Comparative analysis of diversification and population structure of kenaf (Hibiscus cannabinus L.) and roselle (H. sabdariffa L.) using SSR and RGA (resistance gene analogue) markers

Multiple DNA marker systems and complementary analytical approaches are often useful in population genetic analysis and speciation of plants. We investigated population structure of kenaf (Hibiscus cannabinus) and roselle (H. sabdariffa) for gaining insight in evolution and geographic separation of these crop species using SSR and RGA (resistance gene analogues) markers through Bayesian clustering and principal coordinate analysis (PCoA) methods. Genotyping by 12 SSR and 16 RGA markers amplified a total of 172 loci in the study population. The RGA markers generated higher number of alleles per marker (8.2) as compared to SSR (3.4), but exhibited lower heterozygosity in the population. Genetic variance and heterozygosity in roselle population for both marker systems were lower than in kenaf. RGA markers revealed higher variation among populations. Bayesian structure as well as PCoA analysis using RGA marker revealed distinct cluster for roselle, while SSR-based classification revealed high admixture. Results indicate geographic isolation and natural selection for adaptive RGA alleles in kenaf. The Indian kenaf landraces were distinct from the exotic kenaf accessions, suggesting separate lineage formation by geographic separation. Possible origin and domestication of roselle in South India is proposed.     

Interspecific hybrids between kenaf ( Hibiscus cannabinus ) and roselle ( H. sabdariffa )

The successful interspecific cross is reported for the first time between kenaf (Hibiscus cannabinus L.), a diploid species (2n=36) and roselle (Hibiscus sabdariffa L.), a tetraploid species (2n=72). Kenaf, grown for its bast fiber and also under investigation as a source of paper pulp, is fast-growing and well adapted to mechanical harvesting, but susceptible to root-knot nematodes. Roselle, also grown for its bast fiber, is slower growing, not well adapted to mechanical harvesting, but certain varieties are resistant to root-knot nematodes. Five hybrid plants were produced from the pollination of 4,445 flowers of kenaf with pollen from roselle; no hybrid plants were produced from 2,655 pollinations made in the reciprocal direction. One line of roselle was the parent of 3 of the 5 hybrids; one line of kenaf was the parent of 2 of these 3. The F₁ hybrids were triploid, and varied in vigor, growth habit and vegetative morphology, but had similar flowers. Two of the F₁ hybrids showed high pollen fertility, apparently as a result of restitution at first meiotic division leading to unreduced spores. These two hybrids each produced a small amount of seed, which gave rise to an F₂ population of 22 plants. The F₂ plants vary in vigor but are morphologically uniform, have thick leaves with mosaic sectors, and are presumably spontaneous allohexaploids. The theoretical possibilities of increasing the percentage of recovery of the F₁ interspecific hybrids and of developing a synthesized hybrid variety useful for bast fiber and paper pulp are discussed. Research done cooperatively by Crops Research Division and Agricultural Engineering Research Division, Agricultural Research Service, U.S. Department of Agriculture (USDA), and the University of Florida Agricultural Experiment Station. Cytological investigations were carried out at the Department of Biological Sciences, Florida State University. Thanks are extended to the many individuals and organizations who supplied material for this study, and to M. Griffin Bell and E. Otho Richey, Agricultural Research Technicians, for their enthusiastic assistance.     

Assessment of molecular diversity and evolutionary relationship of kenaf (Hibiscus cannabinus L.), roselle (H. sabdariffa L.) and their wild relatives

Kenaf (Hibiscus cannabinus L.) and roselle (H. sabdariffa L.) are valuable fibre crop species with diverse end use. Phylogenetic relationship of 73 accessions of kenaf, roselle and their wild relatives from 15 countries was assessed using 44 inter-simple sequence repeat (ISSR) and jute (Corchorus olitorius L.) specific simple sequence repeats (SSR) markers. A total of 113 alleles were identified of which 61.95 % were polymorphic. Jute specific SSR markers exhibited high polymorphism and resolving power in kenaf, although ISSR markers exhibited higher resolving power than SSR markers. Number of polymorphic alleles varied from 1 to 5 for ISSR and 1 to 6 for SSR markers. Cultivated species exhibited higher allele polymorphism (57 %) than the wild species (35 %), but the improved cultivars exhibited lower genetic diversity compared to germplasm accessions. Accessions with common genetic lineage and geographical distribution clustered together. Indian kenaf varieties were distinct from cultivars bred in other countries and shared more genetic homology with African accessions. High genetic diversity was observed in the Indian (J = 0.35–0.74) and exotic kenaf germplasm collections (J = 0.38–0.79), suggesting kenaf might have been introduced in India from Africa through Central Asia during early domestication. Genetic similarity-based cluster analysis was in close accordance with taxonomic classification of Hibiscus.     

