Dendrobium Sonia-28 Research Articles

Review of research on Dendrobium sonia-28, a hybrid from Orchidacea family and mutation as somaclonal variation

Review of research on Dendrobium sonia-28, a hybrid from Orchidacea family and mutation as somaclonal variation

Stress Effect and Development of Leaf-Bridge Bioassay of Dendrobium Sonia-28 Orchid Plantlets Resistant to Fusarium Proliferatum

Among horticultural and floral crops, orchids are outstanding in their diversity of shape, form and colour. Dendrobium sonia-28 is an important orchid hybrid in the Malaysian flower industry, but suffers from fungal diseases especially those caused by Fusarium proliferatum . Protocorm-like bodies (PLBs) of Dendrobium sonia-28 were subjected to various doses of Fusarium proliferatum culture filtrate (CF), fusaric acid (FA) and gamma irradiation. Results showed that PLBs survival rate were inversely related to the treatment doses as well as experience time. Another main objective of this study was to evaluate degree of resistance among Dendrobium sonia-28 plantlets derived from PLBs treated with CF, FA and gamma irradiation methods. Plantlets obtained from the various treated PLBs were inoculated with a pathogen spore suspension of 10,000 spore/mL. Leaf-bridge bioassay results revealed that leaflets challenged with higher concentrations of CF, FA and gamma irradiation showed less disease symptoms after treatment, indicating that there is a strong relationship between in vivo and in vitro resistance of Dendrobium sonia-28 to infection to Fusarium proliferatum

Gamma Irradiation-Induced Variation in Dendrobium Sonia-28 OrchidProtocorm-Like Bodies (PLBs)

Dendrobium sonia-28 is an important ornamental orchid in the flower industry. In vitro mutagenesis by means of gamma irradiation can be used to produce economically improved mutants. Protocorm-like bodies (PLBs) of Dendrobium sonia-28 were subjected to gamma irradiation at doses of 10 to 200 Gy gamma rays. Results showed that PLBs survival rate and weight were inversely related to the irradiation doses. In untreated PLBs, survival rate and weight were tenfold and fivefold higher as compared to 200 irradiated PLBs. Results indicated that the radio sensitivity test (LD50) for the PLBs were approximately at 43 Gy. There were appreciable variations in plantlet structure and morphology relative to increase irradiation doses. Plantlets infected with low doses of gamma radiation had better development of the shoot and root as well as the foliage. SEM and TEM analysis disclosed severe surface and cell organelles damage and stomatal closure in protocorm-like bodies (PLBs) infected with the high irradiation dose. Therefore, the findings of this study have proven an efficient method of in vitro mutagenesis through gamma radiation. The results obtained in this study suggested that PLBs survival rate, growth rate percentage, morphological characteristics as well as techniques such as SEM and TEM may be used in early assessment of effectiveness and superiority of radiation dose to induce mutations. Moreover, Some RAPD markers clearly discriminated between selected and non-selected variants of Dendrobium sonia-28, showing different banding patterns for each gamma irradiation doses.

Effects of Melatonin on Colchicine-Treated PLBs of Dendrobium sonia-28 Orchid.

Dendrobium hybrid orchid is popular in orchid commercial industry due to its short life cycle and ability to produce various types of flower colours. This study was conducted to identify the morphological, biochemical and scanning electron microscopy (SEM) analysis in the Dendrobium sonia-28 orchid plants. In this study, 0.05 and 0.075% of colchicine-treated Dendrobium sonia-28 (4-week-old culture) protocorm-like bodies (PLBs) were treated in different concentrations of melatonin (MEL) posttreatments (0, 0.05, 0.1, 0.5, 1, 5 and 10μM). Morphological parameters such as number of shoots, growth index and number of PLBs were determined. In the 0.05 and 0.075% of colchicine-treated PLBs which were posttreated with 0.05μM MEL resulted in the highest value of the morphological parameters tested based on the number of shoots (84.5 and 96.67), growth index (16.94 and 12.15) and number of PLBs (126.5 and 162.33), respectively. SEM analysis of the 0.05μM MEL posttreatment on both the colchicine-treated regenerated PLBs showed irregular cell lineages, and some damages occurred on the stomata. This condition might be due to the effect of plasmolyzing occurred in the cell causing irregular cell lineages.

Effects of fusaric acid treatment on the protocorm-like bodies of Dendrobium sonia-28.

