1. An LRR-only protein regulates abscisic acid-mediated abiotic stress responses during Arabidopsis seed germination.
- Author
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Ravindran P, Yong SY, Mohanty B, and Kumar PP
- Subjects
- Abscisic Acid metabolism, Adaptor Proteins, Signal Transducing genetics, Amino Acid Sequence, Arabidopsis drug effects, Arabidopsis Proteins chemistry, Arabidopsis Proteins genetics, Leucine-Rich Repeat Proteins, Nucleotide Motifs genetics, Phylogeny, Promoter Regions, Genetic genetics, Protein Binding drug effects, Proteins genetics, Seeds drug effects, Signal Transduction drug effects, Sodium Chloride pharmacology, Stress, Physiological genetics, Transcription Factors metabolism, Triazoles pharmacology, Abscisic Acid pharmacology, Adaptor Proteins, Signal Transducing metabolism, Arabidopsis genetics, Arabidopsis Proteins metabolism, Germination drug effects, Proteins metabolism, Seeds growth & development, Stress, Physiological drug effects
- Abstract
Key Message: LRRop-1, induced by DOF6 transcription factor, negatively regulates abiotic stress responses during Arabidopsis seed germination. The lrrop-1 mutant has reduced ABA signaling, which is part of the underlying stress-remediation mechanism. The large family of leucine-rich repeat (LRR) proteins plays a role in plant immune responses. Most LRR proteins have multiple functional domains, but a subfamily is known to possess only the LRR domain. The roles of these LRR-only proteins in Arabidopsis remain largely uncharacterized. In the present study, we have identified 44 LRR-only proteins in Arabidopsis and phylogenetically classified them into nine sub-groups. We characterized the function of LRRop-1, belonging to sub-group V. LRRop-1 encodes a predominantly ER-localized LRR domain-containing protein that is highly expressed in seeds and rosette leaves. Promoter motif analysis revealed an enrichment in binding sites for several GA-responsive and stress-responsive transcription factors. The lrrop-1 mutant seeds showed enhanced seed germination on medium containing abscisic acid (ABA), paclobutrazol and NaCl compared to the wild type (WT), demonstrating higher abiotic stress tolerance. Also, the lrrop-1 mutant seeds have lower levels of endogenous ABA, but higher levels of gibberellic acid (GA) and jasmonic acid-Ile (JA-Ile) compared to the WT. Furthermore, lrrop-1 mutant seeds imbibed with ABA exhibited reduced expression of ABA-responsive genes compared to similarly treated WT seeds, suggesting suppressed ABA signaling events in the mutant. Furthermore, chromatin immunoprecipitation (ChIP) data showed that DNA BINDING1 ZINC FINGER6 (DOF6), a negative regulator of seed germination, could directly bind to the LRRop-1 promoter and up-regulate its expression. Thus, our results show that LRRop-1 regulates ABA-mediated abiotic stress responses during Arabidopsis seed germination.
- Published
- 2020
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