The results from these experi ments are summarized in Table 6 and it is apparent that most of the IPT genes selleck exhibit similar expression patterns in both transgenic and WT seedlings. The only exception appears to be IPT 8 where only 0. 5 fold expression of this gene was observed in the transgenic line. Simi larly, CKX expression in the transgenic line was also quite similar to its expression in the WT. Our results suggest that the differences in endogenous CK concentra tions previously observed in the ABR17 transgenic line may not be the result of increased IPT or decreased CKX levels. However, frequently, there is no correlation between transcript abundance and protein levels and therefore it is possible that IPT and or CKX protein con centrations may have been affected in the transgenic line resulting in increased endogenous CKs as a result of post translational processes.

However, our previously reported proteome studies on this transgenic line did not reveal any differences between transgenic and WT seedlings with respect to the levels of these proteins. It is possible Inhibitors,Modulators,Libraries that the activity of neither IPT nor CKX is responsible for the increased endogenous concentrations of CKs in the ABR17 transgenic lines and the increased endogenous CKs previously reported in the ABR17 trans genic lines may be the result of tRNA degradation by the previously demonstrated RNase activity of pea ABR17 protein. Thus, an increase in free cellular CK would not necessarily involve enhanced IPT or reduced CKX activity. rather it may reflect an increased access to existing, yet tRNA bound, CK.

Conclusion We have demonstrated that pea ABR17 cDNA expression modulates the level Inhibitors,Modulators,Libraries of a number of transcripts related to plant defense, growth and development, which may explain the observed phenotypic differences between WT and ABR17 transgenic A. thaliana. The gene expression of many transcription factors and defense responsive genes like Hsps and PDFs showed different degree Inhibitors,Modulators,Libraries and kind of response between salt treated ABR17 transgenic and WT A. thaliana, which explains the observed enhanced germi nation and early seedling vigor in ABR17 transgenic lines, compared to its WT counterpart. Many of the genes exhib iting a 2 fold or higher increase in transcript abundance are known CK responsive genes providing additional evi dence of a role for CKs in ABR17 function.

Furthermore, a detailed expression analysis of IPTs and CKXs revealed that the levels of Inhibitors,Modulators,Libraries these transcripts were similar in both WT and transgenic seedlings, suggesting the possibility that ABR17 modulates Inhibitors,Modulators,Libraries endogenous CKs through an, as of yet, uncharacterized mechanism including the possible degra dation of tRNAs which HTC contain CK moieties. These possibilities are currently being investigated in our labora tory. Methods Plant material and growth conditions Transformation of A.