Defense and carnivory: Dual role of bracts inPassiflora foetida
- 113 Downloads
Members of the genusPassiflora are reported to have evolved modifications which kill insects; they have however never been tested for carnivorous syndrome. The flowers ofPassiflora foetida consists of highly reticulate bracts which cover and grow along with the buds and fruits. Removal of bracts from developing bud and fruit resulted in higher predatory damage compared to those where the bracts were intact. These bracts also possess a large number of minute glands which ooze sticky secretion. A variety of tiny insects were found trapped by the secretion of the bracts. The secretion of these glands show high proteases and acid phosphatase activity, two common digestive enzymes found in traps of true carnivorous plants. A high quantity of aminoacids were released from freshly freeze killed ants when incubated in buffer extract of bracts-[14C] phenylalanine smeared on the glandular surface of bracts was recovered from ovules suggesting potential for absorption of aminoacids. These results suggest a novel role for bracts where primary function is to minimize predatory damage to developing flowers and fruits. The bracts serve as insect traps and also possess the mechanism to digest the trapped insects to obtain free aminoacids.
KeywordsPassiflora foetida bracts proteolytic enzymes carnivory
Unable to display preview. Download preview PDF.
- Amagasse 1972 Digestive enzymes in insectivorous plants III. Acid proteases in the genusNepenthes andDrosera peltata;J. Biochem. Tokyo 72 73–81Google Scholar
- Benzing D H 1987 The origin and rarity of botanical carnivory;TREE 2 367–369Google Scholar
- Dutta A C 1988A text book of botany (Calcutta: Oxford University Press)Google Scholar
- Heslop-Harrison Y 1975 Enzyme release in carnivorous plants; inLysozomes in biology and pathology (eds) J T Dingle and R T Dean (Amsterdam: North Holland) vol 4, pp 525–578Google Scholar
- Heslop-Harrison Y 1976 Enzyme secretion and digestive uptake in carnivorous plants; inPerspectives in experimental biology S E B Symposial Volume 2.Proceedings of the 50th Anniversary Meeting, Cambridge, 1974 (ed.) N Sutherland (Oxford: Pergamon Press) pp 463–476Google Scholar
- Juniper B E, Robins R J and Joel D M 1989The carnivorous plants (New York: Academic Press)Google Scholar
- Kakade M L, Simons N R and Liener I S 1969 An evaluation of natural versus synthetic substrates for the autotryptic activity of soybean samples;Cereal Chem. 46 518–521Google Scholar
- Lloyd F E 1942The carnivorous plants (Waltham: Chronica Botanica Co.)Google Scholar
- Rachmilevitz T and Joel D M 1976 Ultra structure of the calyx glands ofPlumbago capensis Thumb. in relation to the process of secretion;lsr. J. Bot. 25 159–168Google Scholar
- Sutherst R W and Wilson L J 1986 Tropical legumes and their ability to immobilize and kill cattle ticks; inInsects and the plant surface (eds) B E Juniper and T R E Southwood (London: Edward Arnold)Google Scholar