Microarray expression analysis of Nagami kumquat in response to canker infection

Citrus canker disease, caused by a bacterial pathogen Xanthomonas axonopodis pv citri, affects a variety of citrus species and citrus relatives in many areas of the world. Kumquats have shown an apparent resistance to canker that was not unraveled. In this study, incompatible interaction of Fortunella margarita and Xanthomonas axonopodis was confirmed using bacterial growth curves.; Forward and reverse subtractive cDNA libraries were constructed using Nagami kumquat mRNA to identify genes that are differentially expressed during the infection. A number of cDNA clones were selected for sequencing. Homologues to transcription factors, receptor and resistance genes known to be involved plant-pathogen interaction were identified. The expression profiles of 2304 of these genes were analyzed using cDNA microarrays. The results demonstrate how the use of microarray expression profiling can help elucidate plant pathogenesis-related response mechanisms and assign roles for previously uncharacterized genes. This can be considered to be a case study in citrus that has used these high throughput technologies to understand the defense mechanisms in Fortunella and citrus at the molecular level.