Exogenous glutamate rapidly induces the expression of genes involved in metabolism and defense responses in rice roots

• Published in: BMC genomics Vol. 18; no. 1; p. 186
• Main Authors: Kan, Chia-Cheng, Chung, Tsui-Yun, Wu, Hsin-Yu, Juo, Yan-An, Hsieh, Ming-Hsiun
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 17.02.2017; BioMed Central
• Subjects: Abiotic stress; Amino acids; Ammonium; Ammonium nitrate; Aquatic plants; Carbon; Cellular stress response; Chlorophyll; Dehydrogenases; Dose-Response Relationship, Drug; Gene expression; Gene Expression Regulation, Plant - drug effects; Genes; Genetic aspects; Genomics; Glutamate; Glutamic Acid - metabolism; Glutamic Acid - pharmacology; Glutamine; Kinases; Metabolism; Metabolites; Nervous system; Nitrogen; Nitrogen - pharmacology; Nutrition; Oryza - drug effects; Oryza - genetics; Oryza - metabolism; Oryza - physiology; Plant nutrition; Plant Roots - drug effects; Plant Roots - genetics; Plant Roots - metabolism; Plant Roots - physiology; Protein biosynthesis; Protein synthesis; Protein turnover; Rice; Roots; Roots (Botany); Seedlings; Seedlings - drug effects; Seedlings - growth & development; Signal transduction; Signaling; Transcription factors; Transcription Factors - metabolism; Vitamin B; Signal transduction; Gene expression; Glutamate; Metabolism; Transcription factor; Defense response; Rice
• ISSN: 1471-2164; 1471-2164
• DOI: 10.1186/s12864-017-3588-7

Glutamate is an active amino acid. In addition to protein synthesis and metabolism, increasing evidence indicates that glutamate may also function as a signaling molecule in plants. Still, little is known about the nutritional role of glutamate and genes that are directly regulated by glutamate in rice. Exogenous glutamate could serve as a nitrogen nutrient to support the growth of rice seedlings, but it was not as effective as ammonium nitrate or glutamine. In nitrogen-starved rice seedlings, glutamate was the most abundant free amino acid and feeding of glutamate rapidly and significantly increased the endogenous levels of glutamine, but not glutamate. These results indicated that glutamate was quickly metabolized and converted to the other nitrogen-containing compounds in rice. Transcriptome analysis revealed that at least 122 genes involved in metabolism, transport, signal transduction, and stress responses in the roots were rapidly induced by 2.5 mM glutamate within 30 min. Many of these genes were also up-regulated by glutamine and ammonium nitrate. Still, we were able to identify some transcription factor, kinase/phosphatase, and elicitor-responsive genes that were specifically or preferentially induced by glutamate. Glutamate is a functional amino acid that plays important roles in plant nutrition, metabolism, and signal transduction. The rapid and specific induction of transcription factor, kinase/phosphatase and elicitor-responsive genes suggests that glutamate may efficiently amplify its signal and interact with other signaling pathways to regulate metabolism, growth and defense responses in rice.