multiple shoots in vitro, which were subsequently used as explants to establish somatic embryogenesis in B. edulis Munro ( Lin et al., 2004 ). This method could provide the healthy plantlets without any seasonal limitations. Unlike B. edulis , in our
Choun-Sea Lin, Krishnan Kalpana, Wei-Chin Chang, and Na-Sheng Lin
Guochen Yang and Marihelen Kamp-Glass
Multiple shoots were produced directly from each explant. BA, zeatin, or TDZ were evaluated on callus initiation, development, and shoot organogenesis. Callus production was promoted when BA or zeatin was added in culture medium. However, no shoots were produced from such calli. Multiple shoots were produced directly through shoot organogenesis from each seed explant when TDZ was added to culture medium. As many as 30 to 40 shoots were produced per seed explant in about 7 weeks from culture initiation. Different alfalfa cultivars were also tested. The established multiple shoot production protocol provides an efficient way to produce transgenic alfalfa plants, thus could significantly advance alfalfa genetic transformation.
Ramana M. Gosukonda, C.S. Prakash, and Ananta Porobo Dessai
Studies were conducted to improve adventitious shoot regeneration in sweetpotato [Ipomoea batatas (L.) Lam.], specifically to extend the protocol to many genotypes and to elicit production of multiple shoots per explant. The use of a two-stage procedure where excised petioles were incubated on Murashige and Skoog (MS) (1962) medium with 2,4-D (0.2 mg·liter–1) for 3 days and transferred to a second medium containing MS salts with thidiazuron and 2iP (0.05 mg·liter–1 each) resulted in shoot regeneration from eight of 13 genotypes tested, including elite sweetpotato cultivars such as `Jewel' and `Rojoblanco'. PI 318846-3 was the most regenerable genotype, with up to 77% of explants producing one to three shoots per explant. The orientation of the petiole on the nutrient medium was critical; those placed vertically inverted developed multiple shoots. Wounding explants through epidermal peeling with normal horizontal orientation of the explants during incubation also resulted in multiple shoot production (about three shoots per explant). Interference with auxin transport due to explant inversion or wounding may have stimulated increased shoot induction. Chemical names used: 2,4 dichlorophenoxyacetic acid (2,4-D); N-phenyl-N′-1,2,3-thiadiazol-5-ylurea (thidiazuron); N 6-(2-isopentenyl) adenine (2iP).
C. C. Pasian and J. H. Lieth
The main objective of this project was to develop a crop simulation model for greenhouse cut flower roses. An intermediate step towards the completion of that objective is the building of a model for the growth and development of a collection of shoots of various ages throughout the canopy. The canopy is represented as ten 20 cm thick layers. The shoot and leaves (age and location) are tracked as they grow into and through these layers using a model developed previously. Leaf area (LA) and leaf area index (LAI) for each layer is computed. A light distribution submodel, based on cumulative LAI, estimates the amount of radiation intercepted by each leaf. It is assumed that multiple shoots originating the same day from the same layer are identical. The model also simulates the effect of harvest of the shoots in the canopy. Currently, work is proceeding on data collection for prediction of carbohydrate partitioning within the canopy. Future work will focus on model validation.
Karsedis Distabanjong and Robert L. Geneve
Somatic embryos from Eastern redbud show a high degree of malformation during development and a low conversion rate to seedlings. This problem is common with somatic embryo systems, especially with legume species. A procedure for multiple shoot formation from somatic embryo explants of Eastern redbud was developed that bypasses the need for germination to recover plantlets. Somatic embryo explants cultured on DKW medium containing benzyladenine (BA) and thidiazuron (TDZ) produced more shoots than either treatment alone. The highest number of shoots (3.3 to 3.4 shoots per explant) was obtained from partially desiccated and wounded explants treated with a combination of 5 or 10 M BA and 0.5 or 1.0 M TDZ for 20 days before being transferred to the same medium without TDZ. The number of shoots formed was increased from 1.5 to 3.2 shoots per explant by cutting through the cotyledonary node prior to culture. In addition, the frequency of explants forming shoots was increased by desiccation of somatic embryo explants to ≈50% moisture and by using somatic embryos with two well-formed cotyledons as explants.
E. D. Earle and R. W. Langhans
Small (0.5 mm high) shoot tips of Chrysanthemum morifolium ‘Giant #4 Indianapolis White’ were grown on Murashige-Skoog medium containing various levels of kinetin, NAA, and GA3. Formation of roots, single or multiple shoots, plantlets and friable, hard or leafy callus depended on the hormone levels used. Multiple shoots and green leafy callus were produced on medium containing 2.0 mg/l kinetin and 0.02 mg/l NAA. The leafy callus was suitable for subculture and subsequent reorganization of plantlets. Multiple shoots were rooted and grown into normal plants or were used to start new cultures which formed more multiple shoots. This technique will be useful for storage and propagation of Chrysanthemum and especially for detection and rapid multiplication of virus-free plants.
Muhammad Irshad, Hafiz Muhammad Rizwan, Biswojit Debnath, Muhammad Anwar, Min Li, Shuang Liu, Bizhu He, and Dongliang Qiu
al., 2010 ; Kabir et al., 2008 ). Direct organogenesis is a good alternative regeneration method to attain multiple shoot production. This method has less somaclonal variation, is less time consuming ( Yildirim and Turker, 2014 ), and has a greater
Gilbert L.J. Samyn
T.K. Liew and C.K.H. Teo
Axillary buds from 5-month-old seedlings of Azadirachta excelsa Linn. were surface-sterilized twice with 1.35% (m/v) and 1.05% (m/v) of sodium hypochlorite for 25 and 15 minutes, respectively, before culturing on Murashige and Skoog (MS) medium containing combinations of BA and NAA. A combination of 4.4 μM BA + 0.5 μM NAA induced the most axillary buds to grow (eight per explant). Subsequent proliferation of the micropropagated shoots on this medium yielded abnormal shoots. The best medium for maximum proliferation of these micropropagated shoots contained 3.3 μM BA and 0.27 μM NAA. On this medium about four normal shoots were produced per explant. These findings indicate that two different media are needed for successful micropropagation of sentang. Chemical names used: N 6-benzylaminopurine (BA); 1-naphthaleneacetic acid (NAA).
Carrie A. Radcliffe, James M. Affolter, and Hazel Y. Wetzstein
georgia plume have been made, yet conventional techniques have not been effective. Propagation by shoot cuttings has been unsuccessful, and root cuttings can produce only a limited number of shoots ( Fordham, 1991 ). Scanty population numbers and lack of