Antioxidant Properties of Heat-treated Hibiscus syriacus

The antioxidant properties of heat-treated Hibiscus syriacus was investigated using DPPH test. The stems and the roots of Hibiscus syriacus were examined, respectively. As a result, the extracts of heat-treated Hibiscus syriacus at 100°C for 24 h were more effective than those of non-treated Hibiscus syriacus in reducing the stable free radical 1,1-Diphenyl-2-picrylhydrazyl (DPPH).     

木槿属植物海滨木槿的研究进展

近几十年来,从木槿属植物中分离得到多种化合物,如木脂素、黄酮、萜类、mansonones类等化合物类型。文章重点介绍了木槿属及该属植物海滨木槿的研究进展,有助于对该属植物海滨木槿的进一步开发与研究。     

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.     

Cytogenetic characteristics and the breeding system in six Hibiscus species

Cytogenetic characteristics confirm that Hibiscus acetosella and Hibiscus cannabinus are outbreeders, while Hibiscus asper, Hibiscus physaloides, Hibiscus sabdariffa and Hibiscus surattensis have evolved into inbreeders. The inbreeding species appear to have co-evolved a floral structure in which some anthers abut on the stigma prior to anthesis. Received: 19 February 1999 / Accepted: 17 June 1999     

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.     

棉蚜在木槿上的扩散迁飞动态

对木槿和棉株上棉蚜自然种群消长动态、扩散及迁飞动态研究表明,木槿上棉蚜两种水平空间格局４月２０ 日～５ 月６ 日一直都是聚集格局,东向方位数量偏多,以株为单位第４ 、第１０ 株偏多,５ 月６ 日后扩散引起了格局变化;天敌中大草蛉与棉蚜数量之间相关,棉蚜与各种天敌总量极相关,天敌对棉蚜种群数量影响程度的顺序关联度显示为龟纹瓢虫＞ 食蚜蝇＞ 大草蛉;４ 月１８ 日～５ 月１６ 日木槿上棉蚜种群增长模型为线性模型;气象因子中前一天的大气相对湿度与木槿上棉蚜成若蚜总有翅率相关显著;大田棉蚜成蚜有翅率与提前２天木槿上棉蚜成蚜有翅率之间极相关．     

Kenaf (Hibiscus cannabinus), roselle (Hibiscus sabdariffa)

Uses of 16 species of Hibiscus, section Furcaria DC, are discussed, with particular reference to kenaf (H. cannabinus L.) and roselle (H. sabdariffa L.), the two most important species grown commercially as fiber plants. Other uses of this versatile group include use as ornamentals and employment of various plant parts as food, medicine, wood for musical instruments, and in superstitious rites. Comparative morphology of certain vegetative and floral parts of 11 species and seeds of 12 species is discussed. Reaction of plants of 11 species to root-knot nematodes is reported. Ratings varied from highly susceptible to highly resistant; kenaf was more susceptible to nematodes than the other 10 species. Suggested origins, distribution, and genetic relationships of kenaf, roselle, and related species are treated.     

Identification, purification and some properties of a mosaic virus of okra (Hibiscus esculentus)

In the Ivory Coast, an apparently undescribed virus was isolated from okra (Hibiscus esculentus) in which it caused mosaic and leaf vein banding. The virus was sap transmissible to a wide range of plants and had a thermal inactivation point of 80 °C. It was named okra mosaic virus (OMV). A purification procedure was developed. Electron microscopy and analytical and density gradient centrifugation showed that OMV was an isometric virus accompanied by empty shells (top component). Serological tests showed OMV to be a member of the tymovirus group.     

木槿属植物染色体倍性与花粉粒、叶片气孔器性状的关系

测定了木槿属植物裂瓣槿(Hibiscus schizopetalus (Masters)．Hook．f.)、木芙蓉(H.mutabilis L.)和扶桑(H.rosa-sinensis L．)及扶桑的3个栽培变种重虹中玫槿(H．rosa-sinensis L．cv．Double Rainbow)、橙黄中玫槿(H.rosa-sinensis L.cv．Flavo-plenus)、洋红中玫槿(H.rosa-sinensis L.cv．Carminatus)的气孔器长度、宽度和保卫细胞叶绿体数目以及花粉粒大小。结果表明,气孔器长度、宽度和保卫细胞叶绿体数目以及花粉粒大小均与染色体数目和倍性存在正相关关系,可作为鉴定木槿属植物倍性的参考指标。扶桑及其3个栽培变种的花粉粒大小都有较大的变化范围,探讨了这种现象与木槿属植物多倍体起源的关系。     

Delayed autonomous self-pollination in Hibiscus laevis (Malvaceae)

