The chromosome-level genome of double-petal phenotype jasmine provides insights into the biosynthesis of floral scent

Jasmine(Jasminum sambac Aiton)is a well-known cultivated plant species for its fragrant flowers used in the perfume industry and cosmetics.However,the genetic basis of its floral scent is largely unknown.In this study,using PacBio,Illumina,10×Genomics and highthroughput chromosome conformation capture(Hi-C)sequencing technologies,a high-quality chromosome-level reference genome for J.sambac was obtained,exploiting a double-petal phenotype cultivar‘Shuangbanmoli’(JSSB).The results showed that the final assembled genome of JSSB is 580.33 Mb in size(contig N50=1.05 Mb;scaffold N50=45.07 Mb)with a total of 39618 predicted protein-coding genes.Our analyses revealed that the JSSB genome has undergone an ancient whole-genome duplication(WGD)event at 91.68 million years ago(Mya).It was estimated that J.sambac diverged from the lineage leading to Olea europaea and Osmanthus fragrans about 28.8 Mya.On the basis of a combination of genomic,transcriptomic and metabolomic analyses,a range of floral scent volatiles and genes were identified involved in the benzenoid/phenylpropanoid and terpenoid biosynthesis pathways.The results provide new insights into the molecular mechanism of its fragrance biosynthesis in jasmine.

Intraspecific floral colour variation in three Pedicularis species

Flower constancy describes the phenomenon that pollinators tend to successively visit flowers of a single species during foraging,reducing reproductive interference in natural communities.The extent of flower constancy is largely determined by the floral traits of co-flowering species.Both higher inter-specific and lower intraspecific differences of floral traits should contribute to a higher level of flower constancy.However,previous studies mainly focused on interspecific difference,and the intraspecific variation(consistency)of floral traits received much less attention.We hypothesise that selection may favour lower intraspecific floral trait variation in communities composed of multiple co-flowering congeners.We investigated the floral colour variation of three focal Pedicularis species that share pollinators in 19communities composed of either single or multiple Pedicularis species.Colour was quantified using image-based colour analysis as perceived by pollinators.We found that most of the intrapopulation floral colour variation was below the colour discrimination threshold of bumblebees,implying strongly constrained by the visual selection by pollinators.Contrary to the hypothesis,there is no significant difference in intraspecific floral colour variation between different community contexts.It may be due to the relatively large interspecific floral colour differences of most co-flowering species.The influence of community context on intraspecific variation may be reflected in floral traits other than colours.

A chromosome-level genome assembly provides insights into Cornus wilsoniana evolution, oil biosynthesis, and floral bud development

Cornus wilsoniana W.is a woody oil plant with high oil content and strong hypolipidemic effects,making it a valuable species for medicinal,landscaping,and ecological purposes in China.To advance genetic research on this species,we employed PacBio together with Hi-C data to create a draft genome assembly for C.wilsoniana.Based on an 11-chromosome anchored chromosome-level assembly,the estimated genome size was determined to be 843.51 Mb.The N50 contig size and N50 scaffold size were calculated to be 4.49 and 78.00 Mb,respectively.Furthermore,30474 protein-coding genes were annotated.Comparative genomics analysis revealed that C.wilsoniana diverged from its closest species∼12.46 million years ago(Mya).Furthermore,the divergence between Cornaceae and Nyssaceae occurred>62.22 Mya.We also found evidence of whole-genome duplication events and whole-genome triplicationγ,occurring at∼44.90 and 115.86 Mya.We further inferred the origins of chromosomes,which sheds light on the complex evolutionary history of the karyotype of C.wilsoniana.Through transcriptional and metabolic analysis,we identified two FAD2 homologous genes that may play a crucial role in controlling the oleic to linoleic acid ratio.We further investigated the correlation between metabolites and genes and identified 33 MADS-TF homologous genes that may affect f lower morphology in C.wilsoniana.Overall,this study lays the groundwork for future research aimed at identifying the genetic basis of crucial traits in C.wilsoniana.

