A lower, but significant response was also ob served for INDOLE GLUCOSINOLATE O METHYL currently TRANSFERAE1, a marker gene for O. A com parative analysis of the mRNA data shown in Figure 6C demonstrates that some genes are already upregulated in unchallenged cycam1 seedlings relative to the WT control and this effect is further promoted by the pathogen, while in other cases it is primary the pathogen infection that stimulates the accumulation of the mRNAs in the mutant seedlings. Apparently, Inhibitors,Modulators,Libraries the ROS related genes respond dif ferently to changes in the ROS levels, which might be due to the different regulation in response to the different ROS. Furthermore, the higher ROS levels after A. brassi cae infection may be partially caused by less efficient ROS scavenging, since the mRNA levels for several ROS scav enging enzymes which are upregulated in WT roots after A.

brassicae infection, are not upregulated in the roots of the cycam1 mutant. Phytohormone Inhibitors,Modulators,Libraries levels are altered in cycam1 The phytohormones salicyclic acid, jasmonic acid and ABA play crucial roles in regulating growth and devel opment and coordinate the plants responses to biotic and abiotic stresses. SA, JA and ABA dependent stress responses are regulated by cyt levels in plants. To check whether the SA, JA and ABA levels are altered in the mutant, their levels were first measured in 14 d old cycam1 1, cycam1 2 and WT seedlings grown on MS medium. The SA and ABA levels were slightly, but sig nificantly higher in cycam1 1 and cycam1 2 seedlings not exposed to stress compared to the WT control.

Inhibitors,Modulators,Libraries The JA level and that of its precursor cis 12 oxo phytodie noic acid were not affected by the mutation. However, the inactive form jasmonoyl isoleucine conjugate, JA Ile, and the bio active form 7 iso JA Ile Inhibitors,Modulators,Libraries were higher in cycam1 1 and cycam1 2 compared to the WT. This sug gests that JA modifying enzymes, but not JA synthesis, are targets of the cycam1 mutation. In conclusion, the levels of SA, ABA and the bioactive 7 iso JA Ile are higher in the Ca2 mutants, even when they are not exposed Inhibitors,Modulators,Libraries to stress. A. brassicae infection induced SA, ABA and JA accu mulation in WT and cycam1 seedlings. Induc tion of the phytohormone levels is quite similar in WT and the cycam1 mutant, when the % stimulation by the pathogen is considered, except that the biologically active form of JA, 7 iso JA Ile, p53/MDM2 interaction is induced more strongly in infected WT than cycam1 seedlings. The levels of SA, ABA and JA are almost identical in WT and mutant seedlings, while those of 7 iso JA Ile are twice as high in the mutant compared to the WT control.