The value of differential gene expression studies as tools to dissect the biological mechanisms is well established. There is a growing list of fungal and plant genes that are reported to be expressed specifically during pathogenesis. One of the main drawbacks to in planta gene expression profiling experiments is that RNA obtained from a plant during colonization by a fungus is derived mostly from the plant. Several research groups have attempted to overcome this using suppression subtractive hybridization (SSH).
SSH relies on two populations of RNA, the tester, which is usually derived from the tissue of interest, and the driver, which represents a complementary or comparative tissue. During the SSH process, the cDNA clones that are present in both the tester and driver are removed, preventing their occurrence in the final cDNA library. cDNAs that are present, then are expected to be strongly upregulated in the tester as compared to the driver.
Our understanding of anthracnose disease development is very limited. We are dissecting anthracnose infection sites and using the dissected cells, to construct cDNA libraries with the goal of performing transcriptional profiling using cDNA subtraction techniques to identify genes upregulated during early infection events.