龙葵UNUSUAL FLORAL ORGANS类SnUFO2基因C端序列的保守性对花发育的影响

【目的】UNUSUAL FLORAL ORGANS(UFO)基因属于F-box基因家族,是重要的花器官特征基因。UFO基因N端能与Skp1类基因结合形成Skp1-Cullin1-F-box(SCF)复合体,参与泛素化过程并降解C端结合的靶蛋白。为了探究C端序列对龙葵Solanum nigrum花发育的影响,本研究克隆了一个C末端缺失的SnUFO2*基因并构建其表达载体转入龙葵植株中,观察转基因龙葵植株花器官变化,从而深入探讨UFO基因完整的C末端序列在龙葵花发育中的重要作用。【方法】利用生物信息学分析软件对SnUFO2*和全长的SnUFO2比较分析,采用实时荧光定量PCR(RT-qPCR)对SnUFO2*基因在野生型龙葵植株根、茎、叶、花苞中进行表达分析;通过超表达载体的构建、转基因植株表型的观察及石蜡切片技术验证SnUFO2基因的功能。【结果】SnUFO2*基因ORF长度为1302 bp,编码433个氨基酸,与龙葵中完整的SnUFO2基因相比,其C末端缺失了23个氨基酸。RT-qPCR结果显示:SnUFO2*基因在野生型植株的花苞中特异性表达。对转基因植株的表型观察发现:35S::SnUFO2*转基因龙葵植株的花瓣向萼片转化。石蜡切片分析发现:转基因龙葵植株雄蕊缺失,雌蕊处有不确定的分生组织产生。【结论】35S::SnUFO2*转基因龙葵植株花瓣、雄蕊和心皮发育异常。C端结构缺失可能降低了SnUFO2蛋白特异性识别靶蛋白的能力,说明该基因完整的C末端对龙葵花器官发育至关重要。

Floral dip法在大豆遗传转化中的应用研究

首次运用floral dip法将植酸酶基因转化大豆品种冀豆12,获得遗传转化率1.18%～2.22%,证明该方法亦可用于大豆的遗传转化;研究了表面活性剂silwet L-77的浓度、转化液中农杆菌的浓度、不同农杆菌菌株对floral dip法大豆遗传转化的影响,结果表明采用EHA105菌株、菌浓度为OD_(600)=2.0、silwet L-77的浓度为0.05%条件下转化率最高。floral dip法在大豆遗传转化上的成功应用为扩展该方法的应用领域、简便有效地提高大豆的遗传转化效率奠定了一定基础。

植物遗传转化的新方法:Floral Dip

目前,遗传转化效率低一直制约着许多作物的分子育种和基因功能研究。Floraldip技术已成为模式植物拟南芥遗传转化的主要手段,该方法在十字花科植物中有广阔的应用前景。本文介绍了此种方法的发展过程和技术原理,并对进一步的研究工作提出了建议。

表面活性剂silwet-77对floral-dip转化甘蓝型油菜效果的影响

利用表面活性剂silwet-77辅助渗透进行floral-dip转化甘蓝型油菜的结果表明,0.1%以上的高浓度表面活性剂silwet-77处理对植株的结实率存在明显的抑制作用,且转化不稳定。0.05%浓度的silwet-77处理获得的转化率较高,未用silwet-77处理的转化频率明显下降。同一浓度的表面活性剂处理下,6d内每隔1d进行连续3次浸渍处理转化频率优于1、2次处理。对13170粒T1代种子进行Km抗性筛选获得了103株抗性植株,对抗性植株进行GUS组织化学检测表明,目的基因已经导入到甘蓝型油菜中,抗性植株进一步的分子检测和田间性状鉴定正在进行中。

通过改良农杆菌介导的floral-dip法和花粉管通道法转化紫薇

以绿色荧光蛋白(GFP)基因为报告基因,分别用改良农杆菌介导的花序浸渍法(floral-dip)和花粉管通道法转化紫薇(Lagerstroemia indica),统计果实数、结实率、成苗率,然后用紫外灯照射28d左右的幼苗筛选转化株。结果表明:花粉管通道法转化紫薇的结实率、成苗率均明显高于floral-dip法;用手携式紫外灯(365nm)照射进行活体鉴定,floral-dip法转化率比花粉管通道转基因法转化率高0.06%,但未达到显著水平;而花粉管通道法的结实率比floral-dip法的高11.87%～26.74%,更利于获得转化植株。说明通过花粉管通道法进行转化更适合于紫薇转基因新品种的培育。

