Species Of Haworthia Research Articles

Effects of light intensity and plant growth regulators on callus proliferation and shoot regeneration in the ornamental succulent Haworthia

BackgroundHaworthia are desert succulents belonging to the Asphodelaceae family. Haworthia species are cultivated commercially as ornamentals and some rare species are quite valuable at retail market but growth slowly and difficult to propagation. However, an efficient micropropagation protocol was remained insufficient.ResultsThe organogenic cultures obtained from inflorescence explants were cultured on Murashige and Skoog (MS) medium supplemented with various combinations of 6-benzylaminopurine (BA) and α-naphthalene acetic acid (NAA) under a light intensity of 10 μmol m−2 s−1 or 45 μmol m−2 s−1. The highest callus proliferation index (93.15%) with 1.0 mg L−1 BA + 0.1 mg L−1 NAA under a light intensity of 10 μmol m−2 s−1. The best shoot proliferation rates were on media with either 1 mg L−1 BA + 0–0.4 mg L−1 NAA (65.57–81.01%) under a light intensity of 45 μmol m−2 s−1. The highest root length (15.57 mm) and the highest rooting frequency (17 roots per shoot) were obtained when adventitious shoots were inoculated on MS medium with 0.4 mg L−1 NAA + 0.4 mg L−1 IBA. The survival rate of the transplanted plantlets was about 100%. The efficient micropropagation protocol proliferated Haworthia regenerate plants from inflorescence within 11 weeks.ConclusionsThe present study determined the best combination of light intensity and plant growth regulators (PGRs) for improved organogenesis of Haworthia during propagation by tissue culture. This optimized protocol showed light intensity is an important factor for efficient callus or shoot regeneration. These results indicate that it will be useful to optimize the light conditions for future commercial cultivation, germplasm conservation, genetic engineering and molecular biology research of this ornamental plant.

Species-specific response to acute hyperthermal stress of Haworthia (Asphodelaceae) plants

An increase in environmental temperature is one of the most common stress factors for plant organisms. The study of the plants’ adaptation to stress factors remains extremely important and relevant. This article presents the results of a acute short-term influence of hyperthermia on species of two subgenera of the genus Haworthia Duval. We investigated the different levels of antioxidant protection and damage degree of the members of two subgenera of the genus Haworthia at the biochemical level, measuring the lipid peroxidation, superoxide dismutase and peroxidase activities, total flavonoid content and content of photosynthetic pigments with a spectrophotometer. To determine the drought tolerance of plants, the water supply of tissues, water shortage and loss of water after an hour of wilting were measured. The values for different groups were compared by ANOVA followed by the Tukey multiple comparison test. The studied plants were warmed in a thermostat at temperatures of 40 °C and 50 °C for three hours under the conditions of natural light. The control group of plants was kept at 25 °C. The research has shown that H. attenuata, H. limifolia and H. cymbiformis are characterized with the increase of concentration of malonic dialdehyde at 40 °C and 50 °C, but a significant difference of values wasn’t received,which indicates the relative resistance of these plants to the influence of high temperatures. The sharp increase of temperature causes the highest level of lipid peroxidation in H. parksiana plants, along with which, warming to 50 °C launches a mechanism of activation and synthesis of superoxide dismutase and flavonoids for the plants. The studied species of the subgenus Haworthia have a photosynthetic system relatively resistant to thermal stress in comparison to the subgenus Hexangulares. H. limifolia plants have a slight inhibition of photosynthesis. The adaptation of H. cymbiformis to thermal stress is due to the strategy of accumulation of a pool of active enzymes, superoxide dismutase, peroxidase, flavonoids under normal conditions and the activation of new peroxidase enzymes as a result of stress. H. attenuata is characterized by activation of new enzymes of superoxide dismutase and peroxidase under stress. It was found that H. cymbiformis and H. attenuata are more heat resistant in comparison with the other two species. Acute short-term hyperthermia has a different influence on the antioxidant system of different species of Haworthia. H. limifolia has the highest drought tolerance, H. cymbiformis has the lowest, the other two species from different subgenera have similar drought tolerance indicators. We did not find any dependence of the mechanisms of action of the antioxidant system under hyperthermia on the type of adaptation to arid conditions at the anatomical level in plants of different subgenera of the genus Haworthia.

