Genomic Comparative Analysis Combined with Linkage Map to Illustrate the Molecular Mechanism of Precocious Flowering in Citrus Plan

The transition to flowering is one of the most important developmental processes in plants. Citrus plants usually have a 6-11 years long juvenile period, which greatly obstacles the breeding efficiency and understanding of the molecular basis of economically important traits. Recently, a natural mutant of trifoliate orange with short juvenility (1-2y) was found in Hubei, China. To understand the long juvenility in citrus plants, a genomic comparative analysis between the precocious trifoliate orange and wild type was made based on the result of genome re-sequencing referenced with the genome data of Citrus sinensis (http://citrus.hzau.edu.cn/orange/index.php) and C. clementina. The re-sequenced genome of the precocious trifoliate orange and wild type covered 61.46% and 62.78％, respectively rate to the reference genome. Total of 2956644 and 3133860 SNPs were obatained respectively from the mutant and wild type, in which they shared 2433443 SNPs compared with genome of C. clementina. Total of 24716 and 26940 structural variation (SV) were found respectively in the mutant and wild type, shared 3705 SV, as compared with reference genome. Total of 223 SSR markers were used to construct a linkage mape based on a F1 hybrid segregant population crossed between C. clementina and precocious mutant of Poncirus trifoliata. Further analysis is expected to localize the hypothesized gene controlling the juvenile development in citurs plant based on the linkage map and comparisom on genome sequences between prococious mutant and the wild type.