In Vitro Regeneration of Bamboo Species

This review paper discussed about journals related to micropropagation of bamboo species. In recent years, the application of tissue culture technique like in vitro micropropagation has been used to meet the demands for bamboo products. In the past 30 years, protocols for micropropagation of various bamboo species have been established by researchers from all over the world. The controlling factors for cultures such as the explants, culture medium, carbon sources, combination and concentration of plant growth regulators and other additional additives are varied amongst. The controlling factors are crucial in developing successful regeneration protocols for various bamboo species. This paper is attempted to review and summarize the available and up to date information regarding in vitro micropropagation of bamboos

In vitro regeneration of Acacia crassicarpa A. Cunn Ex benth through organogenesis from juvenile sources

Micropropagation through tissue culture technique offers an alternative to traditional vegetative propagation to mass propagate selected trees for large-scale forest plantation. Therefore, this study aimed to develop a protocol for the micropropagation of A. crassicarpa. Nodal stem segment and leaf obtained from 2 month-old aseptically germinated seedlings were used as explant in this study. Nodal stem segment was found to be the most appropriate explant for shoot formation when cultured on a MS medium supplemented with 6-benzylaminopurine (BAP). The highest mean number of shoots (5) and the longest mean shoot elongation (8 mm) occurred on a medium supplemented with 0.5 mg l-1 BAP. The longest mean shoot length (8 mm) and the highest mean number of explants per culture (7) were obtained on medium without any plant growth regulator. When cultured on a medium supplemented with 2,4-dichlorophenoxy acetic acid (2,4-D), nodal stem segment explant developed roots and callus (after 14 days). The highest mean number of roots (8.3 = 8) and the longest mean root length (12.0 = 12 mm) were obtained from the medium supplemented with 10.0 and 2.0 mg l-1 2,4-D, respectively. The highest mean number of roots (20.6 = 21) and the longest mean root length (10.4 = 10 mm) were obtained from the medium supplemented with 10.0 and 2.0 mgl-1 2,4-D, respectively, while the highest intensity of callus was produced on a medium supplemented with 8.0 and 10.0 mg l-1 2,4-D, and which was only able to produce root without any shoot formation. The calli produced were compact, watery and white in colour. Survival rate of plantlets was higher (100%) when transferred into the autoclaved mixture of soil, sand and peat (3:3:1) than those transplanted in an unautoclaved soil mixture (6.6%). Survival percentages of the plantlets in the culture room and greenhouse condition were 85 and 100%, respectively

In vitro regeneration of bamboo species

This review paper discussed about journals related to micropropagation of bamboo species. In recent years, the application of tissue culture technique like in vitro micropropagation has been used to meet the demands for bamboo products. In the past 30 years, protocols for micropropagation of various bamboo species have been established by researchers from all over the world. The controlling factors for cultures such as the explants, culture medium, carbon sources, combination and concentration of plant growth regulators and other additional additives are varied amongst. The controlling factors are crucial in developing successful regeneration protocols for various bamboo species. This paper is attempted to review and summarize the available and up to date information regarding in vitro micropropagation of bamboos

Multiple shoot induction of selected genotypes of Eucalyptus camaldulensis Dehn

The increasing demand of Eucalyptus camaldulensis for its multipurpose values has called forth efforts to produce improved materials of this tree species. Here we study the effects of plant growth regulators (PGRs) on multiple shoot induction and develop a protocol for a workable micropropagation of improved selected genotype of E. camaldulensis Dehn. Shoot tips and nodal segments initiated from meristematic region were cultured on Murashige and Skoog (MS) basal medium containing six concentrations of cytokinin i.e. 1.0, 1.5, 2.0, 2.5, 3.0 and 3.5 mgL-1 of 6-Benzylaminopurine (BAP) plus 0.1 mgL-1 of auxin i.e. α-Naphthalene Acetic Acid (NAA) or Indole Butyric Acid (IBA). Maximum mean shoot length (8.11mm) and mean shoot number (5.01) were obtained from shoot tips after four weeks of culture compared to the mean shoot length (7.73 mm) and mean number of shoots (4.75) from nodal segments. The best growth in terms of mean shoot length (11.83 mm) and mean number of roots (9.10) was obtained with a combination of 3.0 mgL-1 of BAP and 0.1 mgL-1 of NAA. Protocol developed in this present study can assist in the large scale plantation of E.camaldulensis in future

In Vitro micropropagation of Acacia auriculiformis from selected juvenile sources

The effects of 6- Benzylaminopurine (BA), different basal medium, sucrose concentration and gelling agent were investigated for shoot induction and multiplication of Acacia auriculiformis. Nodal ex¬plants derived from 5-month-old seedlings yielded the highest shoot multiplication rate in Murashige and Skoog medium (MS) with 0.44 μM BA, 30 g/L sucrose and 2 g/L Gelrite. The highest mean number of shoots (10) and mean length of shoots (5.07mm) were also obtained in this medium. Qualitative obser¬vation of the shoots cultured in 0.44 μM BA were greener and vigorous in growth as compared to shoots cultured on higher concentrations of BA (22.2 μM). MS medium produced a significantly higher number of shoots (18) compared to Woody Plant Medium (WPM) (11) and B5 medium (10). Media solidified with different gelling agents also produced a significantly different number of shoots with 2 g/L Gelrite produced the highest number of shoots (23). The highest percentage of shoots rooted was found in the MS medium without any growth regulators (40.0%) followed by medium supplemented with Indole-3-bu¬tyric acid (IBA) at 9.84 μM and the combination of 9.84 μM IBA with 5.37 μM α-naphthalene acetic acid (NAA) (33.3%). MS medium without any plant growth regulators produced the highest mean root length (84.33mm), whereas medium supplemented with 9.84 μM IBA produced the highest mean number of roots per shoot (4.33). Out planting of in vitro rooted shoots in shredded coconut husk as the substrate gave the highest percentage of survival (90%) during acclimatization in the greenhouse

Gibberellic acid (GA3) affects growth and development of some selected kenaf (Hibiscus cannabinus L.) cultivars

Kenaf (Hibiscus cannabinus L.), is a potential alternative of natural wood fibers for biocomposite and pulp and paper industry. However, the average fiber length of kenaf is usually shorter than the critical length to be used for high quality biocomposite materials. Increasing fiber length and quality can diversify its application in fiber based industries. Gibberellic acid (GA3) is an important plant growth regulator that is actively involved in cell elongation and other important physiological functions in plant growth, development and flowering. To investigate the effects of gibberellin on growth, morphology, and fiber quality, some selected cultivars of kenaf plants were treated with aqueous solution of varying concentrations of GA3. The effects on vegetative and reproductive growth were evaluated weekly for sixteen consecutive weeks and fiber morphology after harvesting at 18th week. Gibberellin treatment significantly reduced the vegetative growth in terms of stem diameter, leaf number, and leaf size but stimulated fiber elongation, resulted in a tall and slender plant with curled leaves. Gibberellin treatment also impaired reproductive growth by inhibiting floral initiation and development in all treated plants whereas the control plants were in its seed harvesting stage. This study provided novel insights into the effects of GA3 in regulating vegetative and reproductive growth of kenaf as well as improving its fiber properties

Genetic variation and clonal propagation of superior genotypes of selected Acacia species

