Authors: Shen Chen Zhanghui Huang Liexian Zeng Jianyuan Yang Qiongguang Liu Xiaoyuan Zhu
Publish Date: 2008/05/10
Volume: 22, Issue: 3, Pages: 433-441
Abstract
Bacterial blight BB caused by Xanthomonas oryzae pv oryzae Xoo is a devastating disease in rice worldwide The resistance gene Xa7 which provides dominant resistance against the pathogen with avirulence Avr gene AvrXa7 has proved to be durably resistant to BB A set of SSR markers were selected from the “gramene” database based on the Xa7 gene initial mapping region on chromosome 6 These markers were used to construct a highresolution genetic map of the chromosomal region surrounding the Xa7 gene An F2 mapping population with 721 highly susceptible individuals derived from a cross between the near isogenic lines NILs IRBB7 and IR24 were constructed to localize the Xa7 gene In a primary analysis with eleven polymorphic SSR markers Xa7 was located in approximately the 028cM region To walk closer to the target gene recombinant F2 individuals were tested using newly developed STMS sequence tagged microsatellite markers Finally the Xa7 gene was mapped to a 021cM interval between the markers GDSSR02 and RM20593 The Xa7linked markers were landed on the reference sequence of cv Nipponbare through bioinformatics analysis A contig map corresponding to the Xa7 gene was constructed The target gene was assumed to span an interval of approximately 1185kb which contained a total of fourteen genes released by the TIGR Genome Annotation Version 50 Candidategene analysis of Xa7 revealed that the fourteen genes encode novel domains that have no amino acid sequence similar to other cloned Xaxa genesThis research was supported by grants from the National High Technique Project 2006AA100101 the Guangdong Province Science and technique Project 0711124900076 the Guangdong Provincial Natural Science Foundation 2005B20101006 and the Fundamental Science Foundation of Guangdong Academy of Agricultural Science
Keywords: