title: Effects of 24-epibrassinolide on nitrogen metabolism in cucumber seedlings under Ca(NO(3))(2) stress.
abstract: Ca(NO(3))(2) accumulation is a major factor that limits greenhouse production in China. The present investigation was carried out to study the effect of 24-epibrassinolide (EBL) on nitrogen metabolism (including contents of NO(3)(-), NH(4)(+) and amino acids and related enzymes activities) in cucumber seedlings (Cucumis sativus L. cv. Jinyou No. 4) under 80 mM Ca(NO(3))(2) stress. This study found that exogenous EBL significantly reduced the accumulation of NO(3)(-) and NH(4)(+) by Ca(NO(3))(2), and enhanced the inactivated enzymes activities involved in the nitrogen metabolism. In addition, EBL alleviated the inhibition of photosynthesis nitrogen-use efficiency by Ca(NO(3))(2). Increased total amino acids by EBL under stress increased the precursor of proteins biosynthesis, thus promoting the biosynthesis nitrogen containing compounds. The presence of Ca(NO(3))(2) increased polyamines level, which might result from the increased content of free putrescine that is harmful to plant growth. However, exogenous EBL induced a further increase in total polyamines. The increase is likely caused by the elevated contents of conjugated and bound forms of polyamines. In summary, exogenously EBL compensated for the damage/losses by Ca(NO(3))(2) stress to some extent through the regulation of nitrogen metabolism and metabolites.
authors.affiliation: College of Horticulture, Nanjing Agricultural University, Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, Nanjing 210095, China.
authors.forename: Lingyun
authors.initials: L
authors.lastname: Yuan
authors.forename: Yinghui
authors.initials: Y
authors.lastname: Yuan
authors.forename: Jing
authors.initials: J
authors.lastname: Du
authors.forename: Jin
authors.initials: J
authors.lastname: Sun
authors.forename: Shirong
authors.initials: S
authors.lastname: Guo
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D060406:Brassinosteroids / Q000494:pharmacology*; D017610:Calcium Compounds / Q000009:adverse effects* / Q000378:metabolism; D028462:Cucumis / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D009566:Nitrates / Q000009:adverse effects* / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D010788:Photosynthesis / Q000187:drug effects; D010937:Plant Growth Regulators / Q000494:pharmacology*; D010940:Plant Proteins / Q000096:biosynthesis*; D011073:Polyamines / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects; D011700:Putrescine / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012492:Salts / Q000009:adverse effects / Q000378:metabolism; D013260:Steroids, Heterocyclic / Q000494:pharmacology*; D013312:Stress, Physiological
chemical_list: D000596:Amino Acids; D060406:Brassinosteroids; D017610:Calcium Compounds; D009566:Nitrates; D010937:Plant Growth Regulators; D010940:Plant Proteins; D011073:Polyamines; D000644:Quaternary Ammonium Compounds; D012492:Salts; D013260:Steroids, Heterocyclic; D009584:Nitrogen; C059948:calcium nitrate; D011700:Putrescine; C023623:brassinolide