Metabolite and Phytohormone Profiling Illustrates Metabolic Reprogramming as an Escape Strategy of Deepwater Rice during Partially Submerged Stress

• Main Authors: Atsushi Fukushima, Takeshi Kuroha, Keisuke Nagai, Yoko Hattori, Makoto Kobayashi, Tomoko Nishizawa, Mikiko Kojima, Yoshinori Utsumi, Akira Oikawa, Motoaki Seki, Hitoshi Sakakibara, Kazuki Saito, Motoyuki Ashikari, Miyako Kusano
• Format: Article
• Language: English
• Published: MDPI AG 2020-02-01
• Series: Metabolites
• Subjects: deepwater rice; anoxia; hypoxia; snorkel; flooding stress; metabolome; glycolysis
• Online Access: https://www.mdpi.com/2218-1989/10/2/68

Rice varieties that can survive under submergence conditions respond to flooding either by enhancing internode elongation or by quiescence of shoot elongation. Despite extensive efforts to identify key metabolites triggered by complete submergence of rice possessing <i>SUBMERGENCE 1</i> (<i>SUB1</i>) locus, metabolic responses of internode elongation of deepwater rice governed by the <i>SNORKEL 1</i> and <i>2</i> genes remain elusive. This study investigated specific metabolomic responses under partial submergence (PS) to deepwater- (C9285) and non-deepwater rice cultivars (Taichung 65 (T65)). In addition, we examined the response in a near-isogenic line (NIL-12) that has a C9285 genomic fragment on chromosome 12 introgressed into the genetic background of T65. Under short-term submergence (0&#8722;24 h), metabolite profiles of C9285, NIL-12, and T65 were compared to extract significantly changed metabolites in deepwater rice under PS conditions. Comprehensive metabolite and phytohormone profiling revealed increases in metabolite levels in the glycolysis pathway in NIL-12 plants. Under long-term submergence (0&#8722;288 h), we found decreased amino acid levels. These metabolomic changes were opposite when compared to those in flood-tolerant rice with <i>SUB1</i> locus. Auxin conjugate levels related to stress response decreased in NIL-12 lines relative to T65. Our analysis helped clarify the complex metabolic reprogramming in deepwater rice as an escape strategy.