The Floral Nectaries of Hibiscus rosa-sinensis: 1. Development of the Secretory Hairs

Floral nectaries of Hibiscus rosa-sinensis occur on the lowerinner side of the fused sepals and each one consists of numerous(50000–55000) secretory hairs, occupying a cylinder-likezone completely lining the inner side of the sepals. Each hairoriginates from a single protodermal mother cell and, at maturity,it is built up of a basal cell, a stalk, 35–40 intermediatecells and a tip secretory cell. Development of protodermal cellsinto secretory hairs is asynchronous, the first cells to initiatedevelopment being those situated in the lowermost part of thecylindrical zone, and development progressing upwards. Volume increase of protodermal mother cells initiating developmentis accompanied by cell polarization manifested by organelledisplacement towards the apical region. Secretory hairs areformed through a sequence of transverse and, later on, anticlinaldivisions. Divisions of apical cells are preceded by well definedpre-prophase microtubule bands, which foreshadow the plane ofthe forthcoming division and predict with accuracy the sitesof parental walls where the new cell plate fuses at cytokinesis. Stalks consist of either one or two cells. Two-celled stalksoccur in 40 per cent of secretory hairs and derive from a transversedivision of one stalk cell; the wall formed is always depositedparallel to the proximal and distal walls, but never to thelateral ones. The significance of this mode of division is discussedin relation to the fact that lateral walls are entirely impregnatedwith a cutin-like material that blocks apoplastic movement ofsolutes. Hibiscus rosa-sinensis, nectaries, development, preprophase microtuble bands, stalk cells     

Fullerene-Based Symmetry in Hibiscus rosa-sinensis Pollen

The fullerene molecule belongs to the so-called super materials. The compound is interesting due to its spherical configuration where atoms occupy positions forming a mechanically stable structure. We first demonstrate that pollen of Hibiscus rosa-sinensis has a strong symmetry regarding the distribution of its spines over the spherical grain. These spines form spherical hexagons and pentagons. The distance between atoms in fullerene is explained applying principles of flat, spherical, and spatial geometry, based on Euclid’s “Elements” book, as well as logic algorithms. Measurements of the pollen grain take into account that the true spine lengths, and consequently the real distances between them, are measured to the periphery of each grain. Algorithms are developed to recover the spatial effects lost in 2D photos. There is a clear correspondence between the position of atoms in the fullerene molecule and the position of spines in the pollen grain. In the fullerene the separation gives the idea of equal length bonds which implies perfectly distributed electron clouds while in the pollen grain we suggest that the spines being equally spaced carry an electrical charge originating in forces involved in the pollination process.     

Protein Electrophoresis of Single Pollen Grains of Hibiscus rosa-sinensis

Electrophoresis and staining of proteins from the single pollen grains of Hibiscus rosasinensis have been developed by using general ultrathin polyacrylamide gel combined with highly-sensitive silver staining technique. The result revealed that the pollen abortion could occur in different stages of pollen development. The protein patterns varied greatly in different stages of pollen development, even in the different pollen grains in the same anther at the same development stage. Some bands exhibited a disjunction by classical Mendelian ratio 1: 1, suggesting that the gene loci were heterogeneous and the proteins were related to the expression of the genes at the early stage of pollen development.     

Cold-acclimation of Hibiscus rosa-sinensis L. and Hibiscus syriacus L. in natural and controlled environments

Abstract Seasonal cold-acclimation patterns and the effects of photoperiod and temperature on cold-hardiness of Hibiscus rosa-sinensis L. and Hibiscus syriacus L. were determined. Field-grown H. rosasinensis consistently failed to survive freezing at - 2°C. Two genotypes of field- and container-grown H. syriacus initiated cold-acclimation in mid September, in response to decreasing daylength, and continued to an ultimate midwinter hardiness level of - 27°C in early February. Controlled environment experiments using combinations of short days (SD) and cool day/night temperatures were unable to induce even minimal cold acclimation of H. rosasinensis. In controlled environments, H. syriacus attained a moderate amount of cold tolerance at warm temperatures and long days (LD). Low night temperature combined with LD, warm day produced the same degree of cold-acclimation as the SD treatments. While not essential, SD enhanced H. syriacus cold-acclimation in controlled environments. A - 5°C frost treatment of intact plants did not enhance cold-hardiness of H. syriacus.     