The Acacia species was introduced into Malaysia in the late 1960’s for timber production. Plantations of Acacia species gain interest as a major timber species in the 1960’s especially in Peninsular Malaysia along with Hevea brasiliensis. The product in forestry ventures is often sawn timber, which requires trees to be in good conditions such as straight, single-stemmed and defect-free trunks for maximum utilization. Production of such quality wood is another big problem in forestry plantation since trees grown in plantation of some high-value temperate and tropical hardwood species tend to produce low value, short butt logs and bolts due to crooked stems, low fork heights and delayed shedding of lower branches. In this context, a research study was initiated to select and recommend the best performing tree species or provenances suited for timber production in Malaysia with respect to growth and other characteristics. Species/provenance/progeny test was conducted on four species of Acacia namely, A.mangium, A.auriculiformis, A.crassicarpa and A. aulococarpa with four provenances for each species from two main regions of Papua New Guinea and Queensland. The growth of the provenances was monitored in terms of some quantitative and qualitative characteristics to evaluate the genetic variation and growth performance of a base breeding population. The study showed that there were significant differences (p< 0.05) between species, provenance and progenies for their growth performance. There were also significant differences between provenances within regions and progenies within provenances in all quantitative and qualitative traits tested in this study. Generally, with regard to the growth, A.mangium performs better compared to other Acacia species in all of the aspects tested and it was followed by A.crassicarpa, A.aulococarpa and A.auriculiformis. Generally provenances and progenies selected from Papua New Guinea excelled those from Queensland both in quantitative and qualitative characteristics. Among the top performing progenies of Acacia species are CG 1854 of (Bensbach WP) and KN000107 (SW of Boset WP) of A.mangium, BVG2609 (Bensbach WP) of A.crassicarpa, BVG 00835 (WP Morehead) and MM1016 (Arufi E Morehead WP) of A.aulococarpa and JSL363 (Wenlock River) and BVG 2657 (Bansbach) of A.auriculiformis. Three best performing clone (genotypes) were then chosen based on their phenotypic characteristic for clonal propagation of superior tree species through traditional and modern techniques. Vegetative propagation was attempted as initial pretreatment stage of rejuvenation of mature sources through forced flushing, stem cuttings and trunk decapitation. A. mangium and A. auriculiformis respond well to force flushing by having highest survival percentage (87.7% and 90%, respectively) together with bud breaking and sprout growth. Whereas, A.aulococarpa and A.crassicarpa only recorded 52.2% and 31.1% of survival percentage. Rooting ability of stem cuttings, feasible and mean root number and root length increase at juvenile stage for all species studied. Rooting ability of mature cuttings decreased and bud breaks occurred only for few days eventually died, and did not respond to the treatments of growth regulators. Rooting ability of young stem cuttings of A. mangium (83.3%) and A.auriculiformis (76.6%) was better compared to that of A.crassicarpa and A aulococarpa with only 48% and 68.8%, respectively. Investigation was also done for the use of coppice materials as an alternative source for in vitro propagation of mature sources. 12 yearold trees of selected Acacia species were felled to the height of 1.0m and 1.5m. Vigorous production of sprout or coppice was noted on the stumps of trees of all species except of A.crassicarpa. The greatest copping ability in terms of survival rate of stumps was observed on A.auriculiformis with 83.8% followed by, A.mangium, A.aulococarpa and A.crassicarpa with 75.0%, 40.0% and 1.67 %, respectively. A.crassicarpa produces a very low number of sprouts with mean of 0.03 and mean of 0.09 for sprout length. Rejuvenated mature explants were further subjected to in vitro conditions for mass production of improved materials for establishment of efficient in vitro protocol for Acacia sp. Decontamination of field collected materials was conducted as an initial stage in shoot initiation stage using some methods optimized in preliminary study. Most effective sterilization in term of average clean culture percentage (>70%) was recorded in 0.1% HgCl2 for 5 minutes for A.mangium, A.auriculiformis, A.mangium ‘Superbulk’ and A. hybrid and 0.1% HgCl2 for 10 minutes for both A.crassicarpa and A.aulococarpa. Incorporation of 0.1g/l of fungicide Benomyl with 50mg/ml of antibiotic streptomycin further enhanced the survival rate and percentage of clean culture up to 80%-100%. Multiple shoot production was obtained from all species of Acacia on Murashige and Skoog (MS) medium supplemented with 2.0 mg/l benzyladenine (BA) plus 0.5 mg/l of NAA. It was also noted that greater shoot production occurred with combination of plant growth regulators with additives. The maximum shoot number and shoot length was produced in medium supplemented with 2.0 mgl-1 benzyladenine (BA) + 0.5 mgl-1 of NAA + activated charcoal (0.1% w/v) combined with 100 mgl-1 AdSO4. It produced maximum number of 9.0 shoots per explant with 3.51 cm in length. Shoots were then elongated and rooted in an optimized condition and further acclimatized to nursery condition.Another study was initiated to evaluate and identify sequence markers which gave phylogenetic information to be used to infer relationship within Acacias at a fine level. Primer designed based on second intron of LEAFY gene of A.mangium amplified the specific region with single band except for A. hybrid. The amplified regions were sequenced to reveal the species relationship within selected Acacias. Result revealed that non coding region of the second intron of LEAFY gene is more variable and can be used as marker for phylogenetic studies at lower taxanomic levels