Phytoextraction of As and Fe using Hibiscus cannabinus L. from soil polluted with landfill leachate

Terrestrial plants as potential phytoremediators for remediation of surface soil contaminated with toxic metals have gained attention in clean-up technologies. The potential of kenaf (Hibiscus cannabinus L.) to offer a cost-effective mechanism to remediate Fe and As from landfill leachate-contaminated soil was investigated. Pot experiment employing soil polluted with treatments of Jeram landfill leachate was conducted for 120 days. Plants were harvested after 8th, 12th, and 16th weeks of growth. Accumulation of Fe and As was assessed based on Bioconcentration Factor and Translocation Factor. Results showed sequestration of 0.06-0.58 mg As and 66.82-461.71 mg Fe per g plant dry weight in kenaf root, which implies that kenaf root can be an bioavailable sink for toxic metals. Insignificant amount of Fe and As was observed in the aerial plant parts (< 12% of total bioavailable metals). The ability of kenaf to tolerate these metals and avoid phytotoxicity could be attributed to the stabilization of the metals in the roots and hence reduction of toxic metal mobility (TF < 1). With the application of leachate, kenaf was also found to have higher biomass and subsequently recorded 11% higher bioaccumulation capacity, indicating its suitability for phytoextraction of leachate contaminated sites.     

Characterization and Cytopathology of Hibiscus Latent Ringspot Virus Isolated from Kenaf (Hibiscus cannabinus L.) in Italy

Hibiscus latent ringspot virus (HLRV) was isolated from kenaf plants (Hibiscus cannabinus L.) in Italy. and identified as III. RV by its host range, purification, electron microscopy and serology. Ultrastructural studies showed that infected plants contained membranous cytoplasmic inclusion bodies. characteristic of nepoviruses, and sometimes also crystalline aggregates.     

红麻(Hibiscus cannabinus L.)种质资源的鉴定与分类研究

对300份野生红麻和337份栽培红麻的形态学鉴定发现,红麻的茎、叶、花、果等植物学性状的类型多样,差异明显,遗传多样性十分丰富。野生红麻和栽培红麻一样,染色体数为2n=36,同属红麻种（Hibiscus cannabinus L．）;核型有2n=36=32M＋2SM＋2M（SAT）、2n=36=34M＋2M（SAT）和2n=36=32M＋2ST＋2M（SAT）等;综合形态学研究结果,将野生红麻分为普通、多毛、螺旋花和扁圆果4种类型,其中普通型又可分为3个亚类,普通型与栽培红麻亲缘关系最近,并发现红麻存在亚种。栽培红麻可分为9个变种17个类型,其中4个为新发现变种,7个为新发现类型。     

Control of Meloidogyne javanica and M. arenaria on kenaf and roselle with genetic resistance and nematicides

Kenaf (Hibiscus cannabinus) and roselle (H. sabdarifla) were evaluated in nematicide-treated and untreated field soil naturally infested with either Meloidogyne javanica or M. arenaria. Root-knot indices indicated that the kenaf breeding line j-l-113 had moderate resistance to M. javanica and low resistance to M. arenaria. Kenaf cv Everglades 71 was highly susceptible to both M. javanica and M. arenaria, and roselle breeding line A59-56 was highly resistant. Both nematode species reproduced on all plant entries, but more larvae were recovered from the soil in plots planted to Everglades 71 than in plots planted to j-l-l13 or A59-56. In untreated soil infested with M. javanica, dry-matter yields were greater (P = 0.05) for j-l-l13 and A59-56 than for Everglades 71. The percentages of live plants at harvest were: j-l-l13, 88; A59-56, 93; and Everglades 71, 9. Ethylene dibromide (1,2-dibromoethane) at 73.9 kg a.i./ha and DBCP (1,2-dibromo-3-chloropropane) at 17.6 kg a.i./ha increased dry-matter yields significantly for all entries planted in soil infested with M. arenaria. Carbofuran (2.3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) at 5.9 kg a.i./ha did not increase the dry-matter yields of any entry. None of the nematicides increased the growth of any entry significantly in soil infested with M. javanica.     

