Detection of phytopathogenic bacteria on bean seed and cultivar susceptibility. [Doctoral dissertation] | Detekcija fitopatogenih bakterija na semenu pasulja o osetljivost sorti. Doktorska disertacija

The present dissertation discusses the occurrence and severity of bacterial bean diseases in the Serbian Province of Vojvodina. Leaf samples of diseases bean plants were collected from a number of locations in the province. All the samples from all the locations tested positive for Xanthomonas axonopodis pv. phaseoli, indicating that the bacterium is widespread on commercial plots and gardens planted to bean in Vojvodina. The bacterium Pseudomonas savastanoi pv. phaseolicola was isolated from a smaller number of samples, which shows that it is not widespread on bean in the province. Identification of the isolates was confirmed using the classic phytobacterial methods as well as the rapid modern methods. As the seed is the primary source of inoculum, the present study used methods recommended by the ISF to detect and identify the bacteria X. a. pv. phaseoli and P. s. pv. phaseolicola on seeds of bean and string bean. The methods involved extraction of bacteria from the seeds and their isolation onto semi-selective medium for the purpose of testing the pathogenicity of the isolates obtained. We tested bean and string bean seeds from commercial crops (23 cultivars) that had been naturally infected as well as some imported string bean seeds. The identification of the X. a. pv. phaseoli and P.s. pv. phaseolicola isolates obtained from the bean and string bean seeds was confirmed using the rapid modern methods (ELISA and PCR). The most reliable way for detection and identification of phytopathogenic bacteria on seeds can be obtained with combination of classic and rapid modern methods. Our two-year study (2005-2006) of susceptibility to X. a. pv. phaseoli of 26 domestic and foreign cultivars of Phaseolus vulgaris under natural and artificial infection conditions has shown that none of the cultivars are immune to the pathogen. Our one-year study of susceptibility to P. s. pv. phaseolicola of 24 domestic and foreign cultivars of P. vulgaris under natural infection conditions has shown the most of the cultivars are slightly susceptible to this bacterium.