二型花柱植物海仙花报春花部性状随地理梯度的变异

植物的花部性状在异质环境中表现出不均一的适应性进化, 其自然变异可能在时空格局上呈现一定的规律性。选择同一物种的不同地理居群进行花部表型变异分析, 能揭示花部性状随地理梯度的变异模式。海仙花报春(Primula poissonii)属于典型的二型花柱植物, 依赖昆虫传粉实现严格的型间异交。该物种广布于横断山地区亚高山-高山草甸, 其分布海拔跨度大且花部性状在种内具有较高变异, 但这些变异在不同地理梯度(海拔梯度和经纬度梯度)的特定选择因子作用下的变化规律尚不清楚。本研究选择海仙花报春16个居群, 对8个花部关键性状和二型花柱繁殖器官的互补度与海拔和经纬度的关系进行研究, 探究花部性状随地理梯度变异的模式及其潜在的选择因素。研究表明, 海仙花报春两种花型的花冠管开口大小、花药高度以及短柱花柱头高度与海拔均呈正相关, 但两种花型的花冠大小, 长柱花的花瓣长度、柱头到花冠管开口的距离, 以及短柱花的花冠管长度与海拔高度间均呈负相关, 其余性状与海拔无显著相关性。除短柱花中柱头高度以外的性状均随着纬度升高而逐渐减小。长柱花中除花药和柱头间的距离以及柱头到开口的距离外, 其余性状均随着经度的增加而减小; 短柱花的花瓣长度、花药高度以及花药和柱头间的距离随着经度的增加而变大, 其余性状均随着经度的增加而减小。繁殖器官间的互补度并不随地理环境的变化而变化。花部性状的地理变异可能受访花昆虫组成的地理变化驱动。繁殖器官间互补程度的高度保守表明非选型交配在居群二态性的维持和稳定过程中起关键作用。本研究为进一步深入开展报春花属(Primula)花部性状及其选择压力的地理变异研究奠定了基础。     

“金虎尾路线”植物的花进化与传粉转变

以金虎尾科植物地理分布格局及迁移历史总结出来的“金虎尾路线”, 是解释热带植物洲际间断分布与长距离扩散格局的重要模式。金虎尾路线阐明了金虎尾科植物历史时期7次独立的从起源中心(南美洲)向旧世界(非洲和亚洲)的洲际长距离扩散事件。本文总结了金虎尾路线植物起源地与扩散地主要类群的花部特征与传粉系统, 以探讨这些类群及类似植物长距离扩散后的花进化与传粉转变等适应规律。金虎尾科的南美洲类群都有分泌油脂的萼片腺体, 花的形态结构非常保守, 是与美洲当地特有的条蜂科集油蜂长期协同进化的结果。金虎尾科的非洲类群花保守性消失, 花白色、辐射对称且无萼片腺体, 繁育系统为雄花-两性花异株(功能性的雌雄异株), 传粉者是采集花粉的蜜蜂科昆虫。亚洲的一些属发生了类似非洲类群的泛化适应转变, 但风筝果属(Hiptage)出现了镜像花、异型雄蕊和极度反折的花瓣, 且传粉者是亚洲特有的大蜜蜂(Apis dorsata), 显示出了非常特化的适应性转变。风筝果属所在支系的现存类群涵盖了南美洲、中美洲、非洲和亚洲等地的地方特有属, 体现了金虎尾路线整个迁移历史过程, 是认识金虎尾路线及其进化适应规律的关键类群, 值得在今后的研究中加以重视。     

Diversification of floral orientation in Lonicera is associated with pollinator shift and flowering phenology

Floral orientation has been suggested to be a functional floral trait that can enhance reproductive fitness through adaptation to both biotic factors (e.g., pollination) and abiotic factors (e.g., temperature). However, whether those factors drive the diversification of floral orientation needs to be explored through multiple related species. Phylogenetic relationships in Lonicera were identified by incorporating the species’ floral orientation (upward vs. downward) and pollinator types. Furthermore, transitions in floral orientation were evaluated together with pollinator shift, and seven Lonicera species were used to detect the influence of floral orientation on pollination and reproductive success. The relationship between temperature and the angle of floral orientation was investigated. Floral orientation in Lonicera showed that most of the closely related species within the same node displayed a similar pattern of floral orientation, and pollinator shift can lead to transitions between upward and downward orientation. Additionally, the angle of floral orientation increased with flowering phenology from spring to summer, and changing floral orientation significantly decreased pollination and seed production. Moreover, the average daily temperature during flowering phenology was significantly correlated with the angle of floral orientation. Our results indicate that pollinator shift could be an important event, leading to the diversification of floral orientation. Results of field investigations inferred that floral orientation should be a functional floral trait adapted to flowering phenology. Downward-facing flowers might help decrease heat loss to adapt to cold conditions. This study disentangled the influences of historical events and local adaptation on the evolution of floral orientation.     

