Multiple shoot induction in zygotic embryos: A strategy for acceleration of banana breeding

The presence of residual female fertility in most of the parthenocarpic banana accessions, embryo culture technique encourages the banana breeder to develop new hybrids through conventional breeding. Desirable trait can be fixed in banana in the first generation of hybrid progenies, but their evaluation is a long process owing to non-availability of uniform suckers/planting material. The duration of the breeding cycle can be reduced by developing more number of plantlets per hybrid event under in vitro embryo culture. Thus efforts were taken to standardize the multiple shoot formation from single embryo through media manipulation and decortications of embryo culture derived single plants. Success on multiple shoot formation was achieved up to 75% and 95% in seeded accessions of M.acuminata and M.velutina embryos respectively. In general, enhanced regeneration efficiency and rate of multiple shoot formation were recorded in media with BAP concentration of 17.76µm. Single in vitro plantlets derived through embryo culture were decorticated to 3 cubic cm size that resulted in 100% multiple shoot formations. This technique has been implemented from the seeds obtained from controlled pollination (18 cross combinations) and open pollination (nine accessions) of various genomic groups (ABB, AAB, AA) and their genetic fidelity of multiple shoots were also confirmed through microsatellite markers. As this technique, i) enhances the regeneration of hybrid seeds; ii) overcomes the risk of field mortality of the hybrid progenies and iii) allows simultaneous evaluation for multiple traits, will accelerate the breeding program by reducing the time taken for the release of potential banana hybrids.

Propagación in vitro de especies de Echinocereus, Escontria, Mammillaria, Melocactus y Polaskia (Cactaceae)

In vitro propagation systems by means of areole activation were developed for Echinocereus knippelianus, Echinocereus schmollii, Mammillaria carmenae, M. carmenae fo. rubrisprina, M. herrerae, M. theresae, Melocactus curvispinus, Escontria chiotilla and Polaskia chichipe. In vitro germinated seedlings were used as source of explants. Multiple shoot formation from areoles was achieved on MS basal medium supplemented with 3% sucrose, 10 g L-1 agar and 6-benzylaminopurine (BA) or 6-(, -dimethylallylamino)purine (2iP). Efficiencies ranged from 6.0 shoots per explant in M. carmenae fo. rubrisprina to 13.5 shoots per explant in Echinocereus schmollii. Rooting of the in vitro generated shoots was achieved in MS basal medium, or MS basal medium supplemented with indoleacetic acid, indolebutyric acid or activated charcoal. Finally, 49-98% of these plants survived.

Efficient Direct Organogenesis from Shoot Tips and Nodal Segments of Ash Gourd (Benincasa Hispida L.)

The effect of external application of phytohormone on explants viz., shoot tips and nodal segments of ash gourd (Benincasa hispida L.) was tested on the frequency of shoot and root induction. Shoot tips and nodal segments were cultured on MS medium supplemented with different concentrations and combinations of cytokinins (BAP, Kinetin), auxin (IBA, NAA) and gibberellic acid (GA3) for multiple shoot formation and root induction. The highest number (up to 90%) of multiple shoot formation was obtained from the shoot tips in MS medium fortified with 1.5 mg/l BAP + 0.2 mg/l GA3, where average number of shoots per culture was 5.55. In case of nodal segment, better response (up to 78%) for shoot multiplication was found in MS with 2.0 mg/l BAP + 0.2 mg/l GA3. The concentration of 1.0 mg/l IBA was found to be most effective for root initiation in microshoot developed from both types of explants. Rooted plantlets were acclimatatized and established in sandy soil with good survival rate DOI: http://dx.doi.org/10.3329/jles.v8i0.20135 J. Life Earth Sci., Vol. 8: 17-20, 2013

Study of Shoot Multiplication of Strawberry (Fragaria ananassa)

Effects of different hormonal concentration on multiple shoot formation of RABI Strawberry-3 were studied. Where the explants were runner tips that cultured on MS basal medium supplemented with 6-Benzyl Adenine and Kinetin. The maximum percentage 80% of shoot was obtained from Benzyl Adenine concentrations of 0.5 mg/l and 1.0 mg/l whereas Kinetin concentrations were 1.5 mg/l and 2.0 mg/l separately. More promising result was found by combining two impressive concentrations of each hormone. When MS basal media was supplemented with Kinetin 2.0mg/l + Benzyl Adenin A 0.5 mg/l, Kinetin 1.5 mg/l + Benzyl Adenine 0.5 mg/l and Kinetin 1.5 mg/l + Benzyl Adenine 1.0 mg/l respectively then 100% shoots were obtained. DOI: http://dx.doi.org/10.3329/ijarit.v1i1-2.13936 Int. J. Agril. Res. Innov. & Tech. 1 (1&2): 69-72, December, 2011