A Study on the Reaction of Some Grapevine Varieties to Crown Gall Agent (Agrobacterium vitis)

Grapevine is one of the oldest and most economically fruit crops. Grapes are a rich source of vitamins A, C, B6, as well as essential minerals, such as potassium, calcium, iron, phosphorus, magnesium and selenium. Crown gall disease (Agrobacterium vitis) is an economical disease in most vine yards. Since the bacterium remains in soil for a long time control of Agrobacterium is very difficult. Use of resistant rootstocks is the most effective methods for control of soil-borne pathogens, especially this bacterium. In this study, the reaction of the eight grape varieties (Shahani, Askari, Rish baba, Sefid-e-yaghuti, Qazvin Sefid-e-Keshmeshi, Qazvin Ghermez-e-Keshmeshi, Mehre and Rotabi) to crown gall was studied. In the first experiment, the rooted cuttings of different varieties inoculated in four sections with 20 ml of 108 cfu A. vitis and distillated water were compared as factorial experiment in a completely randomized design with four replications in green house. In the second set, inoculations were made by adding 40 ml of the suspension of two strains of bacteria (with the same concentration) around the root. Evaluations were made by growth and pathogenicity indices after five months. The callus formation on shoots was also studied in MS medium with and without bacterium. The results indicated that no varieties were immune to crown gall. Analysis of variance and mean comparisons of growth, physiological and pathogenicity indices showed the significant reduction in dry and wet weight of shoots and photosynthetic pigments in Shahni, sefid-e-yaquti and Rotabi. The soluble carbohydrate and anthocyanin also increased in these varieties. The highest necrosis, callus and gall formation were observed in Sefid-e-Yaghuti. It can be concluded that the Shahani, Rotabi and Sefid-e-Yaghuti varieties are most susceptible to causal agent of crown gall.