Screening Of Molecular Markers Of Resistance To Tobacco Brown Spot

Tobacco is one of the major cash crops in China. Tobacco brown spot disease caused by Altemaria alternata has been a serious leaf disease in tobacco production. It will break out and cause huge damage to the tobacco production when the climate is suitable for its occurrence. The best measure to control the disease is planting the resistant cultivars. We can develope new resistant varieties by molecular marker-assisted selection efficiently. The study is mainly aiming to three parts: (1) Testing the hereditary pattern of the brown spot resistant genes from Beinhart 1000-1 and Jing-yehuang; (2) Developing an efficient PCR reaction system for SRAP detecting; (3) Establishing F₂ population and using bulked segregant analysis to screen SRAP markers linked to the brown spot resistant genes. The main results are as follows.(1) The resistant gene from Beinhart 1000-1 is controlled by a single dominant gene while the resistance of Jing-yehuang is not controlled by single gene.(2) An efficient PCR reaction system for SRAP detecting was established. The system has been proved reliable, repetitive and productive.(3) SRAP combined with bulk segregant analysis was used to identify SRAP markers linked to the resistant genes. 800 pairs of SRAP primers were screened. The SRAP analysis to the F2 population showed that the marker S1118₃₆₀ is linked to the brown spot resistant gene from Beinhart 1000-1, and the marker S2113₃₄₀ is linked to the brown spot resistant gene from Jing-yehuang.