1. Diurnal changes in C N metabolism and response of rice seedlings to UV-B radiation
- Author
-
Keewoong Park, Deog-Bae Lee, Yangmin X. Kim, Seul-Bi Lee, Hye-Jin Yun, Jwa-Kyung Sung, Yejin Lee, and Sunhyung Lim
- Subjects
0106 biological sciences ,0301 basic medicine ,Sucrose ,Ultraviolet Rays ,Physiology ,Starch ,Plant Science ,01 natural sciences ,Gas Chromatography-Mass Spectrometry ,03 medical and health sciences ,chemistry.chemical_compound ,Gene expression ,Irradiation ,Food science ,chemistry.chemical_classification ,Oryza sativa ,food and beverages ,Primary metabolite ,Oryza ,Metabolism ,Circadian Rhythm ,Amino acid ,Plant Leaves ,030104 developmental biology ,chemistry ,Seedlings ,Carbohydrate Metabolism ,Agronomy and Crop Science ,010606 plant biology & botany - Abstract
Plants regulate a number of primary metabolites, including carbohydrates, organic acids, and amino acids, in response to UV-B radiation. Therefore, it is essential to understand the time-dependent response of rice plants to UV-B stress. This study focused on the response of plants to UV-B at different leaf developmental phases (emerging, growing, and maturing) in an attempt to fully comprehend the metabolic shift. We analyzed the expression levels of genes related to starch/sucrose metabolism in the leaf blades of rice seedlings (Oryza sativa L. “Saechuchenog”) exposed to UV-B irradiation for short (1 day) and long terms (5 days) using quantitative real-time polymerase chain reaction. We also examined the diurnal variations in the contents of primary metabolites using an established GCTOF-MS (gas chromatography time of flight-mass spectrometry) method. The results showed that the levels of primary metabolites were largely dependent upon the diurnal rhythm and leaf developmental phase. The young leaves (sink) produced and accumulated starch rather than sucrose. The short-term (4 h, 1 day) UV-B exposure inhibited sucrose synthesis, which could be the first target of UV-B radiation. Following short- and long-term (5 days) exposure to UV-B radiation, the dynamic response of primary metabolites was evaluated. It was found that the content of carbohydrates decreased throughout the period of exposure to UV-B stress, especially in terms of sucrose concentration. However, the content of the majority of amino acids increased after an early decrease. Our data revealed that the metabolic response, as well as the gene expression, differed with the period (intensity) of exposure to UV-B radiation and with the phase of leaf development. These findings provide new insights for a better understanding of the metabolic response of a variety of plant species exposed to a wide range of UV-B radiation.
- Published
- 2018