|TAKAHASHI, YURI - University Of California|
|WALKER, ANDREW - University Of California|
Submitted to: Biomed Central (BMC) Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/7/2010
Publication Date: 7/1/2010
Citation: Cheng, D.W., Lin, H., Takahashi, Y., Walker, A.M., Civerolo, E.L., Stenger, D.C. 2010. Transcriptional Regulation of the Grape Cytochrome P450 Monooxygenase Gene CYP736B Expression in Response to Xylella fastidiosa Infection. Biomed Central (BMC) Plant Biology. 10:135.
Interpretive Summary: Plant cytochrome P450 monooxygenases belong to a gene family involving varieties of functions including biosynthesis of an array of the secondary compounds which act as plant defense agents. To determine if cytochrome P450 monooxygenase CYP736B gene is involved in defense response to Xylella fastidiosa infection, the patterns of gene expression were investigated in leaf and stem tissues of Pierces disease (PD) resistant and susceptible grape plants after inoculation with the pathogen. Expression of CYP736B gene in leaves of PD resistant plants increased in response to Xf infection while gene expression decreased in leaves of PD susceptible plants 6 weeks after X. fastidiosa infection. However, CYP736B expression was very low in stem tissues at all evaluated times in both PD resistant and susceptible plants. CYP736B expression appeared to be regulated by three candidate transcription start sites (TSS) located upstream and three candidate polyadenylation (PolyA) sites downstream of the gene. Results indicated that these multiple transcription start and polyadenylation sites as well as their interactions may contribute to regulation of grape CYP736B gene expression. This study provides basic information regarding regulation of a host defense gene that may facilitate development of improved resistance in grape to Pierce’s disease.
Technical Abstract: Plant cytochrome P450 monooxygenases are a group of versatile redox proteins that mediate the biosynthesis of lignins, terpenes, alkaloids, and a variety of other secondary compounds which act as plant defense agents. To determine if cytochrome P450 monooxygenases are involved in defense response to Xylella fastidiosa infection, the transcriptional and posttranscriptional modification patterns of cytochrome P450 monooxygenase gene CYP736B were investigated in leaf and stem tissues of resistant and susceptible grape plants after inoculation with this pathogenic bacteria. CYP736B transcript was up-regulated in resistant plants and down-regulated in susceptible plants at 6 weeks after X. fastidiosa inoculation. However, CYP736B expression was very low in stem tissues at all evaluated times. 5’RACE and 3’RACE sequence analyses revealed that there were three candidate transcription start sites (TSS) in the upstream region and three candidate polyadenylation (PolyA) sites in the downstream region of the grape CYP736B gene. The usage frequencies of each transcription initiation site and each polyadenylation site varied depending on plant genotype, developmental stage, tissue, and treatment. Statistical analysis revealed that coordination of different 5’ transcription initiation sites and different 3’ polyadenylation sites contributed to the final determination of CYP736B pre-mRNA splicing efficiency in both PD resistant and susceptible grapevines. These results demonstrate that expression of the grape CYP736B gene is regulated developmentally and in response to Xf infection at both transcriptional and post-transcriptional levels. Multiple transcription start and polyadenylation sites as well as their interactions may contribute to regulation of grape CYP736B gene expression.