MICROARRAY COMPARISON OF TALL FESCUE GENE EXPRESSION IN ENDOPHYTE INFECTED AND ENDOPHYTE FREE PLANTS

Authors: Dinkins, Randy

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/8/2006
Publication Date: 11/12/2006
Citation: Dinkins, R.D. 2006. Microarray comparison of tall fescue gene expression in endophyte infected and endophyte free plants. ASA-CSSA-SSSA Annual Meeting Abstracts. Nov 12-16, 2006.

Interpretive Summary:

Technical Abstract: Many grasses have mutualistic symbioses with fungi of the family Clavicipitaceae. Tall fescue (Lolium arundinaceum) can harbor the obligate endophyte, Neotyphodium coenophialum that are asexually propagated and transmitted via host seeds. The endophyte receives shelter and nutrients from the host plant and in turn produces anti-herbivory compounds targeted towards insects and mammals. In addition, plants with the endophyte are more stress resistant, although the mechanism for this resistance is unknown. In an effort to begin to dissect the host plant endophyte cross-talk, global gene expression was analyzed using the Affymetrix Wheat Genome Array GeneChip®. Total RNA was isolated from pseudostems of known endophyte-infected and endophyte-free plants and tested in triplicate. Overall only 14-15% of the probe sets were called present on each chip somewhat lower than expected due to the relatedness between fescue and wheat. However, 219 probe sets were observed to be differentially expressed greater than two-fold (P<0.01) between the endophyte infected and endophyte free plants. PCR primers were designed to a number of fescue EST’s with homology to EST’s on the Array GeneChip® and tested to verify the expression profile observed on the microarray experiments. Initial results using forty primer pairs have shown that some primers gave results similar to the expected based on the microarray experiments, including a number of wheat probe sets that contain fungal sequences. In some cases no differences were observed between the endophyte infected and endophyte free, and it is unknown whether this is indicative of the particular gene or allele that was used compared to what was detected on the array. Some of the primers did not produce a PCR product, and additional primers will be synthesized to determine whether the primers did not function or whether the RNA is not present in these tissues. Experiments are ongoing and results will be presented.