Effect of Cobra Venom on Pollen Germination and Pollen Tube Growth

Abstract

Snake venom contains biologically active constituents such as toxins and hydrolytic enzymes (Anima, 1968 ; Zeller, 1977). These are responsible for its lethal effect on animals. However, the same components if used in optimal quantities may lead to stimulation of some growth processes in plants. For example, heterocyst division in Anabaena doliolum is reported to be induced by application of cobra venom (Gupta and Dashora, 1973). In the present investigations, we have studied its effect on pollen germination and pollen tube growth in three dicots, ( Campsis grandiflora , Argentone mexicana and Crotalaria juncea ) and one monocot ( Crinum asiaticum). The optimal basal culture media for pollen of Crotalaria juncea , Campsis grandiflora , Argemone mexicana and Crinum asiaticum are 3 per cent sucrose +20 p. p.m. boric acid; 8-5 per cent sucrose + 50 p.p.m. boric acid; 6 percent sucrose + 10 p.p.m. boric acid and 10 per cent sucrose + 50 p.p.m. boric acid respectively. Various dilutions of the venom in water ranging from 1 to 20 p.p.m. were prepared in the respective basal media and its effect on pollen germination and pollen tube growth were studied at 26 + 2 °C. Three replicates were carried out for each experiment. Naja naja (cobra) venom was obtained from Biochemical Unit of Patel Chest Institute, New Delhi. The effect of various concentrations of cobra venom on pollen germination and pollen tube growth are shown in Table 1 and Plate 1. All the four species gave maximum response with 5 p.p.m. In Crinum asiaticum , Campsis grandiflora and Argenome mexicana both percentage germination and pollen tube growth were maximally stimulated by this concentration and higher concentrations had a smaller effect. However, in Crotalaria juncea the effect on pollen tube growth was lower than in the other species and there was no effect on germination. The increase in pollen germination caused by cobra venom may be due to the action of phospholipases which possibly loosen the pollen tube wall leading to enhanced tube growth. Alternatively, venom ATPase may act on pollen ATP as was suggested in the case of Anabaena doliolum heterocyst division. (Gupta and Dashora, 1975). Dormant pollen grains are known to contain large amounts of ATP (Nygaard, 1972, 1973) and its enhanced utilization may cause an increase in germination and tube growth. However, further studies are needed to distinguish between these hypotheses.