Effect of zinc on nectar secretion of Hibiscus rosa-sinensis L

Zinc toxicity in secretory cells caused a range of effects, mainly depending on metal concentration. Low concentrations activated nectary function increasing nectar secretion but secretion was greatly inhibited or stopped entirely by ongoing concentration. Water loss rate of zinc treated flower parts was significantly reduced whereas green sepals were dehydrated more rapidly in comparison to colored petals. The content of zinc, calcium, magnesium and manganese increased mainly in sepals under excess of zinc, but in the secreted nectar this metal was not evident. Morphological changes were observed in mucilage cells concerning the mucilage structure and appearance. The parenchymatic, subglandular cells displayed an early vacuolarization and cytoplasm condensation. Secretory hairs appeared to be thinner, the apical cell folded inwards and plasmolytic shrinkage became severe in all cells. The waxy cuticula showed an increased electron density. A plasmalemma detachment from the external cell walls was observed creating a gap between cell wall and plasmalemma. ER cisterns of all treated nectary hairs dominated the cytoplasm and electron dense deposits were seen within its profiles. A great number of other organelles were also present, showing electron dense deposits in their membranes as well. The vacuome was drastically reduced in all cells, except in the subglandular ones and electron dense membrane remnants were observed.     

Influence of cold temperatures on leaf lipids of Hibiscus rosa-sinensis

Triaclyglycerols (TAG) accounted for 15% of the leaf acyl lipids in a Hibiscus rosa-sinensis plant that survived the January 1986 freeze in Florida, U.S.A. This high TAG level suggested that the plant had cold hardened. The TAG concentration in leaves on new shoots from this plant was greater than that in new leaves on new shoots from five plants frozen to the roots during the freeze. However, five months later, the amounts of TAG in the six Hibiscus plants were nearly the same. The minor differences in TAG levels, however, related to the survival rate of these six plants during subsequent freezes. In addition to linoleic acid, two cyclopropene fatty acids, malvalic and sterculic, were major constituents of the leaf TAG. Hibiscus plants placed in environmental chambers under control and cold-hardening regimes optimized for Citrus showed TAG concentrations of 7% in control and 20% in hardened plants. A survey of neutral lipids in Hibiscus and other plants showed that plastoquinone A (B) and α-tocopherol decreased and plastoquinone C increased under cold-hardening conditions. Polyprenols, a major component of Hibiscus leaves under normal conditions, declined greatly under cold-hardening regimes.     

The floral nectaries of Hibiscus rosa-sinensis in. A morphometric and ultrastructural approach

The secretory hairs of Hibiscus rosa-sinensis nectaries have been studied ultrastructurally, particularly at stages before, during and after secretion. Morphometric cytology revealed considerable changes in the volume of endoplasmic reticulum (ER) and the vacuoles. At least three different forms of ER have been noticed, cisternal, tubular and vesicular. The intermediate cells of the hairs are ultrastructurally and morphometrically similar to the tip cell, suggesting their probable involvement both in a symplastic prenectar transport via the plasmodesmata and in nectar release into an extracellular space provided by the lateral cell walls. Nectar would then be apoplastically moving towards the tip cell, where it is forcibly expelled to the outside via transient pores of the cuticle.
Ultrastructural evidence indicates that ER is the cell compartment principally involved both in prenectar transport and nectar elimination. In the hair cells it provides a "secretory reticulum" mediating between prenectar accumulation and nectar release. Vacuoles are voluminous in the basal cells, and in all cell types of old nectaries. The results are discussed in relation with other plant glands, especially with the closely related Abutilon nectaries.     