Dendrobium sonia-28 is a popular orchid hybrid due to its flowering recurrence and dense inflorescences. Unfortunately, it is being decimated by fungal diseases, especially those caused by Fusarium proliferatum. In this study, selection of F. proliferatum-tolerant protocorm-like bodies (PLBs) was carried out by assessing the effects of differing concentrations of fusaric acid (FA). PLBs were cultured on Murashige and Skoog (MS) medium supplemented with 0.05 to 0.2millimolar (mM) concentrations of FA. Higher concentrations of FA increased mortality of PLBs and reduced their growth. The survival rate for 0.05mM FA was 20% but only 1% at the highest dose of 0.2mM. Additionally, two different size ranges of PLBs were investigated, and growth increased more at lower FA concentrations for larger PLBs, whilst the growth rate of smaller PLBs was inhibited at an FA concentration of 0.2mM. Histological examination using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses disclosed severe cell wall and organelle damage, as well as stomatal closure in PLBs treated with the high FA concentrations. Reductions in plantlet growth were much greater at the highest concentrations of FA. Some randomly amplified polymorphic DNA (RAPD) markers clearly discriminated between selected and non-selected variants of Dendrobium sonia-28, showing different banding patterns for each FA concentration and specific bands for selected and control plants.

Fusarium proliferatum culture filtrate sensitivity of Dendrobium sonia-28’s PLBs derived regenerated plantlets

Aims: Dendrobium sonia-28 is an important orchid in the Malaysian flower industry and currently facing serious production problems due fungal diseases. To overcome this impediment, one of the strategies being pursued is by the production of new orchid mutants. In this prospect, the present study was aimed to determine effects of Fusarium proliferatum culture filtrate on the potential of producing somaclonal variants Dendrobium sonia-28 plants tolerance to F. proliferatum disease infection. Methodology and results: Here, we assessed Fusarium proliferatum pathogenicity on the survival and fresh weight responses of Dendrobium sonia-28 PLBs using culture filtrate. PLBs death increased at the highest concentrations and resulted in reduced weight among survivors. There were appreciable variations in plantlet structure and morphology relative to increase fungal filtrate concentration. Plantlets infected with lower concentrations of the fungus had better development of the shoot and root as well as the foliage. Histology and SEM analysis disclosed severe cell wall damage and stomatal closure in protocorm-like bodies (PLBs) infected with the higher fungal filtrate concentrations. Conclusion, significance and impact study: As well as giving insights into the clonal reproduction of F. proliferatum, these results emphasizes the significance of somaclonal variation plants production based on low fungal infection tolerance in floriculture technology. Hence, the ability of the Dendrobium sonia-28 to survive after F. proliferatum infection opens new avenues for resistance gene discovery and future development of fungus resistant transgenic orchids.

Efficient micropropagation of Dendrobium sonia-28 for rapid PLBs proliferation

Effective propagation of protocorm-like bodies (PLBs) of Dendrobium sonia-28 was achieved in this study. The highest PLBs proliferation within 21 days was observed in semi-solid media over liquid culture. Half strength of Murashige and Skoog (MS) media produced the highest PLBs growth rate percentage compared to full and double strength MS media in semi-solid culture. In sucrose treatment, the highest increased of PLBs growth rate percentage was in 10g.L-1. PLBs growth rate percentage was the highest (14%) in media devoid of exogenous 6-benzylaminopurine (BAP) or naphthalene acetic acid (NAA). However, the addition of BAP and NAA in combinations of BAP (4.44 or 8.88 µM) and NAA (8.88 µM) resulted in increased PLBs growth rate to 14% compared to when added separately. The optimized micropropagation media and condition of PLBs proliferation are important for the production of large number of plant material required for the development of genetic modification and cryopreservation studies.

Catalase and Superoxide Dismutase Activities and the Total Protein Content of Protocorm-Like Bodies of Dendrobium Sonia-28 Subjected to Vitrification

Dendrobium sonia-28 is an important ornamental orchid in the Malaysian flower industry. However, the genus faces both low germination rates and the risk of producing heterozygous progenies. Cryopreservation is currently the favoured long-term storage method for orchids with propagation problems. Vitrification, a frequently used cryopreservation technique, involves the application of pretreatments and cryoprotectants to protect and recover explants during and after storage in liquid nitrogen. However, cryopreservation may cause osmotic injuries and toxicity to cryopreserved explants from the use of highly concentrated additives, and cellular injuries from thawing, devitrification and ice formation. Reactive oxygen species (ROS), occurring during dehydration and cryopreservation, may also cause membrane damage. Plants possess efficient antioxidant systems such as the superoxide dismutase (SOD) and catalase (CAT) enzymes to scavenge ROS during low temperature stress. In this study, protocorm-like bodies (PLBs) of Dendrobium sonia-28 were assayed for the total protein content, and both SOD and CAT activities, at each stage of a vitrification exercise to observe for deleterious stages in the protocol. The results indicated that cryopreserved PLBs of Dendrobium sonia-28 underwent excessive post-thawing oxidative stress due to decreased levels of the CAT enzyme at the post-thawing recovery stage, which contributed to the poor survival rates of the cryopreserved PLBs.

