stump was sampled. Very low and low mechanical injury trees had very few adult emergence holes with few larvae developing beyond the first or second instar after 29 months. The health of these trees remained good. An increase in adult emergence holes occurred in moderately injured trees that appeared as healthy as very low to low mechanically injured trees. This may indicate that only a small increase in tree stress can increase the adult emergence rate and thus hasten a decline in tree health. Moderate, high and extreme mechanically injured trees had significantly more emergence holes/m than very low and low injured trees and late larval stages were present. The development of Eucryptorrhynchus species was more successful the greater the degree of mechanical injury. Based on this study both Eucryptorrhynchus species appear to be secondary pests of A. altissima in China.     

Assessing potential biological control of the invasive plant, tree-of-heaven, Ailanthus altissima

Tree-of-heaven, Ailanthus altissima, is a deciduous tree indigenous to China and introduced into North America and Europe. It is a serious threat to ecosystems in introduced areas, as the plant is very competitive, and also contains allelopathic chemicals that may inhibit growth of surrounding native plants. In addition, the plant contains secondary chemicals that make it unpalatable to some insects. In this paper we assess potential biological control of this plant by reviewing literature associated with natural enemies of the plant from both its native and introduced regions in the world. Our literature surveys revealed that 46 phytophagous arthropods, 16 fungi, and one potyvirus were reported attacking tree-of-heaven, some apparently causing significant damage in China. Two weevils, Eucryptorrhynchus brandti and E. chinensis, are major pests of the plant in China and are reportedly restricted to tree-of-heaven, showing promise as potential biological control agents. Nymphs and adults of a homopteran insect, Lycorma delicatula and larvae of two lepidopteran species, Samia cynthia and Eligma narcissus, may also cause severe damage, but they are not host specific. Two rust fungi, Aecidium ailanthi J. Y. Zhuan sp. nov. and Coleosporium sp. have been reported on tree-of-heaven in China and are also promising potential candidates for biological control of the plant. Nine insect herbivores and 68 fungi are associated with tree-of-heaven in its introduced range in North America, Europe, and Asia. An oligophagous insect native to North America, the ailanthus webworm, Atteva punctella, may be a potential biocontrol agent for the plant. Among the fungal species, Fusarium osysporum f. sp. perniciosum, caused wilt of tree-of-heaven in North America and may have the potential to control the plant, but its non-target effect should be carefully evaluated. Our review indicates that there is potential for using insects or pathogens to control tree-of-heaven.