Influence of phloem transport on flower abscission in Hibiscus rosa-sinensis

Summary Flowering cultivars of Hibiscus rosa-sinensis L. were either cross-pollinated or self-pollinated. Fruit set was observed on 52% of the cross-fertilized flowers, while only 4.6% of the self-fertilized flowers were not abscised. Once during fruit and seed growth, the subtending leaf was exposed to ¹⁴CO₂, and translocation of labelled photoassimilate was recorded by macro- and microautoradiography. Phloem transport into the raphe occurred in both fruits with fertilized and fruits with non-fertilized ovules. Since empty ovules showed some sink strength, it is assumed that growth of vegetative seed-tissue signalizes the retardation of completion of the abscission process. During fruit growth a considerable amount of starch is deposited in the distal layer of the abscission zone. Part of this starch is consumed during growth of cross-fertilized fruits.     

Genomic insights into a Pseudomonas amygdali isolate from Hibiscus rosa-sinensis

The taxonomy of Pseudomonas has been extensively studied, yet the determination of species is currently difficult because of recent taxonomic changes and the lack of complete genomic sequence data. We isolated a bacterium causing a leaf spot disease on hibiscus (Hibiscus rosa-sinensis). Whole genome sequencing revealed similarity to Pseudomonas amygdali pv. tabaci and pv. lachrymans. The genome of this isolate (referred to as P. amygdali 35–1) shared 4987 genes with P. amygdali pv. hibisci, but possessed 204 unique genes and contained gene clusters encoding putative secondary metabolites and copper resistance determinants. We predicted this isolate's type III secretion effector (T3SE) repertoire and identified 64 putative T3SEs, some of which are present in other P. amygdali pv. hibisci strains. Assays showed that the isolate was resistant to copper at a concentration of 1.6 mM. This study provides an improved understanding of the genomic relatedness and diversity of the P. amygdali species.     

Hibiscus latent ringspot virus, a newly recognised virus from Hibiscus rosa-sinensis (Malvaceae) in western Nigeria

Hibiscus latent ringspot virus (HLRV) was prevalent in Hibiscus rosa-sinensis in Ibadan, Nigeria. It was readily transmitted mechanically to 22 of 73 species from seven of 20 families, but was best propagated in Nicotiana clevelandii or Hibiscus cannabinus and assayed in Chenopodium murale. HLRV was readily purified from systemically infected hosts by differential centrifugation of leaf extracts clarified with 8.0% n-butanol, followed by molecular permeation chromatography on controlled-pore glass beads (700 Å, 120–200 mesh). The virus has isometric particles c. 28 nm in diameter which sedimented as three components (T, M and B), with sedimentation coefficients (s°_{20, w}) of 51; 114 and 132 S and buoyant densities in caesium chloride of 1.32, 1.49 and 1.52 g/cm³, respectively. All three components contained a single polypeptide of rnol. wt 53.6 × 10³. T component particles contained only protein but M and B components also contained single-stranded RNA of rnol. wt 2.2 × 10⁶ and 2.5 × 10⁶, respectively. The properties of HLRV suggest affinities with nepoviruses but no serological relationship was detected between HLRV and 15 recognised or possible members of the nepovirus group.     

Preparative HPLC fraction of Hibiscus rosa-sinensis essential oil against biofilm forming Klebsiella pneumoniae

Recent years Klebsiella pneumoniae (K. pneumoniae) biofilm formation (BF) is emerging thread worldwide. For tackling this problem, we have chosen Hibiscus rosa-. pneumoniae. The HPLC purified essential oils (EOs sinensis (H. rosa-sinensis) (HRS) to inhibit the BF K) of H. rosa-sinensis was performed against BF K. pneumoniae and showed concentration dependent biofilm inhibition. At the MBIC of EOs (90 µg/ml), the biofilm inhibition was showed at 92% against selected BF K. Pneumoniae. The biofilm metabolic assay, exopolysaccharide quantification and hydrophobicity index variation results exhibited with 88%, 92% and 89% reduction at 90 μg/mL was observed respectively. In addition, the morphological modification of MBIC treated K. pneumoniae was clearly viewed by scanning electron microscope (SEM). Overall, all the invitro experiments result were confirmed that the MBIC of H. rosa-sinensis EOs was very effective against BF K. pneumonia.     