农杆菌介导floral-dip转基因方法研究进展

农杆菌介导的floral-d ip转基因方法是近年发展起来的一种简便、快速、高效、重复性好、稳定性高的非组织培养转基因方法。介绍了该方法的发展、转化原理、转化条件、后代遗传学分析,并讨论了其存在的问题,展望了其在基因工程中的应用前景。

Morphological and Anatomical Analyses of a Floral Organ Mutant in Rice

A spontaneously occurred rice ( Oryza sativa L.) mutant characterized by homeotic conversions in glumes and stamens was found in the progeny of a breeding material. The mutant plant shows degenerated glumes and morphological transformation of stamens into pistils. A mutant floret consists of 1 to 3 completely developed pistils and 4 to 6 incomplete pistils with no ovary. Some pistilloid stamens still have filaments but tipped by bulged tissue and 0 to 3 stigmas. Three ovaries in a single floret were observed in its cross and longitudinal sections. When the mutant plants were pollinated with pollens from wild type plants, one or two naked seeds instead of a caryopsis could be produced in a single floret. The mutant is controlled by a single recessive gene since its F 1 hybrid plants were restored to wild type and 3∶1 ratio of wild type to mutant plants were observed in the progeny of heterozygotes. It seems that the mutant phenotype of the homeotic conversions in glumes and stamens is similar to that of the B loss_of_function mutants in Arabidopsis and Antirrhinum .

CHANGES OF ENDOGENOUS HORMONE CONTENTS DURING FLORAL BUD AND VEGETATIVE BUD DIF FERENTIATION IN THIN CELL LAYER CULTURE OF CICHORIUM INTYBUS L. EXPLANT

The sectioned thin cell layers (TCL) of flower stalk of Cichorium intybus L. were cultured in MS medium supplemented with NAA and BA or IAA and BA where floral and vegetative buds were developed from the explant. Endogenous IAA, DHZ+DHZR, iPA increased significantly during the floral bud formation, while Z+ZR remained changed. The levels of cytokinins, DHZ+DHZR, iPA, and Z+ZR all increased significantly during the vegetative bud formation, however IAA level was reduced during the first 7 days of culture and increased to two thirds of initial values on the day when the bud primordia were formed. The results suggested that the initiation of floral buds was associated with a high IAA/CTK ratio, whereas the induction of vegetative bud differentiation was related to a low IAA/CTK ratio.

Cytological Studies on the Development of Sieve Element and Floral Nectary Tissue in Arabidopsis thaliana

Ultrastructural changes in the sieve element and dense cells of nectariferous tissue during the development of floral nectary in Arabidopsis thaliana L. were investigated with transmission electron microscopy. Samples were prepared with high pressure freezing and freeze substitution techniques. The ultrastructure of dense cell was similar to that of sieve element at its early developmental stage. With the concurrent agglutination of chromatin in the nucleus, the abnormal location of organelles and the high density of cytoplasm, the ultrastructural characteristics in die dense cells of the nectariferous tissue and in the sieve element are matched with those of the programmed cell death in animal and plant reported in recent years. The disorganization of nucleus and most organelles in the differentiation of sieve elements and dense cells is closely associated with the transportation and modification of pre-nectar and the transference of nectar. This suggests that the cytological changes in sieve element and nectariferous tissue are closely associated with the nectary functional activities.

Morphological and Physiological Differences in the Floral Organs of Hosui Pear(Pyrus pyrifolia Nakai) between Normal and Returning Bloom during Late Autumn

[Objective] This study was conducted to investigate the morphological and physiological differences between the flowers opening spring and late autumn of Hosui Asian pear（Pyrus pyrifolia Nakai）. [Method] Pear flowers were collected from normal bloom（NB） and returning bloom periods during late autumn in 2011-2013,respectively. The morphological and physiological indices including pollen number,germination rate, petal length, soluble protein content, soluble sugar content, amino acid content, pollen tube growth, fruiting characteristics of NB and RB flowers were detected and compared. [Result] The filament length and petal area of RB flowers were significantly smaller than those of NB flowers. The contents of soluble proteins, soluble sugars and amino acids of RB pollens were significantly smaller than those of NB flowers. In addition, the abortion rate of RB flowers was higher than that of NB flowers. [Conclusion] RB flowers had complete floral organs and were capable of pollination, but they were different from NB flowers in some morphological and physiological indices.

