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An orthologous transcriptional signature differentiates responses towards closely related chemicals in Arabidopsis thaliana and brassica napus
Citation:
Das, M., G. Haberer, G. Welzl, M. T. Mader, A. R. Schaffner, J. R. REICHMAN, L. S. WATRUD, T. G. PFLEEGER, D. M. OLSZYK, F. F. Aceituno, AND R. A. Gutierrez. An orthologous transcriptional signature differentiates responses towards closely related chemicals in Arabidopsis thaliana and brassica napus. Presented at 20th International Conference on Arabidopsis Researach, Edinburgh, UK, June 30 - July 04, 2009.
Impact/Purpose:
Herbicides are structurally diverse chemicals that inhibit plant-specific targets, however their off-target and potentially differentiating side-effects are less well defined.
Description:
Herbicides are structurally diverse chemicals that inhibit plant-specific targets, however their off-target and potentially differentiating side-effects are less well defined. In this study, genome-wide expression profiling based on Affymetrix AtH1 arrays was used to identify discriminating responses of Arabidopsis thaliana to five related chemicals that target two different branches of amino acid biosynthesis. The compounds included glyphosate that targets 5-enolpyruvylshikimate-3-phosphate synthase and four diverse acetolactate synthase (ALS) inhibiting compounds. The ALS inhibitors comprised three different chemical classes as well as two compounds based on the same, sulfonylurea backbone. In contrast to glyphosate, which affected only a few transcripts, ALS inhibitors led to numerous transcriptional changes which indicated off-target effects related to C-metabolism, secondary metabolism, cell wall modification and growth. The expression pattern of a set of 101 genes provided a specific, composite signature that was distinct from other major stress responses and differentiated between chemicals targeting the same enzyme (ALS) even between those possessing the same structural backbone (sulfonylurea). Despite the complications due to a genome triplication event during evolution of Brassica species, a set of homologous genes was identified in Brassica napus that also exhibited a similar expression pattern distinguishing the exposure to the five herbicides. Hence, the ability of a limited number of orthologous genes to classify and differentiate responses to closely related chemicals in A. thaliana and B. napus underscores the validity of such a feature and the transferability of a complex transcriptional signature across species. At1g02410, At1g04040, At1g15420, At1g31970, At1g53580, At1g62560, At1g66970, At1g72030, At1g77120, At2g27500, At2g28790, At2g29310, At3g14600, At3g16250, At4g02290, At4g14110, At5g03610, At5g13630, At5g17170, At5g42150, At5g51820, At5g52820, At5g59310