| Title: | "Arabidopsis IQD1, a novel calmodulin-binding nuclear protein, stimulates glucosinolate accumulation and plant defense" |
| Author(s): | Levy M; Wang Q; Kaspi R; Parrella MP; Abel S; |
| Address: | "Department of Plant Sciences, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA" |
| DOI: | 10.1111/j.1365-313X.2005.02435.x |
| ISSN/ISBN: | 0960-7412 (Print) 0960-7412 (Linking) |
| Abstract: | "Glucosinolates are a class of secondary metabolites with important roles in plant defense and human nutrition. To uncover regulatory mechanisms of glucosinolate production, we screened Arabidopsis thaliana T-DNA activation-tagged lines and identified a high-glucosinolate mutant caused by overexpression of IQD1 (At3g09710). A series of gain- and loss-of-function IQD1 alleles in different accessions correlates with increased and decreased glucosinolate levels, respectively. IQD1 encodes a novel protein that contains putative nuclear localization signals and several motifs known to mediate calmodulin binding, which are arranged in a plant-specific segment of 67 amino acids, called the IQ67 domain. We demonstrate that an IQD1-GFP fusion protein is targeted to the cell nucleus and that recombinant IQD1 binds to calmodulin in a Ca(2+)-dependent fashion. Analysis of steady-state messenger RNA levels of glucosinolate pathway genes indicates that IQD1 affects expression of multiple genes with roles in glucosinolate metabolism. Histochemical analysis of tissue-specific IQD1::GUS expression reveals IQD1 promoter activity mainly in vascular tissues of all organs, consistent with the expression patterns of several glucosinolate-related genes. Interestingly, overexpression of IQD1 reduces insect herbivory, which we demonstrated in dual-choice assays with the generalist phloem-feeding green peach aphid (Myzus persicae), and in weight-gain assays with the cabbage looper (Trichoplusia ni), a generalist-chewing lepidopteran. As IQD1 is induced by mechanical stimuli, we propose IQD1 to be novel nuclear factor that integrates intracellular Ca(2+) signals to fine-tune glucosinolate accumulation in response to biotic challenge" |
| Keywords: | "Amino Acid Sequence Animals Aphids Arabidopsis/*metabolism Arabidopsis Proteins/*physiology Calcium Signaling Calmodulin/metabolism Calmodulin-Binding Proteins/*physiology Feeding Behavior Gene Expression Regulation, Plant Glucosinolates/*biosynthesis Mol;" |
| Notes: | "MedlineLevy, Maggie Wang, Qiaomei Kaspi, Roy Parrella, Michael P Abel, Steffen eng Research Support, Non-U.S. Gov't England 2005/06/18 Plant J. 2005 Jul; 43(1):79-96. doi: 10.1111/j.1365-313X.2005.02435.x" |
