title: Inhibition of nitrogen and photosynthetic carbon assimilation of maize seedlings by exposure to a combination of salt stress and potassium-deficient stress.
abstract: The main aim of this work is to identify how the combined stresses affect the interdependent nitrogen and photosynthetic carbon assimilations in maize. Maize plants were cultivated in Meider's solution. They were subjected to salt stress and potassium deficiency in the K-present Meider's media and K-deficient Meider's media. After 5 weeks, we measured chlorophyll a fluorescence and the activities of several enzymes in metabolic checkpoints coordinating primary nitrogen and carbon assimilation in the leaves of maize. The study showed that the combination of salt stress and potassium-deficient stress more significantly decreased nitrate uptake, plant growth, the activities of nitrate reductase, glutamate dehydrogenase, glutamate synthase, urease, glutamic-pyruvic transaminase, glutamic-oxaloace transaminase, sucrose-phosphate synthase, phosphoenolpyruvate carboxylase, and the synthesis of free amino acids, chlorophyll, and protein than those of each individual stress, respectively. However, the combined stresses significantly increased the accumulation of ammonium and carbohydrate products. The combined stresses also significantly decreased the oxygen evolution, the electron transport, and the efficiency of photochemical energy conversion by photosystem II in maize seedlings. Taken together, a combination of salt stress and potassium-deficient stress impaired the assimilations of both nitrogen and carbon and decreased the photosystem II activity in maize.
authors: Medical College, Soochow University, Suzhou, 215123, China.
authors: Chunxiang
authors: C
authors: Qu
authors: Chao
authors: C
authors: Liu
authors: Yuguan
authors: Y
authors: Ze
authors: Xiaolan
authors: X
authors: Gong
authors: Mengmeng
authors: M
authors: Hong
authors: Ling
authors: L
authors: Wang
authors: Fashui
authors: F
authors: Hong
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D050260:Carbohydrate Metabolism / Q000187:drug effects; D002244:Carbon / Q000378:metabolism*; D002681:China; D002734:Chlorophyll / Q000096:biosynthesis; D002736:Chloroplasts / Q000737:chemistry / Q000378:metabolism; D013058:Mass Spectrometry; D009584:Nitrogen / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D011188:Potassium / Q000032:analysis; D011191:Potassium Deficiency / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D036226:Seedlings / Q000378:metabolism; D012964:Sodium / Q000032:analysis / Q000633:toxicity*; D013050:Spectrometry, Fluorescence; D003313:Zea mays / Q000201:enzymology / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D010940:Plant Proteins; D000644:Quaternary Ammonium Compounds; D002734:Chlorophyll; D002244:Carbon; D012964:Sodium; D009584:Nitrogen; D011188:Potassium; D010100:Oxygen