Floral anthocyanins in the genus Puya

A survey of floral anthocyanins among ten species of Puya shows the predominant pigment to be delphinidin 3,7,3′-triglucoside. This is the first report of the natural occurrence of this pigment in a non-acylated form. The occurrence of this unusual glucosylation pattern in Puya supports a close alliance between the Bromeliaceae and Commelinaceae.     

Floral morphogenesis of the Maddenia and Pygeum groups of Prunus (Rosaceae), with an emphasis on the perianth

Although the vast majority of Prunus L. (Rosaceae) species have clearly differentiated sepals and petals, two former genera Maddenia and Pygeum have been described as having an undifferentiated perianth. However, floral morphological and morphogenetic data are scarce, and a renewed investigation is essential to understand the evolution of the perianth differentiation. Here, floral morphogenesis in Prunus hypoleuca (Koehne) J.Wen (=Maddenia hypoleuca Koehne) and Prunus topengii (Merr.) J. Wen & L. Zhao (=Pygeum topengii Merr.) were examined with scanning electron microscopy. The floral development demonstrates that the ten perianth parts can be distinguished as five sepals in an external whorl and five petals in an internal whorl. The sepal primordia are broad, crescent-shaped, and truncate. The petal primordia are rounded and initially resemble the androecium. However, at maturity petals and sepals look much the same in the two species, differing from other Prunus species. The ovule is anatropous and unitegmic, but there is a basal appendage near the ovule of P. hypoleuca which is absent in P. topengii. The direction of development of floral nectaries in the hypanthium is basipetal in P. hypoleuca but acropetal in P. topengii. Perianth segments are differentiated in the two groups and the similarity of the perianth parts is secondarily acquired. Our results support the separation of the Maddenia and Pygeum groups as well as their inclusion in a broader monophyletic Prunus based on molecular phylogenetic studies. We herein provide a new nomenclatural change: Prunus topengii (Merr.) J. Wen & L. Zhao, comb. nov.     

Loss of innovative traits underlies multiple origins of Aquilegia ecalcarata

Traits are basic attributes of organisms that form the basis for speciation and diversity. The floral nectar spur is a classic example of a key innovative trait. Differences in nectar spur morphology can lead to pollinator specialization and thereby promote reproductive isolation between species. Despite its importance, the nectar spur has been lost in some members of the columbine genus (Aquilegia), resulting in a new spurless trait, and the evolutionary influence of this trait has become a topic of scientific interest. Aquilegia ecalcarata is an important representative columbine species that lacks spurs. Here, we resequenced the genomes of 324 individuals from A. ecalcarata and four related species. We found that A. ecalcarata was divided into three groups based on the phylogenetic relationships and population genetic structures. Topology weighting analysis revealed that A. ecalcarata has multiple origins, and Patterson′s D statistic showed that the spurless trait may have one origin. Floral morphological analysis revealed significant differences between A. ecalcarata and its spurred sister groups, and the floral phenotypes of the three A. ecalcarata groups have identical or similar floral phenotypes. Our results confirmed that the spurless trait not only produced the phenotype of A. ecalcarata but also contributed to the emergence of the A. rockii phenotype. Moreover, the spurless trait promoted the divergence between A. ecalcarata and its close, spurred relatives. Our research shows that the loss of key innovative traits can play a very important role in speciation and species diversity.     

不同大花类群淫羊藿属植物的花部特征及生殖特征研究

淫羊藿是我国重要的草本植物,在中药、功能性食品和园林观赏等领域都具有重要用途,受地域差异性影响,淫羊藿属植物的植株形态、花部特征、开花物候和生殖特征各不相同。本研究对四川不同产地野生种群大花类淫羊藿（巫山淫羊藿、粗毛淫羊藿和宝兴淫羊藿）的开花动态、花部特征、访花昆虫与繁殖系统进行了对比研究。结果表明：（1）3种淫羊藿属植物的开花期较为集中,巫山淫羊藿和粗毛淫羊藿的花期为3月下旬～4月下旬,单花花期均为3～4 d;宝兴淫羊藿的花期为4月中旬～5月中旬,单花花期5～6 d;（2）膜翅目和双翅目昆虫为3种淫羊藿属植物的有效访花者,有效访花者访花特性与花部特征之间具有明显的相关性;（3）3种淫羊藿属植物的花序、花和果实的数量受所处环境影响较大,自然结实率：巫山淫羊藿>宝兴淫羊藿>粗毛淫羊藿;温度和光照是最主要的影响因子。     

