شناسایی باکتری Bacillus subtilis subsp spizizenii با پتانسیل شدید ایجاد بیماری لکه برگی در درختان کیوی

Since Iran is one of the major producers of kiwifruit in the world, it is very important to pay attention to maintaining the health of this plant. Therefore, identifying pests and diseases threatening of this plant has special importance in the country. On the other hand, the epidemic of bacterial pathogens is a serious threat to kiwifruit. In wide sampling of kiwifruit orchards in Iran, for two successive years and three different agronomic stages, symptoms of leaf spot on kiwifruits leaves observed and numerous samples from these diseased plants selected. In laboratory tests, from kiwifruits leaves with symptoms, variety of bacterial strains isolated. After the pathogenesis test on kiwifruit leaf, water-soaked symptoms with production red liquid observed that it was identical with the orchards symptoms. Among pathogenic isolates, three isolates with white colonies and jagged margins had a very high pathogenicity on the leaves of kiwifruit seedlings in the greenhouse. The results of complementary phenotypic tests and 16s rDNA gene sequencing showed that these isolates belonged to Bacillus subtilis subsp spizizenii with 99.68% similarity. This is the first report of pathogenic potential in this subspecies. Therefore, more detailed studies, including sequencing of the entire genome, are necessary to identify virulence genes and their virulence mechanisms.