Dehydroabietinal (DA), an abietane diterpenoid, was previously demonstrated to be a potent activator of systemic acquired resistance (SAR). DA also promotes flowering time in Arabidopsis thaliana by repressing expression of the flowering repressor FLOWERING LOCUS C (FLC) while simultaneously upregulating expression of FLOWERING LOCUS D (FLD), FLOWERING LOCUS VE (FVE) and RELATIVE OF EARLY FLOWERING 6 (REF6), a set of flowering time promoters. To further understand the mechanism underlying signaling by abietane diterpenoids, Arabidopsis mutants exhibiting reduced responsiveness to abietane diterpenoids were identified. One such mutant plant, ems2/7, exhibited SAR-deficiency and delayed flowering, which were found to be associated with two independent, but linked loci. The gene responsible for the SAR defect in ems2/7 was identified as DEFECTIVE IN SYSTEMIC DEFENSE INDUCED BY ABIETANE DITERPENOID 1 (DSA1). Similar to the missense mutant dsa1-1 identified in the mutant screen, the T-DNA insertion bearing null allele dsa1-2 exhibited SAR deficiency that could be complemented by a genomic copy of DSA1. The gene responsible for the delayed flowering phenotype of ems2/7 remains to be identified. DSA1 encodes a protein that is homologous to human protein O-fucosyltransferase 2. DSA1 is required for long-distance transport of the SAR signal. It is hypothesized that DSA1 is involved in the O-fucosylation-facilitated channeling through the ER/Golgi network of a protein involved in long distance SAR signaling. In a yeast two-hybrid screen, all the DSA1-interacting proteins identified are chloroplast-localized proteins, thus raising the interesting possibility of ER interaction with chloroplast and its potential role in SAR signaling.
| Identifer | oai:union.ndltd.org:unt.edu/info:ark/67531/metadc1944217 |
| Date | 05 1900 |
| Creators | Mohanty, Devasantosh |
| Contributors | Shah, Jyoti, Ayre, Brian, Venables, Barney, Root, Douglas, Shulaev, Vladimir |
| Publisher | University of North Texas |
| Source Sets | University of North Texas |
| Language | English |
| Detected Language | English |
| Type | Thesis or Dissertation |
| Format | Text |
| Rights | Public, Mohanty, Devasantosh, Copyright, Copyright is held by the author, unless otherwise noted. All rights Reserved. |
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