Pollination and seed dispersal of Aquilaria sinensis (Lour.) Gilg (Thymelaeaceae): An economic plant species with extremely small populations in China

Pollination and seed dispersal in angiosperms have long been investigated in order to understand the coevolution of plants and animals. However, the signals from flowers and/or seeds to attract pollinators and/or seed dispersers have received comparatively little attention. In this study, the pollination biology and seed dispersal of the vulnerable agarwood plant Aquilaria sinensis (Lour.) Gilg, a traditional medicinal plant in China, was studied in its natural distribution range. The reproductive tactics of A. sinensis were studied in detail by employing various tests dealing with fruit set and also seed dispersal. Dynamic headspace extraction followed by GC-MS analysis was also performed in order to reveal the composition of floral scent. The results showed that noctuids and pyralids are the most effective pollinators of pollinator-dependent A. sinensis. The main compounds of the floral scent were (E, E)-α-Farnesene (61.9±3.2%), trans-Ocimene (16.6±1.2%), and Benzyl salicylate (4.6±1.1%). The results obtained from seed dispersal experiments indicate that hornets are effective seed dispersers and they may play an important role in long-distance seed dispersal of A. sinensis. Based on our findings, we recommend several protection methods for this threatened agarwood plant in China.     

浅裂剪秋萝和丝瓣剪秋萝传粉特性的初步研究

为了探究浅裂剪秋萝(Lychnis cognata)和丝瓣剪秋萝(L. wilfordii)的传粉生物学特征, 从花部特征、花粉呈现规律及传粉者访花行为等方面对其开展研究。结果表明, 2种剪秋萝的花期持续时间相近, 但浅裂剪秋萝始花日期较早; 二者花部特征虽有显著差异, 但主要传粉者均为碧翠凤蝶(Papilio bianor)。在开花过程中, 2种剪秋萝的雄蕊均分2批呈现花粉, 第1批雄蕊的花粉生活力在开花后第1天达到最大值, 而第2批雄蕊在第2天达到最大值。浅裂剪秋萝的柱头可授性在开花后第5天最强, 而丝瓣剪秋萝在开花后第4天最强, 花粉生活力和柱头活性的时间差异表明两物种均为雌雄异熟。两物种共同的传粉者碧翠凤蝶对浅裂剪秋萝的访花高峰出现在上午8:00-11:00, 而对丝瓣剪秋萝的访花高峰出现在上午11:00-12:00, 导致访花高峰出现差异的主要影响因素可能是生境和花药开裂时间。     

野生大豆花发育相关基因GsLFY的功能研究

LEAFY/FLORICAULA (LFY/FLO)是植物特有的转录因子家族,在控制花器官的诱导与发育中起着重要的作用,但是与野生大豆花发育相关的LFY/FLO同源基因的研究尚未见报道。本研究从野生大豆中克隆获得1个LFY同源基因,命名为GsLFY,该基因CDS全长1224 bp,包含完整的开放阅读框,编码407个氨基酸。利用实时荧光定量PCR技术对GsLFY在不同组织中的表达情况进行了分析,结果显示GsLFY在根、花以及种子中表达,在茎、叶、茎尖中不表达; 在花发育的四轮不同器官中(萼片、花瓣、心皮和雄蕊)进行实时荧光定量PCR,结果显示GsLFY在花萼和雄蕊中表达,在花瓣和心皮中不表达。酵母单杂交实验结果显示,GsLFY具有转录激活活性。拟南芥原生质体瞬时表达结果表明,GsLFY定位于细胞核中。转GsLFY基因烟草植株开花期比对照提前约29 天,这为通过分子育种的方法获得花期改变的大豆新品种提供了基因资源和理论基础。     

Morphological study of floral nectaries in Euonymus and the probable origin of the echinate fruit surface

A conspicuous nectary disk is common but has a distinguishing morphology in the cosmopolitan genus Euonymus. Our study focuses on the morphology of floral nectaries in 21 representatives of Euonymus and Glyptopetalum. Two main types of nectaries were documented:a mix of inter-and extrastaminal nectaries existed between the corolla and the stigma, while the intrastaminal nectaries were distributed between the stigma and the stamen bases. The main route of nectar release in Euonymus is via modified stomata, and different nectarostomata locations were observed:in depressions, slightly raised above the epidermal surface or at the same level as the epidermis. Floral nectaries in E. sect. Echinococcus species developed into the protrusions on the fruit surface at the later stage. The development of nectaries not only explained the mystery of the origin of the echinate fruit surface, but also showed that differences in fruit surface might be inappropriate for use in infrageneric classification. These discoveries inform morphological observations of floral nectaries in Euonymus.     