A synoptic review and new infrageneric classification for the genus Haworthiopsis (Xanthorrhoeaceae: Asphodeloideae)

Haworthiopsis was established in 2013 to accommodate the species formerly classified under the subgenus Hexangulares of the genus Haworthia. This new genus is near-endemic to South Africa and found in most of the provinces of the country. It is also known from southern Namibia, Swaziland and possibly Mozambique. A total of 18 species are currently recognised in Haworthiopsis. However, this circumscription renders the genus paraphyletic with H. koelmaniorum sister to a polytomy comprising the rest of the Haworthiopsis taxa and Gasteria. In this contribution, seven new combinations are published (H. fasciata var. browniana, H. reinwardtii var. reinwardtii f. chalumnensis, H. reinwardtii var. reinwardtii f. kaffirdriftensis, H. reinwardtii var. reinwardtii f. olivacea, H. tessellata var. crausii, H. viscosa, H. scabra var. smitii) and two changes of status (H. koelmaniorum var. mcmurtryi, H. viscosa var. variabilis). An amplified description of the genus is provided. Six sections formerly recognised under Haworthia (subg. Hexangulares) are applied and adapted to Haworthiopsis, with some amendments. A new section, H. sect. Koelmaniorum, is described here. New combinations for hybrid taxa in Haworthiopsis that were previously described as species of Haworthia are given.

A Molecular Phylogeny and Generic Classification of Asphodelaceae subfamily Alooideae: A Final Resolution of the Prickly Issue of Polyphyly in the Alooids?

Abstract Phylogenetic analysis of plastid (rbcLa, matK, trnH-psbA and the trnL intron) and nuclear (ITS1) sequence datasets in a wide sampling of species of Asphodelaceae: Alooideae provides a generally well-resolved phylogeny. Among traditionally accepted genera only Astroloba and Gasteria are supported as monophyletic. Species of Haworthia are distributed among three clades corresponding to the current subgenera. Aloe s. l. (including Chortolirion) segregates into six, well-supported clades corresponding respectively to sections Dracoaloe (= Aloidendron), Kumara + Haemanthifoliae, Macrifoliae, Aristatae, Serrulatae, and the remainder of the genus. The first three clades are retrieved as early branching lineages, whereas A. sects. Aristatae and Serrulatae are strongly supported as members of a clade including Astroloba + Haworthia subg. Robustipedunculatae. We examine possible options for recircumscribing the genera of Alooideae as reciprocally monophyletic entities. Although morphological and molecular ...

Karyomorphology of three species of Haworthia Duval (Xanthorrhoeaceae)

Karyomorphological studies were carried on three species of Haworthia Duval (family: Xanthorrhoeaceae) namely H. radula (Haw.) Duval, H. glauca Bak.var. herrei and H. limifolia Marl.var. keithii. Karyotyping through Image Analyzing System in three species of Haworthia (family: Xanthorrhoeaceae) reflected karyotypic orthoselection with same basic chromosome number (x = 7) and bimodal karyotype. In H. radula (2n = 14) two satellites were found one in each on the long arm of the two long chromosomes. H. glauca var. herrei and H. limifolia var. keithii possessed 2n = 28 somatic chromosomes. In addition pollen mitosis of each species was done. Pollens are endowed with expected number of n = 7 and bimodal chromosomes. Therefore karyotyping through Image Analyzing System suggests that H. radula is diploid (2n = 14) whereas H. glauca var. herrei and H. limifolia var. keithii are autotetraploid (2n = 28) plants.