响应面法优化扶桑叶黄酮超声提取工艺

以扶桑叶为研究材料,以Box-Behnken中心组合实验设计,利用响应面法对扶桑叶黄酮提取工艺进行优化。结果表明,超声波辅助乙醇提取扶桑叶黄酮优化工艺条件为乙醇浓度70%,超声提取时间70 min,液料比40∶1。在最佳工艺条件下扶桑叶黄酮提取的得率最高,为34.56 mg/g。     

不同密度棉花粉蚧种群对扶桑生长的影响

棉花粉蚧Phenacoccus solenopsis Tinsley是我国一种重要外来入侵害虫.关于该害虫入侵发生对作物的危害程度一直是关注的重要方面.本文通过定量接种虫量的方法,研究了棉花粉蚧初孵若虫不同初始密度(50头/株、100头/株、200头/株、400头/株、800头/株)下扶桑苗生长规律.结果植株生长表明,...     

Isolation and characterization of microsatellite markers from Hibiscus rosa-sinensis (Malvaceae) and cross-species amplifications

We report on the development of 10 microsatellite markers in Hibiscus rosa-sinensis (Hrs). Three markers were obtained from sequences available in GenBank and seven were isolated using a two-step ‘primer extension’ procedure, based on the microsatellite-AFLP (M-AFLP) technique. Polymorphism was explored in 21 Hrs genotypes representing the genetic variation within commercial varieties. Inter-specific amplification was assessed on 12 Hibiscus wild species. A total of 45 and 56 alleles (ranging from 1 to 10 for each locus) was amplified respectively from the 21 Hrs varieties and among the full Hibiscus spp. genotype set. Primers and conditions for polymerase chain reaction (PCR) amplification of the detected loci are reported.     

Chloroplast genome of Hibiscus rosa-sinensis (Malvaceae): Comparative analyses and identification of mutational hotspots

Previous studies to resolve phylogenetic and taxonomic discrepancies of Hibiscus remained inconclusive. Here, we report chloroplast genome sequence of Hibiscus rosa-sinensis. Hibiscus rosa-sinensis chloroplast genome was 160,951 bp, comprising of large single copy (89,509 bp) and small single copy (20,246 bp) regions, separated by IRa and IRb (25,598 bp each). The genome contained 130 genes including 85 protein-coding genes, 37 transfer RNAs and 8 ribosomal RNAs. Comparative analyses of chloroplast genomes revealed similar structure among 12 species within family Malvaceae. Evolutionary rates of 77 protein-coding genes showed 95% similarities. Analyses of codon usage, amino acid frequency, putative RNA editing sites, and repeats showed a great extent of similarities between Hibiscus rosa-sinensis and Hibiscus syriacus. We identified 30 mutational hotpots including psbZ-trnG, trnK-rps16, trnD-trnY, trnW-trnP, rpl33-rps18, petG-trnW, trnS-trnG, trnH-psbA, atpB-rbcL, and rpl32-trnL that might be used as polymorphic and robust markers to resolve phylogenetic discrepancies in genus Hibiscus.     

Production of taxol from Phyllosticta dioscoreae, a leaf spot fungus isolated from Hibiscus rosa-sinensis

Taxol is a highly functionalized anticancer drug widely used in hospitals and clinics. The leaf spot fungus, Phyllosticta dioscoreae was isolated from diseased leaves of Hibiscus rosa-sinensis and screened for extracellular production of taxol in M1D (Modified liquid medium) and PDB (Potato dextrose broth) medium for the first time. The fungus was identified by its morphological and conidial features in the culture growth. The presence of taxol in the fungal culture filtrate was confirmed by different spectroscopic and chromatographic analyses. The amount of taxol produced was quantified by HPLC. The maximum amount of taxol produced was found to be 298 μg/L in M1D medium. Production rate was 5.96 × 10³ times faster than that found in culture broth of earlier reported fungus, Taxomyces andreanae. The extracted fungal taxol also showed strong cytotoxic activity in vitro in the cultures of human cancer cells tested by apoptotic assay. The results indicate that P. dioscoreae is an excellent source of taxol production, which suggests that the fungus has potential to undergo genetic engineering in order to improve its production level.     

