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

Abstract

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 SUBMERGENCE 1 (SUB1) locus, metabolic responses of internode elongation of deepwater rice governed by the SNORKEL 1 and 2 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 (0–24 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 (0–288 h), we found decreased amino acid levels. These metabolomic changes were opposite when compared to those in flood-tolerant rice with SUB1 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.

The hypoxia–reoxygenation stress in plants

“…Both strategies differ in terms of involvement of phytohormone signaling as well as nitrogen source utilization, and determine the degree of tolerance to hypoxia in wetland plants ( Nakamura and Noguchi, 2020 ). In rice plants under partial submergence, the escape strategy seems to require a metabolic reprogramming that involves central carbon and amino acid metabolism ( Fukushima et al , 2020 ). In turn, most terrestrial plants including several model plants such as Arabidopsis, tomato, and maize can survive under short-term hypoxia stress but cannot survive long-term O 2 deficiency and severe anaerobic conditions.…”

Shaping Durum Wheat for the Future: Gene Expression Analyses and Metabolites Profiling Support the Contribution of BCAT Genes to Drought Stress Response

“…The targeted NMR analysis of the metabolomic alteration of leaves in both Cappelli and Colosseo (Figure 7) indicated important alteration to the levels of several metabolites. Previous studies linked the involvement of several defense mechanisms, such as ROS balance, and signaling pathways with increased levels of metabolites in different plant species (Urano et al, 2009;Kochevenko et al, 2012;Pires et al, 2016;Todaka et al, 2017;Fàbregas and Fernie, 2019;Fukushima et al, 2020). In this study the metabolomic analysis was targeted to define the contrasting metabolic changes in leaves of two cultivars with different tolerance to DS and to search for correlations between the changes in metabolites classes and levels and the regulation of the newly identified TdBCAT genes.…”

“…To overcome a recurrent limitation in metabolomic experiments which is the small number of replicates, p -values have been adjusted applying the corrected FDR-adjusted p -values for multiple comparisons following the method proposed by Benjamini and Hochberg, 1995 . The application of the FDR correction to adjust the p -values is expected not only to reduce false positives, but also to minimize false negatives; the p.adjust function (R stat package) 2 was used ( Jafari and Ansari-Pour, 2019 ; Piasecka et al, 2019 ; Fukushima et al, 2020 ).…”

An updated overview of the physiological and molecular responses of rice to anoxia

“…The changes in photosynthetic pigment more into light energy harnessing (PSII:PSI, chlorophyll a:b and chlorophyll:RuBisCO) than energy quenching mechanism lead the plants to photo oxidation. Rice being a C 3 plant is thus not filled with possible drawback of over growth in vegetative tissues as found in escape strategy against flooding [77]. This is equally attributed with cellular level metabolomes those principally covers fatty acid degradation, promotion of carbohydrate transport, turnover of sucrose to starch interconversion, auxin mediated root emergences etc.…”