Delayed autonomous self-pollination allows outcrossing to occur while also ensuring that seeds are produced in the absence of pollen vectors. We investigated variation in the efficacy of this pollination mechanism in populations of Hibiscus laevis. Recurvature of stylar branches occurred after 1 d of anthesis, and in plants from Ohio, Illinois, Arkansas, and Oklahoma this behavior resulted in autonomous selfing (surprisingly, stylar movement was facultative in that it did not take place when the stigmas were already pollinated). In contrast to these more northern populations, the distance between anthers and stigmas was too great to allow autonomous selfing in plants from Texas, Mississippi, and Louisiana. Greenhouse studies of plants from Ohio demonstrated that autonomous selfing resulted in an average of 29.5 seeds per flower, as compared to 59.9 seeds per flower from hand-pollination of stigmas with self pollen. In an assessment of the possible significance of this selfing mode, emasculated flowers did not set significantly fewer seeds in a natural stand in Ohio, suggesting that few seeds resulted from autonomous selfing at that site. Modest inbreeding depression was detected at this population. Our results suggest that delayed autonomous selfing is more common in northern populations, where it may facilitate population establishment and persistence at times when pollinators are scarce.     

Developmental- and stress-mediated expression analysis of cinnamoyl-CoA reductase 1 (CCR1) from Hibiscus cannabinus

Cinnamoyl-CoA reductase (CCR, EC 1.2.1.44) is an important enzyme responsible for lignin biosynthesis in plants that belongs to the family of oxidoreductases. We analyzed developmental, tissue specific, and stress-mediated expression of the HcCCR1 (HM151381) gene from Hibiscus cannabinus. Gene expression analysis revealed that HcCCR1 was highly upregulated in mature leaves of 16-week-old plants. The maximum downregulation and upregulation of HcCCR1 was caused by cold and MeJA treatment, respectively. Sequence analysis demonstrated that HcCCR1 protein (ADK24219) contains a conserved NWYCYGK catalytic domain, while bioinformatics prediction indicated the presence of a palmitoylation site in the HcCCR1 protein. Phylogenetic analysis showed that HcCCR1 is more closely related to HcCCR2 (AGJ84130) and AtCCR proteins than CCR-like proteins. Comparative sequence analysis showed presence of significant differences between HcCCR1 and HcCCR2, which are homologs of H. cannabinus. Expression analysis demonstrated that the HcCCR1 gene is modulated by different external stresses.     

Sooty Mould on Hibiscus rosa‐sinensis Caused by Leptoxyphium kurandae is Associated with Extrafloral Nectaries

In August 2013, sooty mould was observed on Chinese hibiscus (Hibiscus rosa‐sinensis) in a propagation nursery in Seoul, Korea. The sooty mould initially developed at the junction between the leaf blade and leaf petiole and then dispersed along the vein on the abaxial surface. The fungal growth pattern on the plants was quite different from general sooty moulds growing on honeydew secreted by insects on the plants. On the basis of the morphological characteristics and phylogenetic analysis using the internal transcribed spacer rDNA, this fungus was identified as Leptoxyphium kurandae. A pathogenicity test was carried out to fulfil Koch's postulates. Through field observation and a pathogenicity test, we found an association between the sooty mould and extrafloral nectaries. To our knowledge, this is the first report of sooty mould caused by L. kurandae on the extrafloral nectaries of H. rosa‐sinensis.     

Effect of potassium on drought resistance of Hibiscus rosa-sinensis cv. Leprechaun: Plant growth,leaf macro- and micronutrient content and root longevity

As competition for the limited water supply available for irrigation of horticultural crops increases, research into crop management practices that enhance drought resistance, plant water-use efficiency and plant growth when water supply is limited has become increasingly essential. This experiment was conducted to determine the effect of potassium (K) nutritional status on the drought resistance of Hibiscus rosa-sinensis L. cv. Leprechaun (Hibiscus). All the treatments were fertilized with Hoagland's nutrient solution, modified to supply K as K₂SO₄, at 0 mM K (K₀), 2.5 mM K (K_2.5), and 10 mM K (K₁₀), under two irrigation regimes (drought stressed [DS] and non-drought stressed [non-DS]). Regular irrigation and fertigation were adopted for 54 days, and drought stress treatment (initiated on day 55) lasted for 21 days; while non-DS control plants continued to receive regular irrigation and fertigation. Following the 21-day drought stress period, plants were labeled with ⁸⁶Rb⁺ to determine the percentage of post-drought stress live roots. Both K deficiency (K₀) and drought stress reduced shoot growth, but drought stress increased root growth and thus the root:shoot ratio. At K₀, plants were K-deficient and had the lowest leaf K, Fe, Mn, Zn, Cu, B, Mo and Al, and highest Ca concentrations. Although the percentage of live roots was decreased by drought stress, K_2.5 and K₁₀ plants (with similar percent live roots) had greater root survival ratio after drought treatment than the K-deficient plants. These observations indicate that adequate K nutrition can improve drought resistance and root longevity in Hibiscus rosa-sinensis.     