海南岛番木瓜和扶桑上粉虱传双生病毒的检测及序列分析

粉虱传双生病毒(Whitefly-transmitted gemini-virus,WTGV)是一类广泛发生在热带、亚热带地区植物上的具有孪生颗粒形态的单链DNA病毒,在分类上属双生病毒科(Geminiviridae)的菜豆金色花叶病毒属(Begomovirus),该属的大多数病毒都由2个组分(DNA-A和DNA-B)组成,为两条闭合环状ssDNA分子,长度相似,每条为2.5-2.8kb,少数病毒为单组分,仅有DNA-A组分[1]。我国自1983年报道发现双生病毒以来,在云南、广西、广东和海南等省区的已相继发现多种双生病毒[2~6],表明这类病毒在我国的危害有蔓延和加重的趋势。本文对从海南番木瓜(Carica pap…     

侵染朱槿的木尔坦棉花曲叶病毒及其卫星DNA全基因组结构特征

从广州朱槿上分离到病毒分离物G6,全序列测定结果表明,G6 DNA-A全长为2 737个核苷酸.序列比较显示,G6 DNA-A与木尔坦棉花曲叶病毒(CLCuMV)各分离物的同源率均大于89%,其中与CLCuMV-[62]的同源率最高(96.1%),与拉贾斯坦棉花曲叶病毒(CLCuRV)的同源率87.1%～89.8%,而与其他菜豆金色花叶病毒属病毒同源率均在87%以下.DNA-A系统进化关系分析显示,G6与CLCuMV各分离物的亲缘关系最近,聚在一起形成一个分支,而与其他几种双生病毒的亲缘关系相对较远.利用DNAβ特异引物β01和β02,从G6中扩增到卫星DNA分子(DNAβ).序列分析结果表明,G6 DNAβ全长1 346个核苷酸,推导其互补链上编码一个ORF(C1).序列比较结果表明,G6 DNAβ与CLCuMV DNAβ的同源率最高(92.1%),与CLCuRV DNAβ的同源率为88.7%,而与其他已报道的DNAβ的同源率均在80%以下.DNAβ系统进化关系分析显示,G6 DNAβ与CLCuMV DNAβ形成一个独立的分支,再与CLCuRV及MYVV-[Y47]的DNAβ形成一个较大分支.从上述研究结果可以得出,侵染广东朱槿的病毒分离物G6应该是CLCuMV一个分离物.     

海南岛番木瓜和扶桑上粉虱传双生病毒的检测及序列分析

粉虱传双生病毒(Whitefly-transmitted geminivirus,WTGV)是一类广泛发生在热带、亚热带地区植物上的具有孪生颗粒形态的单链DNA病毒,在分类上属双生病毒科(Geminiviridae)的菜豆金色花叶病毒属(Begomovirus),该属的大多数病毒都由2个组分(DNA-A和DNA-B)组成,为两条闭合环状ssDNA分子,长度相似,每条为2.5-2.8kb,少数病毒为单组分,仅有DNA-A组分[1].我国自1983年报道发现双生病毒以来,在云南、广西、广东和海南等省区的已相继发现多种双生病毒[2～6],表明这类病毒在我国的危害有蔓延和加重的趋势.本文对从海南番木瓜(Carica papaya)和扶桑(Hibiscus rosa-sinensis)上采集到的表现典型双生病毒症状的样品进行了分子检测,并对序列进行了分析.