Enzymatic activities in traps of four aquatic species of the carnivorous genus Utricularia

Abstract

Summary• Here, enzymatic activity of five hydrolases was measured fluorometrically in the fluid collected from traps of four aquatic Utricularia species and in the water in which the plants were cultured.• In empty traps, the highest activity was always exhibited by phosphatases (6.1-29.8 µmol l − 1 h − 1 ) and β -glucosidases (1.35 -2.95 µmol l − 1 h − 1 ), while the activities of α -glucosidases, β -hexosaminidases and aminopeptidases were usually lower by one or two orders of magnitude. Two days after addition of prey ( Chydorus sp.), all enzymatic activities in the traps noticeably decreased in Utricularia foliosa and U. australis but markedly increased in Utricularia vulgaris.• Phosphatase activity in the empty traps was 2-18 times higher than that in the culture water at the same pH of 4.7, but activities of the other trap enzymes were usually higher in the water. Correlative analyses did not show any clear relationship between these activities.• Trap comensals ( Euglena ) could be partly responsible for production of some trap enzymes. The traps can produce phosphatases independently of catching prey. Taking into account the enzymatic activities in traps, phosphorus uptake from prey might be more important than that of nitrogen for the plants.

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

“…The chitin cuticle of insect prey was suggested to be a source of nitrogen Gooday 1999), but more on a speculative than on an experimental basis. Previous analyses kept the possibility open that the chitinases observed were derived from microbial sources (Robins and Juniper 1980;Sirova et al 2003). Therefore, the analyses were performed with a representative from the sundew family that is successfully cultured aseptically in vitro, round-leaf sundew.…”

“…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.…”

“…Robins and Juniper (1980) demonstrated chitinase activity in the mucilage of Dionea muscipula. However, in none of these cases microbial contamination could be ruled out (Robins and Juniper 1980;Sirova et al 2003), so the action of plant-derived chitinases in the (possibly partial) decomposition of insect chitin is uncertain. This issue is part of a long-standing and ongoing debate on the role of insectivory and its relevance for plant nutrition, whether it is facultative or obligatory (Darwin 1878;Thum 1989;Stewart and Nielsen 1992).…”

Algae commensal community in Genlisea traps

“…On the other hand, it cannot be ruled out that algae in carnivorous plant traps compete with plant-host for nutrients from prey digestion (Adamec and Komárek 1999a;Jobson at al. 2000;Sirová et al 2003). Two dominant groups of algae, in the Genlisea trap environment, show ability to hydrolyze phosphomonoseters.…”

Enzyme production in the traps of aquatic Utricularia species

“…The above studies, however, did not determine extracellular enzyme activities directly in the trap fluid. Recently, Sirová et al (2003) investigated activities of five extracellular enzymes (aminopeptidase, phosphatase, β-hexosaminidase, α-and β-glucosidase) in the trap fluid from four aquatic Utricularia species. Phosphatase always exhibited the highest activity, while the activities of the other enzymes were usually lower by one or two orders of magnitude.…”