Abstract:

In order to elucidate the molecular mechanism of the response of citrus to Citrus tristeza virus infection at late stage，a cDNA library was constructed by suppression subtractive hybridization with the RNAs from the leaves of citrus cultivar‘Shiranui’. Two hundred and ten positive clones were picked out randomly from library for sequencing. A total 192 valid ESTs were obtained. Clustering analysis indicated that 77 of them were non-repetitive sequences. Based on GO and KEGG analysis of these ESTs sequences from citrus genome database，the main functions of these ESTs were classified related to disease defense，stress，metabolism，transcription，transport and protein fate. Real-time RT-PCR analysis indicated that expression of 4 genes，including chitinase，jasmonate zim domain 1（JAZ1），calmodulin binding protein，caffeate O-methyltransferase were significantly up-regulated when citrus was infected by Citrus tristeza virus，indicating that these genes may be involved in the resistant response to Citrus tristeza disease. In this paper，we discuss the up-regulation of JAZ1 gene may indicate that the induction of systemic resistance in response to Citrus tristeza disease at late stage of virus infection is inhibited.

Key words: citrus, Citrus tristeza disease, suppression subtractive hybridization（SSH）, responsive gene