the plant tumors

this study is a survey type of work on the plant tumors and their characteristics in genera1; special attention is given to those tumors which are caused by grobacterium tumefactions and also by plant hormones. the type of work and the methods are very much similar to the work of other investigators, but attempt was made to compare the results which are obtained upon the local varieties of a large group of plant species grown in iran with those which were obtained in other parts of the world, the results obtained clearly demonstrates that the tumorogenic effect of agrobacterium mefaciences is not universal among all plant species, as there are some plants which are quite resistant and will not produce any tumor upon the inocu1ation of the acteria. for example tradescantia spp. did not produce any tumors neither they showed any sign of infection. on the other hand the degree of the responses toward the umorogenic effects of the bacteria was shown to be quite different among the plants which were susceptible. sunflower (h elianthues annus) tomato (lycopersicum esculantum) and tobacco (nicotiana tubacum) were most sensitive toward the bacteria and produced the largest size of the tumors, whereas plants such as the common peas (pisum sativrum) and the common beans (phasealus vulgaris) the tumors produced were very small and did not have much inhibitory effect on the growth of the infected plants as compared with, the controls. unsuccessful attempt was made to induce tumors upon the leaf of different plants, this observation infect contradicts the results obtained by other workers and the viability of the bacteria in the tumors was also being investigated. some results with the hormones and also discussed in this paper, and finally histological, studies on the tumors tissue are also reported here.