|Samac, Deborah - Debby|
Submitted to: North American Alfalfa Improvement Conference
Publication Type: Abstract Only
Publication Acceptance Date: 7/29/2002
Publication Date: 7/29/2002
Citation: SAMAC, D.A., PENUELA, S., DANESH, D., YOUNG, N.D., VANDENBOSCH, K. PATHOSYSTEM DEVELOPMENT AND TRANSCRIPTOME ANALYSIS OF PATHOGEN INTERACTIONS WITH MEDICAGO TRUNCATULA. NORTH AMERICAN ALFALFA IMPROVEMENT CONFERENCE. 2002. ABSTRACT. P. 48. Interpretive Summary:
Technical Abstract: Medicago truncatula is being developed as a model plant for functional genomics studies of plant-microbe interactions. A set of 30,000 non-redundant genes is being established for microarray-based gene expression studies. At present, glass slide microarrays containing 1152 cDNAs including positive and negative controls are being used for hybridization with labeled targets derived from pathogen infected and uninoculated leaf and root tissues. To fully utilize microarray analysis of plant-pathogen interactions, a spectrum of host responses, from fully resistant (incompatible) to fully susceptible (compatible), need to be identified. Plants from a collection of 119 accessions of M. truncatula, including 10 cultivars, were screened for reaction to Phytophthora medicaginis (Phytophthora root rot), Phoma medicaginis var. medicaginis (spring black stem and leaf spot), and Colletotrichum trifolii (anthracnose). In seedling assays, 92% of the entries were scored as susceptible to Phytophthora root rot with brown necrotic lesions on hypocotyls and upper roots. Susceptible plants were stunted but not killed. In a detached leaf assay, 94% of the entries were scored as susceptible to Phoma in which more than 25% of the leaf was yellowed. Reactions of seedlings to Colletotrichum trifolii race 1 and 2 were similar, showing moderate to complete cotyledon yellowing. Infections only occasionally spread to stems and leaves were not infected. An alfalfa isolate of powdery mildew identified as Erysiphe pisi was used to inoculate 20 accessions of M. truncatula in the greenhouse. Two entries were resistant, three showed a hypersensitive response, two were partially resistant, and the rest were susceptible.