Photosynthesis and kinetic characteristics of rubisco in Hibiscus cannabinus L

Photosynthetic characteristics in kenaf (Hibiscus cannabinus L.), a C3 plant, were compared with Abelmoschus esculentus (L.) Moench, another member of Malvaceae. Kenaf leaves exhibited significantly higher rate of photosynthesis (40 mg CO2 dm(-2) hr(-1)) which was 24.6 mg dm(-2) hr(-1) in A. esculentus. Rate of photo and dark respiration was similar in both the species. Kenaf leaf photosynthesis had a higher optimum temperature (32 degrees C) than that of A. esculentus (26 degrees C). Photosynthesis in kenaf leaves required higher saturation irradiance (1,600 micromole m(-2) sec(-1)). There was a significant correlation between photosynthetic rate and biomass yield in these species. The primary product of photosynthesis after 5 seconds of 14C-assimilation was 3-PGA in both the species. The kinetic properties of RuBP carboxylase/oxygenase were determined in the leaf extracts. Higher carboxylase activities were recorded with kenaf leaf extracts (245 pmole mg chl(-1) hr(-1)). Km (CO2) for kenaf leaf carboxylase was significantly lower (7.8 microM) than A. esculentus (13.5 microM) and corresponding difference in Vmax values of carboxylase was recorded between the two species. The kinetic characteristics of oxygenase were similar in both the extracts. These results indicated the variation in carboxylase activity and its kinetic characteristics reflected a significant difference in CO2 assimilation in C3 plants.     

Comparative studies of genetic diversity in kenaf (Hibiscus cannabinus L.) varieties based on analysis of agronomic and RAPD data

Kenaf (Hibiscus cannabinus L.) is a fiber crop classified in the genus Hibiscus (Malvaceae), and has a great potential for its multipurpose utilization, in addition to its traditional usage. Varietal identification of kenaf is always problematic and knowledge on genetic diversity of kenaf varieties is also limited, which significantly hindered our effective utilization and conservation of the valuable kenaf germplasm. In order to find a proper method for identifying kenaf varieties and studying their variation, morpho-agronomic characters and random amplified polymorphic DNA (RAPD) markers were analyzed among 14 kenaf varieties commonly used in Japan. Data from morphological analysis showed that the included kenaf varieties could be divided into three major groups. The characters, such as middle stem diameter, whole stalk weight, and days to 50% flowering, are highly responsible for the variation of the kenaf varieties, but it is difficult to identify individual varieties merely by the morpho-agronomic characters. On the other hand, clearly separation of the kenaf varieties was achieved based on the RAPD variation patterns. Genetic relationship of the kenaf varieties can also be traced through the analysis of RAPD and morph-agronomic variation. It is concluded from the present study that RAPD analysis is an effective tool in identifying of kenaf varieties and determining their genetic relationships, particularly when combined with the analysis of morpho-agronomic characters.     

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.     

Genetic Diversity of Kenaf (Hibiscus cannabinus) Evaluated by Inter-Simple Sequence Repeat (ISSR)

Understanding genetic diversity is very useful for scientific utilization for breeding. In this study, we estimated the genetic distances in a panel of 84 kenaf accessions collected from 26 countries and regions using ISSR markers. The results of UPGMA analysis showed that kenaf germplasm had abundant genetic variation, with genetic dissimilarity coefficients ranging from 0.01 to 0.62. The in-group dissimilarity coefficient (0.29) was observed in 84 kenaf accessions, and all the accessions could be divided into three groups: cultivars (L_1–1), relatively wild species (L_1–2 and L_1–3), and wild species (the others). Further in-group analysis in group L_1–1 (0.19) revealed that the kenaf cultivars could be divided into five subgroups with distinct regional characteristics. It is imperative that genes be exchanged among all kinds of tested varieties from different origins. The results provide a useful basis for kenaf germplasm research and breeding.     

Potential of kenaf (Hibiscus cannabinus L.) and corn (Zea mays L.) for phytoremediation of dredging sludge contaminated by trace metals

The potential of kenaf (Hibiscus cannabinus L.) and corn (Zea mays L.) for accumulation of cadmium and zinc was investigated. Plants have been grown in lysimetres containing dredging sludge, a substratum naturally rich in trace metals. Biomass production was determined. Sludge and water percolating from lysimeters were analyzed by atomic absorption spectrometry. No visible symptoms of toxicity were observed during the three- month culture. Kenaf and corn tolerate trace metals content in sludge. Results showed that Zn and Cd were found in corn and kenaf shoots at different levels, 2.49 mg/kg of Cd and 82.5 mg/kg of Zn in kenaf shoots and 2.1 mg/kg of Cd and 10.19 mg/kg in corn shoots. Quantities of extracted trace metals showed that decontamination of Zn and Cd polluted substrates is possible by corn and kenaf crops. Tolerance and bioaccumulation factors indicated that both species could be used in phytoremediation.     

