Influence of sugars and light on rhizosecretion of α-glucosidase and acid phosphatase during micropropagation of potato

Abstract

The effects of carbohydrate supply and light on rhizosecretion during micropropagation of potato plantlets (Solanum tuberosum L., cv. ‘Iwa’) in liquid medium were investigated. Soluble protein content was higher in the spent medium for plantlets grown under light conditions than in the dark. For those plantlets grown under light conditions and on different sugar-supplemented media, they rhizosecreted the highest amount of soluble protein when grown in the presence of maltose, while they rhizosecreted the lowest amount of soluble protein when grown on medium containing glucose. Moreover, plantlets grown under light and on a medium containing sucrose were the most vigorous, and exhibited the highest levels of rhizosecreted acid phosphatase activity. However, there was no direct relationship between plantlet growth and rhizosecretion. When plantlets were grown in the dark and on medium containing maltose, a higher α-glucosidase activity was detected than those grown on medium containing sucrose. These results suggested that rhizosecretion of certain proteins from plantlets grown in vitro might not require exposure to light conditions.