Plantlet Regeneration from Hypocotyl Callus of Solanum torvum Swartz

V. S. ]AISWAL and PRATAP NARAYAN

Department of Botany, Banaras Hindu University, Varanasi-221005, India

Received November 8,1983 . AcceptedJune 15, 1984

Summary Plantlets were produced from hypocotyl callus of Solanum torvum Swartz on Murashige and

Skoog's medium supplemented with various concentrations of growth regulators. Shoot buds differentiated when the basal medium was supplemented with 0.2 to 2.0 mg .1- 1 BAP and 0.1 to 1.0mg·I- 1 NAA. NAA alone at 0.1 to 1.0mg·I- 1 induced root formation. 2,4-D was inhib­itory for organogenesis.

Key words: Solanum torvum, Hypocotyl, Plantlet regeneration.

Introduction

The importance of the tissue culture technique has been widely recognised because of its extensive application in plant improvement (Murashige, 1974; Sharp and Lar­sen, 1979). In vitro regeneration of plants has been possible in a number of taxa (Fosket, 1980; Sen and Giles, 1983). However, success with shrubs and trees of me­dicinal importance have been infrequent. The present report describes successful regeneration of plandets from hypocotyl callus of Solanum torvum Swartz, a sola­naceous shrub of medicinal value.

Materials and Methods Seeds of Solanum torvum Swartz were germinated on moist filter paper in a petri dish under

aseptic conditions at 24 ± 1 °C in the dark. Segments of 3 mm were excised from the hypocotyl of seedlings and inoculated on MS medium (Murashige and Skoog, 1962) supplemented with growth regulators in various concentrations and combinations. The growth regulators used were IAA, NAA, 2,4-D, BAP and kinetin. Cultures were maintained at 25±2 °C with 12 h illu­mination at about 4000 Ix. For each treatment 50 cultures were raised and all experiments were repeated at least thrice.

Results

After one week of inoculation pale green to white callus grew from the cut ends of the hypocotyl segments. Callus proliferation took place on medium supplemented

Abbreviations: IAA = indole-3-acetic acid; NAA = naphthaleneacetic acid; 2,4-D = 2,4-di­chlorophenoxyacetic acid; BAP = 6-benzyl-aminopurine.

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382 v. S. ]AISWAL and PRATAP NARAYAN

Table 1: Morphogenetic responses of hypocotyl callus of Solanum torvum Swartz to various growth regulators. Each treatment consisted of 50 cultures and the results were scored after 45 days of culture.

MS+Growth regulators Morphogenetic response (%) Number of (mg· I-I) ±S.D. plantlets

BAP NAA 2,4-D Shootbuds Roots Plantlets per culture

0 0 0 0 0 0 0 0.2 0 0 20.0±1.0 0 0 0 1.0 0 0 24.0±1.0 0 0 0 2.0 0 0 22.0± 1.0 0 0 0 3.0 0 0 0 0 0 0 0 0.1 0 0 16.0±2.0 0 0 0 0.5 0 0 24.0±2.6 0 0 0 2.0 0 0 4.0± 1.0 0 0 0.2 0.1 0 10.0±2.0 0 4.0±1.7 1 2.0 0.5 0 20.0±2.6 0 10.0±1.0 2 2.0 1.0 0 0 0 16.0±2.6 2 0.2 0 0.4 0 0 0 0 0.5 0 1.0 0 0 0 0

with 0.1 to 2.0 mg . 1-1 IAA and was enhanced about two times by the addition of 0.5 to 2.0 mg· 1-1 kinetin. Better growth of callus was observed on medium supple­mented with 0.5 mg .1- 1 2,4-D in combination with 0.8 mg .1- 1 BAP. Four to five weeks old calli obtained from these cultures were subcultured on basal medium and on media supplemented with various growth regulators. No further growth took place in the callus when it was subcultured on basal medium but its growth continued in the presence of 0.2 to 2.0 mg .1- 1 BAP. After a fortnight, callus turned light green having some nodules. Shoot primordia developed from the light green portions of the callus, which subsequently differentiated into small shoot buds (Table 1). These shoot buds developed further to form fully differentiated shoots upto 2 cm within 7 weeks. Root formation took place in the medium supplemented with 0.1 to 2.0mg·l- 1 of NAA after 2 weeks of culture (Table 1). However, an increase in the concentration of NAA above 2.0 mg .1- 1 suppressed the root formation.

NAA (0.1 to 1.0 mg .1- 1) in combination with BAP (0.2 to 2.0 mg .1- 1) also in­

duced shoot bud formation. Media supplemented with 2.0 mg . 1-1 BAP and 2.0 mg .1- 1 NAA in combination or BAP alone above 2.0 mg .1- 1 totally inhibited bud formation. NAA (0.1 to 1.0 mg .1- 1

) in combination with BAP (0.2 to 2.0 mg ·1- 1) induced root formation in the cultures where shoot bud initiation was observed 3 weeks earlier, resulting into the formation of complete plantlets in some of these cultures (Table 1). At 2.0 mg .1- 1 of BAP and 1.0 mg .1- 1 of NAA plantlets attained a length of 5 cm at the end of 6 weeks of culture.

J. Plant Physiol. Vol. 119. pp. 381-383 (1985)

Plantlet regeneration with Solanum torvum callus 383

Discussion

Organogenesis in vitro cultures of Solanum torvum was obtained as a result of a balance among the growth regulators supplemented in the medium, as established in many species including some members of Solanaceae (Vasil et aI., 1979; Matsuoka and Hinata, 1979; Gupta and Chandra, 1982). In this species among the various cyto­kinins used, BAP exhibited the maximum shoot bud stimulation whereas of the var­ious auxins used, NAA was the most suitable for root formation.

Acknowledgements

We are thankful to Dr. (Mrs.) UmaJaiswal for reading the manuscript and to Mr. Madan Lal for technical assistance.

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J. Plant Physiol. Vol. 119. pp. 381-383 (1985)