Abstract:

【Objective】 This study aims to construct a BAC library of ‘Guanximiyou’, and screen the library based on EST sequence related to granulation. 【Method】 High molecular weight DNA was obtained by gentle physical homogenization. The DNA was partial digested by restriction endonucleases, and cloned to BAC vector. The positive clones were conserved. BAC clones were pooled for PCR screening. The sequence of positive clone was analyzed. 【Result】 Method of BAC library construction was improved. The library consists of 26 112 clones. A random sample of 100 clones indicated an average insert size of 120 kb, corresponding to 8 genome equivalents. Less than 1% of the clones did not contain inserts. Screening of BAC library with chloroplast DNA probes indicated that less than 1% of the clones contained organelle-derived DNA. The BAC library was screened with a pair of primer deprived from EST related to granulation. A 1 088 bp DNA sequence was amplified by PCR. It contained two introns with the length 122 bp and 172 bp, respectively. The sequence has 85% and 71% identities with multicopper oxidase cDNA sequences of Ricinus communis and Populus trichocarpa, furthermore, it has 76% and 73% identities with pectinesterase cDNA sequence of Annona cherimola and Arabidopsis thaliana, respectively. 【Conclusion】 According to the characterization of BAC clones and the results of screening, the library is suitable for functional genome research on ‘Guanximiyou’. Two genes related to granulation were predicted.

Key words: Guanximiyou, BAC library, granulation, library screening