Revisiting monophyly in Haworthia Duval (Asphodelaceae): Incongruence, hybridization and contemporary speciation

AbstractMolecular phylogenetic reconstructions have indicated that Haworthia is not monophyletic. Here we show, using considerably expanded datasets of both chloroplast (trnL‐trnF and psbA‐trnH intergenic spacers) and nuclear (ITS1) markers that the issue of a polyphyletic Haworthia is more complicated than previously reported. Both parsimony and bayesian analyses of cpDNA and ITS1 produced poorly resolved phylogenies, with little or no support for deeper nodes. Species of Haworthia are placed in three of the four main lineages in the cpDNA phylogeny, while in the ITS1 phylogeny Haworthia species were placed in two of the four main lineages retrieved. The cpDNA phylogeny was incongruent with that obtained from the ITS1 data, and the topology of the combined dataset reflected that obtained from the ITS1 dataset. As species of H. subg. Hexangulares and subg. Robustipedunculares have been reportedly involved in intergeneric hybridizations with other Alooideae, it is postulated that a history of ancient hybridization may account for a polyphyletic Haworthia. Hybridization is also ongoing between species within H. subg. Haworthia, and may be responsible for results indicating that some species in this subgenus are not monophyletic. This hybridization may be facilitated by the lack of effective reproductive barriers. We hypothesize that Haworthia is undergoing a contemporary and explosive radiation in southern Africa, driven in part by local adaptation to relatively fine‐grained ecological heterogeneity of soils and microclimate.

General applicability of in vitro storage technology to the conservation and maintenance of plant germplasm

The broad applicability of in vitro storage technology to the preservation of germplasm for agriculture, horticulture, forestry, biotechnologically based industries and the conservation of plants that are endangered forms the basis of this contribution. In order for this technology to be implemented it is necessary to have efficient and reliable micropropagatory procedures for the species under question. The development of both sets of procedures are discussed for cassava, Eucalyptus and two endangered indigenous Haworthia species. In each case storage is required for different reasons and the versatility of the in vitro storage technology in satisfying the requirements is highlighted

A new species of Haworthia (Asphodelaceae) - H. venusta

Summary: A new species of Haworthia from the Eastern Cape is described as H. venusta. Its closest ally seems to be H. joeyae C.L. Scott and the points of difference are noted.

Establishment of Aloe, Gasteria, and Haworthia Shoot Cultures from Inflorescence Explants

Shoot cultures of Aloe, Gasteria, and Haworthia species were initiated directly from immature inflorescences. Explants placed on a modified MS medium containing 5.4 mm zeatin riboside initiated shoots within 8 to 12 weeks. Long-term shoot cultures were established and maintained on media containing either 5.4 μm zeatin riboside or 4 μm BA. Shoots easily rooted in vitro, and rooted plantlets were esablished in soil. Chemical names used: N-(phenylmethyl)-1H-purin-6-amine (BA); 6-[4-hydroxy-3-methyl-but-2-enylamino]purine riboside (zeatin riboside).

A new species of Haworthia (Asphodelaceae) - H. joeyae

A new species of Haworthia from the False Central Lower Karoo, a few kilometres north east of Cookhouse in the Eastern Cape, is described as H. joeyae. Its closest allies are H. altilinea Haw. and H. pilifera Bak. and the points of difference are noted.

A new species of Haworthia (Asphodelaceae) - H. pringlei

A new species of Haworthia from near Adelaide in the Eastern Cape is described as H. pringlei. Its closest ally is H. xiphiophylla, and the points of difference are noted. Not more than 80 specimens remain in the only known population in habitat.

Optimization of plant regeneration and rooting from leaf explants of five rare Haworthia

Five rare Haworthia species, desirable as attractive ornamentals, were cultured in vitro to define conditions for a reliable cloning system. Adventitious buds were regenerated from leaf explants of Haworthia retusa cultivar ‘Dekenahii’, Haworthia retusa cultivar ‘Giant Form’, Haworthia emelyae cultivar ‘Sandkraal’, Haworthia mirabilis cultivar ‘Mundula’, and Haworthia mutica. Optimum cytokinin type (kinetin or BA) and concentration for shoot regeneration and growth was in the range of 1–2 mg l −1 and differed relative to the genotype tested. Lower levels of cytokinin caused increased shoot length while more numerous, but tiny, shoots were produced at levels higher than optimum. Shoots rooted in vitro in vermiculite plus liquid medium had superior root number and length compared with those rooted in vermiculite moistened with water or in gelled medium. No period of high humidity was needed to acclimatize shoots rooted in vermiculite plus medium ex vitro. No somaclonal variation was observed. This system may be applicable to other Haworthia species for multiplication of rare genotypes.