Extrafloral nectar of Hibiscus cannabinus promotes adult populations of Harmonia axyridis

High numbers of Harmonia axyridis adults were observed even when aphid populations were low or absent in kenaf (Hibiscus cannabinus) fields. Compared to a control group given access to water alone or cotton aphids and water, longevity of H. axyridis adults provided with kenaf leaves containing extrafloral nectar significantly increased.     

Biochemical and RAPD Analysis of Hibiscus rosa sinensis Induced by Heavy Metals

The present study was designed to assess the effects of three different metals (cadmium, lead, and zinc) at the same concentrations on Hibiscus rosa sinensis during metal uptake. The effects of different metals at the same concentrations were assessed on biomass, root-shoot length, and biochemical parameters like chlorophyll and antioxidant enzymes like SOD and CAT to establish the tolerance potential and toxic effects on plants in different metals. The accumulation of metals by plants was found to be in the following order: Zn > mixed metals > Cd > Pb, where Zn was accumulated approximately 79.6% in plant tissues. Plants removed from Cd showed more enzyme activities than the other two metals. DNA stability was investigated by a Random Amplified Polymorphic DNA (RAPD) technique, which demonstrated that the samples in Cd and mixed metal showed similar trends, whereas samples in Zn and Pb showed similar band intensity to the control. Results suggested that Cd and/or heavy metal stress influences antioxidant status and also induces DNA changes during remediation. Therefore, these studies could be a useful biomarker assay for better treatment for metals’ remediation from soil by means of phytoremediation.     

In vitro culture of callus tissues and cell suspensions from okra (Hibiscus esculentus L.) and cotton (gossypium hirsutum L.)

Summary Methods are described for starting and maintaining callus-tissue cultures of twoMalvaceae, okra (Hibiscus esculentus L.) and cotton (Gossypium hirsutum L.). Okra callus was slow to initiate, but once started it was easy to maintain, in contrast to cotton, which was difficult to initiate and grow. Different media were required to establish the two species. The inclusion of 5 mg per liter of ascorbic acid aided in reducing the formation of black pigments in cotton callus. Hypocotyls of sterile young okra seedlings and leaves of cotton plants were used to produce the callus tissue. Rapidly growing cell suspensions of okra and cotton were obtained in B5 medium.     

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.     

Hibiscus chlorotic ringspot virus p27 and its isoforms affect symptom expression and potentiate virus movement in kenaf (Hibiscus cannabinus L.)

Hibiscus chlorotic ringspot virus (HCRSV), a member of the genus Carmovirus, encodes p27 (27-kDa protein) and two other in-frame isoforms (p25 and p22.5) that are coterminal at the carboxyl end. Only p27, which initiates at the 2570CUG codon, was detected in transfected kenaf (Hibiscus cannabinus L.) protoplasts through fusion to a Flag tag at either its N or C terminus. Subcellular localization of a p27-green fluorescent fusion protein in kenaf epidermal cells showed that it was localized to membrane structures close to cell walls. To study the functions of these proteins, a number of start codon mutants and premature translation termination mutants were constructed. Phenotypic differences were observed between the wild-type virus and these mutants during infection. Infectivity assays on plants indicated that p27 is a determinant of symptom severity. Without p25, appearance of symptoms on systemically infected kenaf leaves was delayed by 4 to 8 days. In a timecourse analysis, Western blot assays revealed that the delay corresponded to retardation in virus systemic movement, which suggested that p25 is probably involved in virus systemic movement. Mutations disrupting expression of p22.5 did not affect symptoms or virus movement.     

Prevailing insects in Roselle plants,Hibiscus sabdariffa L., and their efficiency on pollination

Field surveys of Roselle plant fields were conducted during two successive seasons of 2006 and 2007. The total counted insects on Roselle, Hibiscus sabdariffa attained 16 species belong to seven insect Orders [(Hemiptera (3 species), Homoptera (1 species), Lepidoptera (3 species), Neuroptera (1 species), Coleoptera (3 species), Diptera (1 species), Hymenoptera (4 species)]. Variable numbers of insects were counted on different Roselle varieties and in the two seasons. The most prevailing insect species were the piercing sucking pests [Empoasca spp.; Spilostethus longulus Dallas; Nezara viridula L. and Oxycarenus hyalinipennis (Costa)] and the predators [Polistes sp., Coccinella undecimpunctata and Scymnus syriacus]. Honeybee (Apis mellifera L.) proved to be the most abundant pollinator, averaging 13, 17, 18 individuals/25double strikes in cultivations of Sudani, Masri and White varieties of Roselle plants during flowering of the first season respectively. Similar results were also obtained in the second season. The highest number of honeybees was recorded around 10 am to midday during the flowering stage for the two seasons. It was obvious that the effects of the two hydrothermal, factors temperature and relative humidity, had slight or negligible effects on the occurrence of insect pollination throughout the two seasons of the study, while statistical analysis of the obtained results showed that the productivity of Roselle plant (mean number of seeds and mean weights of seeds) were significantly affected by pollinators.