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Title: EXPESSION OF DEFENSE GENES IN ROOT TISSUES OF TWO SOYBEAN CULTIVARS WITH DIFFERENT LEVELS OF PARTIAL RESISTANCE TO PHYTOPHTHORA SOJAE

Author
item COSTANZO, S - OSU
item Redinbaugh, Margaret
item DORRANCE, A - OSU

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2004
Publication Date: 8/30/2004
Citation: Costanzo, S., Redinbaugh, M.G., Dorrance, A.E. 2004. Expession of defense genes in root tissues of two soybean cultivars with different levels of partial resistance to phytophthora sojae. Phytopathology. 94:S21.

Interpretive Summary:

Technical Abstract: Phytophthora sojae is the causal agent of root and stem rot of soybean, and is considered a major constraint to the production of this crop worldwide. In partially resistant soybeans, the damage caused by the pathogen is restricted to the tap root and lower stem. An earlier study suggested that the interface between the expanding lesion and healthy tissue is the site where active lesion-limiting mechanisms and defense responses are important. To confirm this initial finding, we used Northern blot analysis to determine the expression level of nine defense-related genes including pathogenesis-related (PR) proteins and enzymes of the phenylpropanoid pathway during the course of infection. After artificial inoculation of soybean cultivars Conrad (partially resistant) and OX20-8 (susceptible) with P. sojae isolate 34.S.5.1, 1.5 cm long root sections were collected at 0, 6, 12, 24, 48, 72 and 120 h after inoculation (h.a.i.). Analogous root tissue samples were collected from non-inoculated and mock inoculated control plants. No difference in the expression of basic peroxidase and 4-coumarate Co-A ligases 1 and 2 was noted between the two cultivars, but levels of beta-1,3-endoglucanase (EGL) and matrix metalloproteinase (MMP) were significantly greater in Conrad at 72 h.a.i. These results suggest a possible involvement of EGL and MMP as factors involved in the expression of partial resistance to P. sojae in soybean.