Shoot temperatures and thermal tolerances for succulent species of Haworthia and Lithops

Abstract. Temperatures of small succulent plants, such as species in the genera Haworthia and Lithops, are highly influenced by temperatures of the surrounding soil. Indeed, the minimum and the maximum temperatures of the upper leaf epidermis of Haworthia retusa. H. turgida. Lithops leslei, and L. turbiniformis were generally within 1°C of the accompanying soil surface temperatures. An energybudget model closely predicted such soil‐to‐plant temperature differences as well as the effect of the greater convective exchange for the protruding Haworthia species compared with the Lithops species, which were flush with the soil surface. Although a lower shortwave absorptance would reduce maximum shoot temperatures, the shortwave absorptances of all four species were similar to those of the soil in their respective native habitats in South Africa. Tolerances of the four species to low and to high temperatures at three different day/night air temperatures (15°C/5°C, 30°C/20°C, and 45°C/35°C) were analysed using cellular accumulation of a vital stain, neutral red. Chlorenchyma cells were slightly more tolerant of extreme temperatures than were cells of the water‐storage parenchyma. In this regard, H. retusa survived low and high temperatures that killed the water‐storage parenchyma but not the chlorenchyma. Acclimation to low temperatures and to high temperatures, which was exhibited by all four species, led to estimated tolerances to 1 h at −16°C and 68°C. Although the low temperature tolerance is not particularly noteworthy, very few vascular plants are reportedly able to tolerate such high temperatures.

Callus characteristics and classification of Haworthia and allied genera

More than 500 plants, including all species and varieties of Haworthia, Astroloba, Poellnitzia, Chortolirion, and 23 species of Aloe, were cultured in vitro. Most of them produced calli and indirect adventitious shoots. Callus character changed in successive subcultures, and four common stages of callus development were recognized. Generally, callus characteristics were noted in the early stages of culture, and these corresponded closely with the taxonomic affinity of the species. In general, calli of the subgenus Haworthia were soft and white, grew easily and produced numerous shoots. Plants of the subgenus Hexangulares were difficult to culture in vitro, and their calli were brownish in colour. Calli of the subgenus Robustipedunculares, genera Astroloba and Poellnitzia resembled each other, and were very ciliate and difficult to subculture. Callus of Chortolirion resembled that of the subgenus Haworthia. Aloe produced bright yellow calli with many thick roots, these results differing greatly from all other taxa investigated. In the light of callus features, Haworthia species were classified into 20 species groups and eight sections under three subgenera. It was suggested that Astroloba may be a species group of Haworthia, and Chortolirion may be a ‘pseudo-bulb’ Aloe such as A. kniphofioides. Callus characteristics, therefore, appear to be of value in the classification of Haworthia and allied genera.

