title: The role of 24-epibrassinolide in the regulation of photosynthetic characteristics and nitrogen metabolism of tomato seedlings under a combined low temperature and weak light stress.
abstract: In the present study, we aimed to investigate the effects of exogenous 24-epibrassinolide (EBR) on growth, photosynthetic characteristics, chlorophyll fluorescence imaging, and nitrogen metabolism of tomato leaves under low temperature and weak light conditions. The results showed that foliar application of EBR significantly alleviated the inhibition of plant growth, and increased the fresh and dry weights of tomato plants under a combined low temperature and weak light stress. Moreover, EBR also increased the net photosynthetic rate (Pn), light saturation point (LSP), maximal quantum yield of PSII photochemistry (Fv/Fm), actual photochemical efficiency of PSII (ФPSII), and photochemical quenching coefficient (qP), but decreased the intercellular CO2 concentration (Ci), light compensation point (LCP) and apparent quantum efficiency (AQE) under low temperature and weak light conditions. In addition, application of EBR to tomato leaves significantly enhanced the activities of nitrate reductase (NR), glutamate dehydrogenase (GDH), glutamine synthetase (GS), and glutamate synthase (GOGAT), but decreased the ammonium content and nitrite reductase (NiR) activity. We observed that EBR remarkably increased the contents of aspartic acid, threonine, serine, glycine, and phenylalanine, while decreasing the accumulation of cysteine, methionine, arginine, and proline under a combined low temperature and light stress. These results suggest that EBR could alleviate the combined stress-induced harmful effects on photosynthesis and nitrogen metabolism, thus leading to improved plant growth.
authors.affiliation: College of Horticulture, Nanjing Agricultural University, Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, Nanjing 210095, People's Republic of China; Facility Horticulture Institute, Nanjing Agricultural University, Suqian 223800, People's Republic of China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Shu
authors.affiliation: College of Horticulture, Nanjing Agricultural University, Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, Nanjing 210095, People's Republic of China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Tang
authors.affiliation: College of Horticulture, Nanjing Agricultural University, Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, Nanjing 210095, People's Republic of China.
authors.forename: Yinghui
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: College of Horticulture, Nanjing Agricultural University, Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, Nanjing 210095, People's Republic of China; Facility Horticulture Institute, Nanjing Agricultural University, Suqian 223800, People's Republic of China.
authors.forename: Jin
authors.initials: J
authors.lastname: Sun
authors.affiliation: College of Horticulture, Nanjing Agricultural University, Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, Nanjing 210095, People's Republic of China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhong
authors.affiliation: College of Horticulture, Nanjing Agricultural University, Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, Nanjing 210095, People's Republic of China; Facility Horticulture Institute, Nanjing Agricultural University, Suqian 223800, People's Republic of China. Electronic address: srguo@njau.edu.cn.
authors.forename: Shirong
authors.initials: S
authors.lastname: Guo
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D064751:Ammonium Compounds / Q000032:analysis; D060406:Brassinosteroids / Q000494:pharmacology*; D002734:Chlorophyll / Q000378:metabolism; D003080:Cold Temperature; D005453:Fluorescence; D005740:Gases / Q000378:metabolism; D005969:Glutamate Dehydrogenase / Q000378:metabolism; D005970:Glutamate Synthase / Q000378:metabolism; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D008027:Light; D018551:Solanum lycopersicum / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects; D050901:Nitrate Reductase / Q000378:metabolism; D009566:Nitrates / Q000032:analysis; D009572:Nitrite Reductases / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D017785:Photons; D010788:Photosynthesis / Q000187:drug effects* / Q000528:radiation effects; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism / Q000528:radiation effects; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects; D013260:Steroids, Heterocyclic / Q000494:pharmacology*; D013312:Stress, Physiological / Q000187:drug effects / Q000528:radiation effects
chemical_list: D000596:Amino Acids; D064751:Ammonium Compounds; D060406:Brassinosteroids; D005740:Gases; D009566:Nitrates; D013260:Steroids, Heterocyclic; D002734:Chlorophyll; D005970:Glutamate Synthase; D005969:Glutamate Dehydrogenase; D009572:Nitrite Reductases; D050901:Nitrate Reductase; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen; C023623:brassinolide
keywords: 24-Epibrassinolide; Low temperature and weak light; Nitrogen metabolism; Photosynthesis; Tomato