Division of Nematology, Indian Agricultural Research Institute New Delhi-12.
Presented at Nematology Symposium held at Coimbatore, India in February, 1981
Investigations aimed at exploring the basic molecular mechanism in the plant-nematode interaction in relation to the resistance of tomato plants to Meloidogyne incognita were carried out. The total RNA content increased in roots of both the varieties, the increase being remarkable in the resistant var. SL-120. A general increase in RNA nucleotides was noticed in the inoculated plants; the increase was in the adenylic and guanylic acids in Pusa Ruby (susceptible var.) while in SL-120 cytidylic and guanylic acids had increased. In parallel, the soluble proteins were also observed to increase. A bimodal increase in RNase activity in galled tissues, one early and the other quite late during infection was noticed. Contrary to this, only a unimodal increase was seen in the resistant reacting variety. The possible contribution of the nematode as contaminants to the increase in plant RNase was judged to be insignificant. Purification and characterization of the RNase activity from the inoculated and healthy plants of both the varieties gave clear indications for do novo synthesis of RNase isozyme in the inoculated SL-120. The results are hence suggestive of preferential synthesis of RNA in the inoculation tomato, especially in the resistant reacting plants. Indications are there to suggest an acceleration of the protein biosynthetic machinery of the cell quite early during infection. On the basis of the studies conducted,in this laboratory and elsewhere, a hypothesis on the molecular events taking place in plant-nematode interaction has been suggested.