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。     

Variation of morphological and phytochemical traits in Roselle (Hibiscus sabdariffa L.) genotypes under different planting dates

Roselle (Hibiscus sabdariffa L.) is recognized as a valuable food crop due to its nutraceutical potential, rich pigment content, and medicinal properties. However, there is limited information on planting dates and suitable genotypes for roselle cultivation in arid and semi-arid regions. The objective of this field study was to investigate the influence of five planting dates (March, April, May, June, and July) on morphological and phytochemical characteristics of different roselle genotypes. Among genotypes, eight (Jiroft, Dalgan, Bampoor, Iranshahr, Nikshahr, Roodbar, Saravan, and Qaleganj) were Iranian landraces, and HA and HS-24 were originated from Ghana and Bangladesh, respectively. Planting date significantly influenced the number of branches, bolls and seeds per plant, sepal fresh weight, calyx and biomass yields, and harvest index in tested roselle landraces. The greatest morphological growth, fresh sepal weight (50.6 g plant^?1) and calyx yield (1519 kg ha^?1) were observed with the roselle planted in early May. Moreover, amounts of chlorophyll, flavonoids and antioxidant remained higher in roselle when planted between April–May. The number of branches/plant was found to be an important determinant of calyx yield (r = 0.707) in roselle. Dalgan resulted in the greatest growth and yields within a comparatively shorter period of time compared to other tested landraces. Both principal component analysis (PCA) and cluster analysis also indicated that Dalgan landrace possessed most suitable morphological and phytochemical traits among tested landraces, and therefore, it could be planted adopted for extensive cultivation settings in the arid and semi-arid regions.     

<Emphasis Type="Italic">CaMi</Emphasis>, a root-knot nematode resistance gene from hot pepper (<Emphasis Type="Italic">Capsium annuum</Emphasis> L.) confers nematode resistance in tomato

Several root-knot nematode (Meloidogyne spp.) resistance genes have been discovered in different pepper (Capsium annuum L.) lines; however, none of them has yet been cloned. In this study, a candidate root-knot nematode resistance gene (designated as CaMi) was isolated from the resistant pepper line PR 205 by degenerate PCR amplification combined with the RACE technique. Expression profiling analysis revealed that this gene was highly expressed in roots, leaves, and flowers and expressed at a lower level in stems and was not detectable in fruits. To verify the function of CaMi, a sense vector containing the genomic DNA spanning the full coding region of CaMi was constructed and transferred into root-knot nematode susceptible tomato plants. Sixteen transgenic plants carrying one to five copies of T-DNA inserts were generated from two nematode susceptible tomato cultivars. RT-PCR analysis revealed that the expression levels of CaMi gene varied in different transgenic plants. Nematode assays showed that the resistance to root-knot nematodes was significantly improved in some transgenic lines compared to untransformed susceptible plants, and that the resistance was inheritable. Ultrastructure analysis showed that nematodes led to the formation of galls or root knots in the susceptible lines while in the resistant transgenic plants, the CaMi gene triggered a hypersensitive response (HR) as well as many necrotic cells around nematodes. Rugang Chen and Hanxia Li are contributed equally to this work.     

Relative resistance of transgenic tomato tissues expressing high levels of tobacco anionic peroxidase to different insect species.

Different parts of genetically transformed tomato (Lycopersicon esculentum L.) plants that express the tobacco anionic peroxidase were compared for insect resistance with corresponding wild type plants. Leaf feeding by first instar Helicoverpa zea and Manduca sexta was often significantly reduced on intact transgenic plants and/or leaf disks compared to wild type plants, but the effect could depend on leaf age. Leaves of transgenic plants were generally as susceptible to feeding damage by third instar Helicoverpa zea (Boddie) and Manduca sexta (L.) as wild type plants. Green fruit was equally susceptible to third instar larvae of H. zea in both type plants, but fruit of transgenic plants were more resistant to first instar larvae as indicated by significantly greater mortality. Basal stem sections were more resistant to neonate larvae of H. zea and adults of Carpophilus lugubris Murray compared to wild type plants as indicated by significantly greater mortality and/or reduced feeding damage. Thus, tobacco anionic peroxidase activity can increase plant resistance to insects in tomato, a plant species closely related to the original source plant species, when expressed at sufficiently high levels. However, the degree of resistance is dependent on the size of insect and plant tissue involved.     

Susceptibility of two different strains of Aedes aegypti (Diptera: Culicidae) to plant oils

The toxicity of 11 oils extracted from plants commonly grown in the Himalayan region was studied using larvae of two Aedes aegypti (L.) strains. A strain from Liverpool, England, was highly susceptible to these oils. The LC50 values were much higher in a local laboratory strain. Daucus carota L. oil was highly toxic in both strains. Differences in the susceptibility of these strains to the action of the test oils and their potential use in integrated pest management are discussed.     

Alpha-amylase inhibitors from roselle (Hibiscus sabdariffa Linn.) tea

A roselle (Hibiscus sabdariffa Linn.) tea extract was found to have high inhibitory activity against porcine pancreatic alpha-amylase. Hibiscus acid and its 6-methyl ester were respectively isolated as active principles from the 50% methanol and acetone extracts of roselle tea. The activity of each isolate was compared to that of structurally related citric acid, a previously known inhibitor of fungal alpha-amylase.