Abstract: In the present study, according to the results of Citrus sinensis SSH library analysis, primers of one up-regulation expressed EST sequence were designed, a MYB type gene was cloned by rapid amplification of cDNA ends (RACE). This gene was named as CsMYB, and submitted in GenBank (accession No. HQ841074). The full-length cDNA sequence of CsMYB is 1 306 bp, including an open reading frame (ORF) of 909 bp and the typical 26 bp poly-A. Bioinformatics analysis showed that the gene putatively encodes a protein which has 302 amino acids with molecular weight 32.97 kD, and its theoretical pI is 8.5. The CsMYB gene contains two typical conserved motifs: R2 and R3. The gene expression profile under the treatment of Ca. Liberibacter asiaticus(Las) was investigated by Real-time qPCR. The results showed that CsMYB gene expression varied at different times infected by Las, and was different in huanglongbing development progresses. Therefore, the CsMYB gene is speculated to be a transcription factor and possibly to be involved in the procedure induced defense of Las.

Key words: Citrus sinensis, huanglongbing(HLB), MYB, RACE, Real-time quantitative PCR