Cryopreservation of Dendrobium sonia-28 using an alternative method of<br>PVS2 droplet freezing

Dendrobium sonia-28, an ornamental orchid in the Malaysian flower industry, is under risk of producing heterozygous progenies. Cryopreservation is a favoured long-term storage method for orchids with propagation problems. The droplet-freezing technique, utilising the principles of vitrification, has emerged as an important technique in the preservation of various plant species. This study was conducted to optimise the droplet-freezing technique for protocorm-like bodies (PLBs) of Dendrobium sonia-28, with viability tests conducted through the 2,3,5-triphenyltetrazolium chloride assay. The best results were obtained when 1-2 mm PLBs were precultured for 24 hours on half-strength Murashige and Skoog (MS) semi-solid medium supplemented with 0.5 M sucrose, placed in a loading solution for 10 minutes and dehydrated in PVS2 at 0°C for 20 minutes, prior to thawing, unloading in 1.2 M sucrose and recovery on semi-solid recovery medium composed of half-strength MS components and 2% sucrose for three weeks.

Refinement of a vitrification protocol for protocorm-like bodies of Dendrobium sonia-28

The hybrid Dendrobium sonia-28 is an important ornamental orchid in the Malaysian flower industry. However, it faces the risk of producing heterozygous progenies through conventional seed propagation or somaclonal variation. Cryopreservation is a favoured long-term storage method in the preservation and maintenance of orchids with specific desired traits. This paper presents a successful cryopreservation protocol for protocorm-like bodies (PLBs) of Dendrobium sonia-28 through the vitrification technique and the use of ascorbic acid and charcoal. Survival assessments were conducted through growth evaluations and visual and spectrophotometric 2,3,5-triphenyltetrazolium chloride assays. Results of this study, an improvement over the previous protocol applied to this orchid hybrid, showed that the addition of ascorbic acid to the preculture, loading, dehydration, unloading, and regeneration media, coupled with the addition of charcoal to the regeneration medium, helped boost recovery rates of cryopreserved PLBs of Dendrobium sonia-28.

Histology and scanning electron microscopy observations of cryopreserved protocorm-like bodies of Dendrobium sonia-28

The genus Dendrobium possesses horticultural importance. Dendrobium sonia-28 is an important ornamental orchid in the flower industry. Cryopreservation is a favoured long-term storage method for orchids with propagation problems. Protocorm-like bodies (PLBs) of Dendrobium sonia-28 were cryopreserved using the vitrification technique. Histology and scanning electron microscopy (SEM) observations were conducted on stock, non-cryopreserved (control), and cryopreserved PLBs of Dendrobium sonia-28 to detect cryoinjuries resulting from the vitrification protocol. Histological observations of control PLBs indicated that the preculture, osmoprotection, and dehydration steps were not physically damaging to the PLBs. Histological and SEM analyses of cryopreserved PLBs indicated that the freezing and thawing cycles inflicted damages on the parenchymatic regions of the PLBs. Only embryogenic cells survived the treatment. Scanning electron microscopy studies of the control and cryopreserved PLBs indicated that both osmotic and freezing injuries occurred only in the interior regions of the PLBs.

Biochemical and histological changes in Dendrobium sonia-28 protocorm-like bodies (PLBs) at various low temperatures and under mineral oil layer

The study was conducted on the storage of Dendrobium sonia-28 protocorm-like bodies (PLBs) at various temperatures (5, 10, 15, 20, and 25°C) and under mineral oil layer. Biochemical analyses were conducted on the PLBs by determining thechlorophyll, total soluble protein and peroxidase activities. In addition, histological analyses of cell structure, rate of survival and shoot growth after the recovery process were carried out. This study was performed in two conditions; three (3) weeks and twelve (12) days of growth recovery period after 3 weeks of storage treatment. The PLBs were transferred to half strength Murashige and Skoog (MS) medium containing 1.0 mg/L benzylaminopurine (BAP) and kept at 25±2°C for twelve (12) days during recovery period. Overall, PLBs stored under 5°C and mineral oil layer produced the lowest values in chlorophyll analysis, rate of survival and shoot growth. However, total soluble protein content was increased during twelve (12) days of growth recovery period. Histological analysis has shown that the cell structure of these PLBs sustained a high degree of damage due to the treatment. PLBs stored under 5°C and mineral oil layer recorded the highest peroxidase activity attributed to higher stress conditions. Key words: Dendrobium sonia-28, PLBs, low temperature, mineral oil, biochemical analysis.