Resistance to Rhizoctonia solani and Presence of Antimicrobial Compounds in Camelina sativa Roots

Camelina sativa (L.) Crantz was significantly more resistant to Rhizoctonia solani Kühn than Brassica napus L. cv Westar. Emergence of C. sativa seedlings was 22 to 33% greater than those of Westar in R. solani-infested soil. The greater resistance of C. sativa seedlings to R. solani appeared to be due to greater amounts of antimicrobial compounds present in C. sativa roots. These antimicrobial compounds inhibited the growth of both weakly virulent and virulent R. solani isolates to the same extent. Four antimicrobial compounds were purified from C. sativa roots and their structures elucidated. Two were identified as the phytoalexins (camalexin and methoxycamalexin) previously described from C. sativa leaves. This appears to be the first report of elicitation of phytoalexins from roots of crucifers. Two preformed antimicrobial compounds were identified as methyl 1-methylindole-3-carboxylate and 10-methylsulfinyldecylisothiocyanate.