RING finger E3 ligase gene, Oryza sativa Delayed Seed Germination 1 (OsDSG1), controls seed germination and stress responses in rice

• Published in: Plant molecular biology Vol. 74; no. 4-5; pp. 467 - 478
• Main Authors: Park, Gi-Gyeong, Park, Jong-Jin, Yoon, Jinmi, Yu, Sun-Nam, An, Gynheung
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 01.11.2010; Springer Netherlands; Springer Nature B.V
• Subjects: ABA signaling; Abiotic stresses; Abscisic Acid - metabolism; Arabidopsis; Biochemistry; Biomedical and Life Sciences; Botany; E3 ligase; Germination; Life Sciences; Molecular biology; Mutation; Oryza - enzymology; Oryza - genetics; Oryza - physiology; Oryza sativa; Plant biology; Plant Leaves - enzymology; Plant Leaves - genetics; Plant Leaves - physiology; Plant Pathology; Plant Proteins - chemistry; Plant Proteins - genetics; Plant Proteins - physiology; Plant Roots - enzymology; Plant Roots - genetics; Plant Roots - physiology; Plant Sciences; Plants, Genetically Modified - growth & development; Plants, Genetically Modified - metabolism; Rice; RING Finger Domains; RNA Interference; RNA, Messenger; seed germination; Seeds; Seeds - enzymology; Seeds - genetics; Seeds - growth & development; Signal Transduction; Stress, Physiological; Two-Hybrid System Techniques; Ubiquitin-Protein Ligases - chemistry; Ubiquitin-Protein Ligases - genetics; Ubiquitin-Protein Ligases - physiology; ABA signaling; Abiotic stresses; E3 ligase; Rice; Seed germination
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1007/s11103-010-9687-3

Seed germination is an important character for plant growth and seed quality. We identified a rice mutant that was delayed in its germination. There, T-DNA was inserted into Oryza sativa Delayed Seed Germination 1 (OsDSG1), causing a recessive null mutation. Overexpression of the gene enhanced seed germination. OsDSG1 is most similar to Arabidopsis AIP2, an E3 ligase targeting ABI3.Yeast two-hybrid experiments showed that our OsDSG1 binds to OsABI3, indicating that OsDSG1 is a rice ortholog of AIP2. Self-ubiquitination assay indicated that bacterially expressed OsDSG1 protein has E3 ubiquitin ligase activity. Real-time PCR analysis revealed that OsDSG1 was expressed in leaves and roots, and strongly in developing seeds. In addition to the delayed-germination phenotype, mutant plants were shorter and had greater tolerance to high-salt and drought stresses. In the osdsg1 mutant, transcript levels of ABA signaling genes and ABA responsive genes were significantly increased. By contrast, expressions of OsGAMYB and its downstream genes that encode hydrolytic enzymes were markedly reduced. These observations support that OsDSG1 is a major regulator of ABA signaling in germinating seeds. Finally, we observed that the germination rates of various rice cultivars depended upon the transcript levels of OsDSG1 and other ABA-signaling genes.