STUDIES ON THE ORIGIN OF SOME HYDROLYTIC ENZYMES ASSOCIATED WITH THE LEAVES AND TENTACLES OF DROSERA SPECIES AND THEIR ROLE IN HETEROTROPHIC NUTRITION

Abstract

SUMMARY Extracts from the leaves and tentacles of field‐grown plants of Drosera whittakeri, D. binata and D. auriculata had acid protease activity. Several pH optima were associated with some extracts, implying the presence of several proteolytic enzymes but other extracts showed proteinase activity at all acid pH values with no well‐defined pH optima. Only one distinct pH optimum of proteinase activity (pH 2.6) was associated with the leaves and tentacles of axenic cultures of D. binata. Chitinase activity was present in field‐grown plants of D. whittakeri and D. binata. It was not detected in axenic cultures of D. binata nor was it induced when chitin was applied to the tentacles of plants raised in axenic culture. Several of the many bacteria associated with field‐grown plants of D. whittakeri were isolated and found to secrete active extracellular proteinases with acid pH optima. These organisms could account for much of the proteolytic activity associated with extracts of field‐grown plants. Application of a fungicide/antibiotic mixture to the tentacles of non‐sterile plants of D. whittakeri inhibited insect‐enhanced growth. It is concluded that microbial hydrolytic enzymes play an essential role in this process.

THE SECRETORY CYCLE OF DIONAEA MUSCIPULA ELLIS IV. THE ENZYMOLOGY OF THE SECRETION

“…He found leucine aminopeptidase and several diand tripeptidase activities in the secretion of open pitchers, but was undecided as to whether these were native to Nepenthes or due to microbial contamination. Chandler and Anderson (1976) showed several pH optima from the leaves of three Australian species of Drosera, and Amagase (1972) found that leaf extract of Drosera peltata has a smooth pH-activity profile and one band of activity on a zymogram. The use of extracts is, however, of little value when considering the activity of the secretion of these plants.…”

Tentacles of in vitro-grown round-leaf sundew (Drosera rotundifoliaL.) show induction of chitinase activity upon mimicking the presence of prey

“…Carnivory of plants is thought to represent a special case of functional adaptation to the environment, allowing growth in nutrientpoor soils. The genus Droseraceae (sundews) consists of about 125 different species (Culham and Gornall 1994;Adamec 1997) that grow mostly on acidic soils or substrates that are often deficient in nitrogen and phosphorus (Chandler and Anderson 1976;Stewart and Nielsen 1992).…”

“…Chitinases are members of the pathogenesis-related proteins of plants and play a role in several vital plant processes (Kasprzewska 2003), such as plant defence against pathogens (Broglie and Broglie 1993;Melchers and Stuiver 2000). Chitinase activity was found in the mucilage from several carnivorous plants, for example, in Nepenthes mixta, N. maxima and Drosera peltata (Amagase et al 1972), species of the genus Utricularia (Sirova et al 2003), as well as in Drosera binata and D. whittakkeri (Chandler and Anderson 1976). Robins and Juniper (1980) demonstrated chitinase activity in the mucilage of Dionea muscipula.…”

Uptake and Metabolism of Insect Metabolites by Leaves and Tentacles of Drosera Species

“…Drosera binata and D. whittakeri were collected and maintained as described previously (Chandler and Anderson, 1976a). Axenic cultures of D. binata were raised as described by Chandler and Anderson (1976b).…”

“…Harder and Zemlin (1968) reported that Pinus pollen enhanced the growth of axenic cultures oiPinguicula lusitanica. Others have reported that micro-organisms play an important role in insect-enhanced growth of some carnivorous plants (Pringsheim and Pringsheim, 1962;Plummer and Kethley, 1964;Chandler and Anderson, 1976b). Chandler and Anderson (1976a) reported that insects serve as sources of sulphur and phosphorus for the nutrition, growth and development of Drosera whittakeri and D. binata.…”