N. Jayabalan

Rapid and High-Frequency In Vitro Plant Regeneration from Leaflet and Petiole Explants of Groundnut (Arachis hypogaea L.)

An efficient protocol for regeneration of groundnut plantlets from immature and mature leaflet and petiole explants excised from axenic seedlings has been developed. The highest frequency of callus induction obtained from leaflet explants was on Murashige and Skoog (MS) medium containing 2.0 mg/L of α-naphthalene acetic acid (NAA) and 0.5 mg/L of kinetin combination. MS medium containing different auxins in combination with 6-benzylaminopurine (BAP) induced shoot buds. A BAP (2.0 mg/L) and NAA (0.5mg/L) combination resulted in the highest frequency of shoot-bud regeneration. Subsequent shoot multiplication was obtained on MS medium supplemented with either BAP or kinetin (5.0 mg/L) in combination with NAA (1.0 mg/L). Immature leaflet explants were found to be more responsive to shoot induction than mature leaflet explants. Direct shoot-bud regeneration was also observed from petiole explants on the same regeneration medium used for leaflet callus. Regenerated shoots were rooted on MS medium containing indole-3-butyric acid (2.0 mg/L) and kinetin (0.5 mg/L). Plantlets obtained were successfully established in the field, where they grew to maturity and set viable seeds.

Radiation and chemical mutagen induced somaclonal variations through in vitro organogenesis of cotton (Gossypium hirsutum L.)

Abstract Purpose: The purpose of the investigation was to induce somaclonal variations by gamma rays (GR), ethylmethane sulphonate (EMS) and sodium azide (SA) during in vitro organogenesis of cotton. Materials and methods: The shoot tip explants were irradiated with 5–50 Gray (Gy) GR (Cobalt 60), 0.5–5.0 mM EMS and SA separately, and inoculated on Murashige and Skoog (MS) medium fortified with plant growth regulator (PGR) for organogenesis. The plantlets with well-developed root systems were acclimatized and transferred into the experimental field to screen the somaclonal variations during growth and development. Results: The number of somaclonal variations was observed in growth of irradiated/treated shoot tips, multiplication, plantlet regeneration and growth in vitro and ex vitro. The lower doses/concentrations of mutagenic treatments showed significant enhancement in selected agronomical characters and they showed decreased trends with increasing doses/concentrations of mutagenic agents. Conclusions: The results of the present study revealed the influence of lower doses/concentrations of mutagenic treatments on in vitro and ex vitro growth of cotton plantlets and their significant improvement in agronomical characters which needs further imperative stability analysis. The present observations showed the platform to use lower doses/concentrations of mutagenic agents to induce variability for enhanced agronomical characters, resistant and tolerant cotton varieties.