Transcriptome analysis of response to infection of cassava anthracnose disease (CAD) using an oligo-DNA microarray from cassava

Cassava Anthracnose Disease (CAD) that caused by the fungus Colletotorichum anthracnose is a serious disease of cassava in worldwide. In this study, we aim to establish the cassava oligo-DNA microarray representing approximately 30,000 cassava genes and apply it to investigate the molecular mechanisms against fungal infection using two cassava cultivars; Huay Bong 60 (HB60, resistant line for CAD) and Hanatee (HN, sensitive line for CAD). Based on expression profiling, we showed that the expression of various biotic stress-inducible genes, such as detoxification enzyme related genes is higher in HB60 under the treated conditions and non-treated condition, compared with HN. These results show that stress-inducible signaling pathways including ROS detoxification are constitutively activated in HB60 even under normal growth conditions without stress. These results suggest that our microarray is a useful tool for analyzing the cassava transcriptome and add new insight into the host responses of cassava against fungal infection. After cutting, the cassava plants were grown under natural light and temperature conditions in a greenhouse of Mahidol University in Thailand for about 8 weeks. The cassava plants were inoculated at the inter-nodal regions by stem puncture. Then total RNA was prepared from the leaves and used for the microarray hybridization. Three replicative hybridization experiments were carried out using the independent biological samples.