Xanthomonas euvesicatoria (Xev) causing bacterial spot of pepper is a seed-borne bacterium. This study was carried out to find the best way to remove the X. euvesicatoria in pepper seeds. Seeds were inoculated with Xev suspension(108cell/ml) for 10min using vacuum pump(580mmHg). Seeds were treated in hot water 52, 54, 56℃, 3% H2O2, 1% NaOCl for 30min and in Benoram, a commercial seed disinfectant, for 1h. In case of hot water treatment, seeds were pre-warmed in 37-40℃ for 10min, then were transferred to each temperature treatment (52, 54, 56℃) and treated for 30min. At the completion of heat treatment, seeds were put in cool water. The seeds were dried in laminar flow hood. After drying 400 seeds from each treatment were put on Tween Medium B(TMB, McGuire, 1986) and were incubated at 28℃. Xev recovery was recorded after 72h. No bacterial colony was found in 54℃, 56℃ and 3% H2O2 treated seeds. Germination percentage was over 98% for all treatments except hot water treatment at 56℃. Germination was reduced to 92% by hot water treatment at 56℃. For the test of plating seed washings, treated seeds put 3ml/g of sterile 10mM phosphate buffered saline (PBS) in 250ml flasks and the seed samples were shaken for 2 h at room temperature and at 115 rpm. After 2h, the seed washings were filtered through 2 layers of gauze. The washings were centrifuged at 12,000g for 20min at 10℃. Supernatant was discarded and the pellets were resuspended in 1ml of PBS. The concentrated washings were plated in a series of 10-fold serial dilutions from 100 to 10-6. An aliquot of 0.1ml of diluted solution was plated on TMB in 3 replications. The number of colony developing was counted after 96h. No colony of the bacterial pathogen was found in the treatments of hot water 56℃ and 3% H2O2. Whereas, 6.0x101CFU/ml, 8.7x104CFU/ml, 4.8x105CFU/ml, and 1.2x107CFU/ml was recovered at hot water 52℃, 1% NaOCl, benoram, and control, respectively.
Another study was conducted for preparing class material for genetics and plant breeding laboratory. PI370001 produces purple immature fruit, flower, leaf and stem, whereas Chilbok No. 2 produces green immature fruit and leaf. Chilbok No. 2 has Bs2 gene that is a gene conferring hypersensitive resistance to bacterial spot (Xanthomonas euvesicatoria). PI370001 and Chilbok No. 2 were crossed and F1, F2, BC1P1 and BC1P2 populations were developed. Segregation for fruit position, hypersensitive resistance to bacterial spot, and purple color on foliage and immature fruits were investigated. In leaf color, F1 plants were green leaved and the F2 generation segregated into 3 green : 1 purple ratio. In immature fruit color, F1 plants were purple and the F2 generation segregated into 1 green : 3 purple. Fruit position and Bs2 gene were controlled by single dominant gene. Among the L*, a* b* value of immature fruit and leaf, b* value was shown associated with purple color. Inheritance of the purple was quantitatively analysed with b* value. The results suggested that purple color of leaf was controlled by a recessive gene and modifiers but purple color of immature fruit was inherited in a mode of a dominant gene with modifier genes.