Integration of Auxin and Salt Signals by the NAC Transcription Factor NTM2 during Seed Germination in Arabidopsis

• Published in: Plant physiology (Bethesda) Vol. 156; no. 2; pp. 537 - 549
• Main Authors: Park, Jungmin, Kim, Youn-Sung, Kim, Sang-Gyu, Jung, Jae-Hoon, Woo, Je-Chang, Park, Chung-Mo
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01-06-2011
• Subjects: Abscisic acid; Arabidopsis - drug effects; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Auxins; Biological and medical sciences; Cell Membrane - drug effects; Cell Membrane - metabolism; DEVELOPMENT AND HORMONE ACTION; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant - drug effects; Genes; Genes, Plant - genetics; Germination; Germination - drug effects; Germination - genetics; Indoleacetic Acids - metabolism; Indoleacetic Acids - pharmacology; Mutation - genetics; Plant physiology and development; Plants; Promoter Regions, Genetic - genetics; Protein Binding - drug effects; Proteins; Salinity; Salts; Seed germination; Seeds - drug effects; Seeds - genetics; Seeds - growth & development; Signal Transduction - drug effects; Signal Transduction - genetics; Sodium Chloride - metabolism; Sodium Chloride - pharmacology; Transcription factors; Transcription Factors - genetics; Transcription Factors - metabolism; Transgenic plants; Auxin; Seeds; Germination; Salinity; Arabidopsis thaliana; Salt; Plant physiology; Cruciferae; Dicotyledones; Angiospermae; Spermatophyta; Experimental plant; Transcription factor
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.111.177071

Seed germination is regulated through elaborately interacting signaling networks that integrate diverse environmental cues into hormonal signaling pathways. Roles of gibberellic acid and abscisic acid in germination have been studied extensively using Arabidopsis (Arabidopsis thaliana) mutants having alterations in seed germination. Auxin has also been implicated in seed germination. However, how auxin influences germination is largely unknown. Here, we demonstrate that auxin is linked via the IAA30 gene with a salt signaling cascade mediated by the NAM-ATAF1/2-CUC2 transcription factor NTM2/Arabidopsis NAC domain-containing protein 69 (for NAC with Transmembrane Motif 1) during seed germination. Germination of the NTM2-deficient nim2-1 mutant seeds exhibited enhanced resistance to high salinity. However, the salt resistance disappeared in the ntm2-1 mutant overexpressing the IAA30 gene, which was induced by salt in a NTM2-dependent manner. Auxin exhibited no discernible effects on germination under normal growth conditions. Under high salinity, however, whereas exogenous application of auxin further suppressed the germination of control seeds, the auxin effects were reduced in the ntm2-1 mutant. Consistent with the inhibitory effects of auxin on germination, germination of YUCCA 3-overexpressing plants containing elevated levels of active auxin was more severely influenced by salt. These observations indicate that auxin delays seed germination under high salinity through cross talk with the NTM2-mediated salt signaling in Arabidopsis.