Tissue culture inHaworthia

Effects of three auxins and kinetin on growth of the calluses of two species ofHaworthia, H. aristala andH. setata, were investigated. Stock calluses derived from the flower buds of these species were maintained for two years on RM-1964 agar medium containing 5 mg/l NAA. Small pieces of the stock calluses were transferred to the basal medium containing either auxin, IAA, NAA or 2,4-D in six different concentrations (0.1–50 mg/l) combined with three concentrations (0–2 mg/l) of kinetin; in total, 54 kinds of media were used. Fresh weight of the calluses was measured 0 to 30 days from transfer and transformed to the natural logarithm. The linearity of their growth curves against the culture period was tested. The growth curves of theH. aristata calluses grown in dark and under continuous light and that of theH. setata callus grown in dark gave similar regression coefficients of 0.07 to 0.11, indicating that the doubling time of the callus mass was about 6.3 to 10.1 days.After 42 to 50 days from inoculation, the fresh weight of each individual callus was recorded, and the data were statistically analyzed. All auxins at the concentration of 50 mg/l significantly inhibited callus growth. Kinetin did not affect growth of theH. aristata callus in dark, while its effect on theH. setata callus was detected under light. Interaction of kinetin was found with IAA and 2,4-D inH. aristata and with IAA and NAA inH. setata. REsponses of theH. aristata callus to auxins and kinetin, when grown in dark, were different in several points from those of theH. setata callus grown under light. The best callus growth was observed in the following media; 0.2 mg/l kinetin supplemented with 1 mg/l IAA, or 0.5 mg/l 2,4-D, and 2 mg/l kinetin with 0.5 mg/l NAA inH. aristata, and 0.2 mg/l kinetin supplemented with 1 mg/l IAA, 5 mg/l NAA or 0.1 mg/l 2,4-D inH. setata.

Using Haworthia Cultured Cells as an Aid in Teaching Botany

IDUCTION OF TISSUE CULTURES from monocotyledons for morphogenetic studies in the developmental botany or advanced botany laboratory is a problem often faced by many instructors and students. This is because information on monocotyledons tissue culture is limited (Shimada et al. 1969). The recent introduction of a technique to induce callus cultures from several species of the genus Haworthia offers a suitable method to study monocotyledon cell morphogenesis in vitro (Majumdar and Sabharwal 1968; Majumdar 1970a, 1970b, 1970c). The genus Haworthia a member of the tribe Aloineae and family Liliaceae, is a common succulent native to the South African region. (Haworthia species may be obtained from the International Succulent Institute of Millbrae, California, USA.) It is found in many greenhouses, homes, and biological supply houses in the United States (fig. 1). The species are easily maintained in the laboratory, and they flower several times a year. The cytogenetics of Haworthia is well known (Majumdar and Riley 1973). Recently, calluses induced from Haworthia on culture media have been used to study morphogenesis and to observe the effects of mutagens and carcinogens on chromosomes, cells, and cell organelles (Kaul and Sabharwal 1975; Majumdar and Schlosser 1971; Majumdar and Newton 1972; Sullender and Majumdar 1975). The species are also suitable for plant developmental studies since the time required for callus induction on defined media is very short-two to three weeks. Vegetative bud production and subsequent differentiation of the callus into roots and leafy shoots can be obtained in 'five to six weeks after initial inoculation. In our research we have successfully induced callus cultures from flower axes, flowers, and ovary walls from several species of Haworthia.

Morphogenetic Studies on Haworthia: Establishment of Tissue Culture and Control of Differentiation

Investigations were carried out on the in vitro morphogenetic responses of inflorescence segments and gynoecia of several species of Haworthia (Liliaceae). Morphogenetic responses of explants were not species specific. It was found that coconut milk was essential for the growth and differentiation of Haworthia tissue if White's basal medium was used. However, growth and differentiation could be supported by a modified Murashige and Skoog's medium, without any supplements. The investigations demonstrated’ the importance of inositol and ammonium nitrogen in the nutrition of Haworthia tissue cultures. A chemical control of callusing and shoot and root differentiation was obtained by providing appropriate amounts of auxin and cytokinin in the culture medium.

MORPHOGENETIC STUDIES ON HAWORTHIA: ESTABLISHMENT OF TISSUE CULTURE AND CONTROL OF DIFFERENTIATION

Investigations were carried out on the in vitro morphogenetic responses of inflorescence segments and gynoecia of several species of Haworthia (Liliaceae). Morphogenetic responses of explants were not species specific. It was found that coconut milk was essential for the growth and differentiation of Haworthia tissue if White's basal medium was used. However, growth and differentiation could be supported by a modified Murashige and Skoog's medium, without any supplements. The investigations demonstrated’ the importance of inositol and ammonium nitrogen in the nutrition of Haworthia tissue cultures. A chemical control of callusing and shoot and root differentiation was obtained by providing appropriate amounts of auxin and cytokinin in the culture medium.