REGENERATION OF PEPPERMINT AND ORANGE MINT FROM LEAF-DISKS

Leaf disks from peppermint, spearmint, orange mint, lavender mint and Scotch spearmint were cultured on various Murashige-Skoog-based media in order to regenerate shoots. A significantly larger average number of orange mint leaf disks regenerated shoots on basal medium containing 44.4-mu-M benzyladenine (BA) and 250 ml l-1 coconut water (CW). Shoots regenerated from peppermint leaf disks cultured on basal medium containing 44.4-mu-M BA and 250 ml or 450 ml l-1 CW. The most shoots regenerated from orange mint leaf disks cultured on medium containing 10 g l-1 washed Difco Bacto-agar. Disks excised from the bases of the first expanding pair of orange mint leaves cultured under dark conditions regenerated a significantly larger average number of shoots. Histological studies suggested that shoots regenerated from the palisade parenchyma cells associated with vascular tissue.