Comparative water loss from leaves of Solanum laciniatum plants cultured in vitro and in vivo

Water loss from fully turgid leaves of Solanum laciniatum Ait. plants cultured in vitro was considerably greater than that from either acclimatized plants or the parent plants from which cultures were established. Microscopic examination of lower epidermal strips from detached leaves (initially fully turgid) of transplanted and parent plants revealed 100% stomatal closure within 30 min. In contrast, half of the stomata from leaves of plants cultured in vitro were still fully open 16 h after detachment. Scanning electron microscopy revealed an absence of visible epicuticular waxes on leaves of plants cultured in vitro. However, since (1) leaf cuticles are mainly effective in controlling water loss after stomatal closure and (2) epicuticular waxes remained considerably reduced on leaves of acclimatized plants, the rapid water loss from leaves of S. laciniatum plants cultured in vitro was attributed primarily to failure of stomatal closure.