Floral-dip转化法将PEPC基因ihpRNA干扰表达载体导入甘蓝型油菜

根据磷酸烯醇丙酮酸羧化酶(PEPC)基因控制油菜籽中蛋白质与脂肪酸合成的原理,构建了PEPC基因片段ihpRNA干扰表达载体,该载体包含了一个PEPC基因片段正反向序列的回文结构.表达RNA干扰的载体结构(ihpRNA),在大肠杆菌体内进行克隆的过程中易被大肠杆菌自身携带的某种酶剪切,剪切位点不确定,可能是一种随机性的剪切.通过反复实验,最终获得了一个与我们设计一致的PEPC基因片段正反向序列结构,RNA干扰表达载体构建获得成功.利用花序浸渍法(floral-dip)转基因将构建的PEPC基因ihpRNA干扰表达载体转移到甘蓝型油菜中,并通过抗性筛选、PCR特异扩增、PCR-Southern杂交和克隆测序,对获得的转基因植株进行了鉴定,转化率达到了0.69%,说明floral-dip方法有效地实现了ihpRNA干扰表达载体的遗传转化.

Floral Organogenesis of Titanotrichum oldhamii (Gesneriaceae)

Floral organogenesis of Titanotrichum oldhamii (Hemsl.) Soler., the only species in the genus and endemic to East Asia, was observed under SEM. We found that the development of calyx, corolla and androecium belongs to pentamerous pattern. They come respectively from primordia of calyx, corolla and androecium, and all differentiated from the flower primordium. The zygomorphism of corolla and androecium is derived from quicker growth of the upper lip of corolla and delay in development of the staminode. Initiation of sepal primordia and their development are not consistent in order; the order of initiation is from adaxial central primordium, abaxial two primordia and finally lateral two primordia, while the order of development is first adaxial central sepal, lateral two and finally abaxial two. Sepals are valvate in flower bud. Initiation of corolla lobe primordia and their development are consistent in order, i.e. first abaxial central lobe (central lobe of the lower lip), lateral two (lateral two lobes of the lower lip) and finally adaxial two (two lobes of the upper lip). The aestivation of corolla is imbricate, and the order from outside to inside is the central lobe of the lower lip, lateral two of the lower lip, and finally two of the upper lip or lateral two lobes of the lower lip, two of the upper lip and central one of the lower lip. Stamen primordia are alternate to the corolla lobe primordia, with the anterior two primordia later than the posterior two in initiation; staminode primordium is simultaneous with the posterior two in initiation, but smaller, and opposite to the adaxial carpel (upper lip of stigma). Compared to the patterns of floral organogenesis of Rehmannia (Scrophulariaceae), Whytockia and Rhynchoglossum (Gesneriaceae), the present authors found that the floral organogenesis is diverse and does not form two distinct patterns among these four genera. Based on the results we tend to consider that the conventional demarcation between the Scrophulariaceae and Gesneriaceae using number of ovary locules (two vs one) and placentation (axile vs parietal) is questionable.

Infection of the Anther-smut Microbotryum violaceum in Populations of Silene dioica: Variation in Floral Morphology, Patterns of Spore Deposition and Pathogen-Pollinator Mediated Selection

The anther-smut Microbotryum violaceum ( Brandenburger and Schvinn) G. Deml. and Oberw.) causes a systematic infection of its host Silene dioica ( L.) Clairv., resulting in sterility and production of teliospores (dispersal propagules) in flowers. These spores are transmitted to healthy plants mainly by flower visitors. The behavioral responses of flower visitors to a variation in floral characters are not only likely to affect rates of pollen export/import, but also the rate of spore deposition and probability of disease. In a transplantation experiment, using plants from four different populations, we tested for correlation between variation in female floral morphology and patterns of spore and pollen deposition, and a resulting risk of disease. The source populations in this experiment were located on four islands in Skeppsvik archipelago in northern Sweden, and represented a gradient of disease incidence from completely healthy ( Island 1), low incidence ( Island 2) to high incidences ( Islands 3 and 4) of disease. Fifty plants from each population were transplanted to the center, of the population on Island 4. There were significant differences among the transplants in floral characters, i.e. corolla size, style length and ovule number. Plants from the non-diseased population had larger flowers and longer styles than plants from the highly diseased populations. Numbers of pollen grains and spores deposited on flowers were strongly and positively correlated. We found that plants originating from the non-diseased population captured approximately 4 times more pollen and 9 times more spores, per flower than die individuals from the resident population (Island 4, population 4). The incidences of disease among plants, from the four populations differed significantly, and was 37%, 20%, 18% and 0 for populations 1, 2, 3 and 4 respectively. In a survey of ten populations we found a significant negative correlation between the mean style length ( positively correlated with corolla size and ovule number) among healthy plants and incidence of disease in these populations. The potentiality for pathogen-pollinator mediated selection oil floral characters; and consequences for gone flow between populations of Silene dioica are discussed.