Characterization of the pectin methylesterase-like gene AtPME3: a new member of a gene family comprising at least 12 genes in Arabidopsis thaliana

Pectin demethylesterification appears to be catalysed by a number of pectin methylesterase (PME) isoenzymes in higher plant species. In order to better define the biological role of these isoenzymes in plant cell growth and differentiation, we undertook molecular studies on the PME-encoding genes in Arabidopsis thaliana. In this paper, we report the characterization of AtPME3, a new PME-related gene of 4 kb in length that we have mapped on Chromosome III. AtPME3 encodes a putative mature PME-related isoenzyme of 34 kDa with a basic isoelectric point. Since the extent of the gene family encoding PME in higher plant species is still unknown, we resorted to the use of degenerate primers designed from several well-known consensus regions to identify new PME-related genes in the genome of Arabidopsis. Our results, in combination with several known expressed sequences tags (ESTs), indicate that the Arabidopsis genome contains at least 12 PME-related genes. Consequently, a method of systematic gene expression analysis has been applied in order to discern the expression pattern of these 12 genes throughout the plant at the floral stage. Whereas most of these genes appeared to be more or less ubiquitously expressed throughout the plant, several genes are distinguishable by their strikingly specific expression in certain organs. The present data bring a new insight into the role of specific PME-related genes in flower and root development.     

中国百合科(广义)植物趋同特征的讨论——浆果和蒴果

分类学家在讨论分类群之间的关系时,首先要分析分类性状的特点。其中有一种性状,所谓趋同性状者(Convergent character),常扰乱我们对分类群之间真正谱系关系的阐明,这是众所周知的事。     

Out of the Pan-Himalaya: Evolutionary history of the Paeoniaceae revealed by phylogenomics

Peonies (the Paeoniaceae, Paeonia L.) are famous garden flowers, medicinal plants, and edible oil crops, but their evolutionary history largely remains unknown. To probe into their phylogenetic relationships, evolutionary history, formation of present distribution pattern, and origins of tetraploids, we sequenced 25 fragments belonging to 20 single copy nuclear genes and 14 chloroplast regions of all species in the genus to reconstruct phylogenetic relationships, date the divergence times of lineages, infer the ancestral biogeographical regions, and document the parents of tetraploids. Our results show that Paeoniaceae separated from the other members in Saxifragales in the Campanian of the late Cretaceous and diverged into two clades, woody and herbaceous clades, in the late Oligocene or early Miocene. They survived and early diverged in the Pan-Himalaya where they migrated eastwards to East Asia and further to NW America, and northwards to Middle Asia, and further to Europe. The woody lineage differentiated into two sublineages with accelerated root or floral disk evolution, while the herbaceous lineage diverged into five sublineages. Multiple glacial and interglacial cycles in Europe in the late Pliocene and early Pleistocene created opportunities for the peony species to meet and hybridize in the Mediterranean refugia, giving rise to eight allotetraploid species and four infraspecific tetraploids. Paeonia daurica Andrews, P. obovata Maxim., and P. tenuifolia L. served as the most important parents. The phylogeny of Paeonia L. implies that a new taxonomic system with two subgenera and seven sections should be proposed.     

Function of the apetala-1 gene during Arabidopsis floral development.

We have characterized the floral phenotypes produced by the recessive homeotic apetala 1-1 (ap1-1) mutation in Arabidopsis. Plants homozygous for this mutation display a homeotic conversion of sepsis into brachts and the concomitant formation of floral buds in the axil of each transformed sepal. In addition, these flowers lack petals. We show that the loss of petal phenotype is due to the failure of petal primordia to be initiated. We have also constructed double mutant combinations with ap1 and other mutations affecting floral development. Based on these results, we suggest that the AP1 and the apetala 2 (AP2) genes may encode similar functions that are required to define the pattern of where floral organs arise, as well as for determinate development of the floral meristem. We propose that the AP1 and AP2 gene products act in concert with the product of the agamous (AG) locus to establish a determinate floral meristem, whereas other homeotic gene products are required for cells to differentiate correctly according to their position. These results extend the proposed role of the homeotic genes in floral development and suggest new models for the establishment of floral pattern.