In vitro culture responses, callus growth and organogenetic potential of brinjal (Solanum melongena L.) to He-Ne laser irradiation

The present investigation was designed to analyze the influence of Helium-Neon (He-Ne 632.8 nm) laser irradiation on defense enzymes, proline content and in vitro responses of callus induction, shoot initiation and on plantlet regeneration potential of brinjal. The seeds of Mattu Gulla (Solanum melongena L.) were irradiated with 20, 25 and 30 J/cm² of He-Ne laser followed by surface sterilization and sprouted on Murashige and Skoog medium without plant growth regulators. The activity of defense enzymes, proline content and the organogenetic potential of hypocotyl, leaf and shoot tip explants were determined from thirty day old seedlings. During seed germination, most of the seedlings showed normal two cotyledons whereas small number of seedlings showed tricotyledonous at 20 J/cm² treatment and no other morphological abnormalities were observed during further growth and development. There was no substantial variation was noted in both β-1,3-glucanase and chitinase activity as well as proline content which proves the He-Ne laser irradiation does not causes any stresses for the plant. The in vitro culture of hypocotyl, leaf and shoot tip explants from laser irradiated seedlings showed differential responses as compared to un-irradiated control. The laser induced enhancement of callus induction, growth rate of callus tissues and shoot tip, percentage of responses of shoot and root initiation, days to shoot and root initiation, shoots formed per callus, number of roots per shoots, length of roots and nuclear DNA content of in vitro raised plants were evaluated. Among the tested laser doses (20, 25 and 30 J/cm²), 25 J/cm² showed significant biostimulatory effect over un-irradiated control seedlings. The present observations reveal and endorsed our earlier reports with substantial enhancement of in vitro and ex vitro by He-Ne laser irradiation.