Floral gradient in flowering tobacco in relation to free amino acids

By employing TCLs (thin cell layers) culture, the floral gradient in flowering tobacco of different developmental stages was confirmed. The TCLs from early flowering tobacco regenerated more floral buds than those from the tobacco plants in full blooming or fruiting stages. Analysis of free amino acid levels revealed the acropetal gradient of Pro in flowering tobacco stem. L-Pro. L-Trp. D,L-Met and L-Arg were respectively added into the culture medium for testing their influence on floral bud formation from tobacco pedicel segments. Only L-Trp evidently enhanced the floral bud neoformation.

Floral-dip法大豆GmDREB转录因子转拟南芥研究

DREB(dehydration responsive element binding)转录因子通过调控下游多个抗逆相关基因的表达,能有效提高植物的抗逆性。将构建的植物高效表达载体GmDREB::pCAMBIA1304,借助优化的floral-dip法,转入模式植物拟南芥,并经潮霉素Hygromycine(40～50mg.L-1)抗性筛选得到22棵抗性植株。对抗性植株再进行PCR和GUS检测获得19颗阳性苗,阳性率为86.3%。对T1代种子进行抗性分离比例统计,有4个株系的分离比例接近3:1,符合孟德尔遗传定律,说明外源基因GmDREB在这些株系的染色体中可能是单拷贝插入。继续对上述4个株系的后代进行抗性筛选,现已得到2个纯合的转基因株系。导入的报告基因GUS组织染色检测表明,转入大豆DREB基因在拟南芥的根系和子叶中均有大量表达,并在叶脉中表达。

Floral Organogenesis and Development of Two Taxa in Tribe Hyoscyameae (Solanaceae)-Przewalskia tangutica and Hyoscyamus niger

Floral organogenesis and development of Przewalskia tangutica Maxim. endemic to China and Hyoscyamus niger L., which belong to the tribe Hyoscyameae (Solanaceae), were studied using scanning electron microscope. They have three common characters of floral organ initiation and development: 1) initiation of the floral organs in the two species follows Hofmeister's rule; 2) the mode of corolla tube development belongs to the 'late sympetaly' type; 3) primordia of the floral appendages initiated in a pentamerous pattern and acropetal order. But initiation of the calyx-lobe primordia showed different modes in these two species. The calyx-lobe primordia of H. niger have simultaneously whorled initiation, while those of P. tangutica have helical initiation, but the five calyx-lobe primordia form a ring after all five calyx-lobe primordia occur. The systematic significance of the present results in the genera Hyoscyamus and Przewalskia is discussed in this paper.

Study on Supercooling Point and Freezing Point in Floral Organs of Apricot

Under the environment of an artificial climate chamber, supercooling point （SCP） and freezing point （FP） in flower and young fruit at different development stages and freezing injuries of floral organs were studied. The apricot cultivars tested were Kety, Golden Sun and Honghebao. With the development of flower buds, SCP and FP increased, which indicated that their cold resistance decreased. SCP and FP varied with different floral organs. For different apricot cultivars, it was found that, the lower SCP or FP in floral organs was, the more resistant capacity the cultivar had, and the larger the temperature interval from SCP to FP was. SCP was not a constant value, but a range. Frequency distribution of SCP in petals was more dispersing than that in stamens and pistils. Floral organs could maintain a supercooling state to avoid ice formation, but they were sensitive to freezing. Once floral organs froze, thev turned brown after thawing.