Stimulation of multiple leader formation in some genotypes of Acacia mangium and Acacia auriculiformis with 6-Benzylaminopurine (BAP)

Acacia mangium Willd. and Acacia auriculiformis A. Cunn. ex. Benth. are two of the fast-growing tropical acacias which have received priority for genetic assessment and improvement. They were therefore proposed for timber production in a short rotation in Malaysia but were impeded by the multiple leaders (ML) formation which limited their value as sawn timber. This work attempts to investigate the causes of ML formation in four genotypes of A. mangium and A. auriculiformis as related to apical dominance, nutrition and plant growth hormones and their correlations. The effects of 6-benzylaminopurine and decapitation on ML formation of these genotypes were also investigated. 6-benzylaminopurine (BAP) as a foliar spray and also decapitation did not stimulate ML formation. However, they significantly increased the number of branches and reduced all other growth traits including height. However, basal diameter was not affected by decapitation. The effects of BAP increased consistently with increasing level of application. BAP at 1500 mg·L-1 resulted in mortality of A. mangium provenances while A. auriculiformis provenances survived and grew normally. Some of the BAP treated plants of both species developed juvenile pinnate leaves. Decapitation of the apical bud resulted in the activation of the lateral bud immediately below the point of decapitation

Improved Clonal Propagation through Rejuvenation of Mature Branch Cutting of Four Important Acacia Species

Asexual propagation techniques for producing good quality germplasm for breeding and dissemination purposes have proven difficult for acacia species comprised of mature planting material. The study was conducted to study the effect of rejuvenation on the rooting ability of mature cuttings. Shoots were induced from the lower branch by cutting a part of the mature branch of the crown and leaving it horizontally on the propagation bench under the misting system. Shoots were harvested and further used as stem cuttings to evaluate their rooting ability through the application of rooting hormone. The rooting ability of the cuttings is highly variable among species. The percentage of stem sections producing juvenile shoots was similar for Acacia mangium Willd. (88%) and Acacia auriculiformis A.Cunn. ex Benth. (90%). Only 52% of stem sections were able to produce shoots for Acacia crassicarpa A.Cunn. ex Benth., followed by Acacia aulococarpa A.Cunn. ex Benth. with only 31%. Overall, A. auriculiformis rooted better and recorded the highest mean value for all traits tested. Hormone treatment significantly enhances the rooting ability of A. auriculiformis and A. mangium. However, A. aulococarpa and A. crassicarpa did not respond well to the treatment. Rejuvenated stem cuttings were rooted better than mature cuttings, producing the highest mean value for all traits tested in all species, with or without hormone treatment. Results indicated that it is possible to rejuvenate mature cuttings through bud break in a controlled environment

Overexpression of Arabidopsis thaliana gibberellic acid 20 oxidase (AtGA20ox) gene enhance the vegetative growth and fiber quality in kenaf (Hibiscus cannabinus L.) plants

Kenaf (Hibiscus cannabinus L.; Family: Malvaceae), is multipurpose crop, one of the potential alternatives of natural fiber for biocomposite materials. Longer fiber and higher cellulose contents are required for good quality biocomposite materials. However, average length of kenaf fiber (2.6 mm in bast and 1.28 mm in whole plant) is below the critical length (4 mm) for biocomposite production. Present study describes whether fiber length and cellulose content of kenaf plants could be enhanced by increasing GA biosynthesis in plants by overexpressing Arabidopsis thaliana Gibberellic Acid 20 oxidase (AtGA20ox) gene. AtGA20ox gene with intron was overexpressed in kenaf plants under the control of double CaMV 35S promoter, followed by in planta transformation into V36 and G4 varieties of kenaf. The lines with higher levels of bioactive GA (0.3–1.52 ng g−1 fresh weight) were further characterized for their morphological and biochemical traits including vegetative and reproductive growth, fiber dimension and chemical composition. Positive impact of increased gibberellins on biochemical composition, fiber dimension and their derivative values were demonstrated in some lines of transgenic kenaf including increased cellulose content (91%), fiber length and quality but it still requires further study to confirm the critical level of this particular bioactive GA in transgenic plants