Expression of enzyme activities and transcripts required for nitrate assimilation in maize (Zea mays L. A188 × BMS) suspension cell cultures

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• 作者：Redinbaugh ; Margaret G. ; Ritchie ; Steven W. ; Hendrix ; K. W. ; MacKown ; Charles T. ; Campbell ; W.H.
• 关键词：Zea mays ; Suspension cell culture ; Cell growth ; Nitrate reductase ; Nitrate assimilation ; Nitrite reductase ; Glucose-6-phosphate dehydrogenase ; 6-Phosphogluconate dehydrogenase ; Gene expression ; Enzyme activity
• 刊名：Plant Science
• 出版年：1996
• 出版时间：September 21, 1996
• 年：1996
• 卷：119
• 期：1-2
• 页码：169-181
• 全文大小：940 K

文摘

The response of a rapidly growing, transformable maize suspension cell culture line (Zea mays L. A188 × BMS) to changes in media N and NO⁻₃ treatment was examined. Growth, N content, enzyme activities and transcript levels were measured in cells transferred to N-rich media (N6) or to media lacking N (N-free). Transferring cells to N-free media had little impact on cell growth (fresh and dry weight). However, reduced N, soluble protein, and total RNA per g dry weight were about 50 % lower than in cells transferred to N6 media. Cellular NO⁻₃, nitrate reductase (NR) and nitrite reductase (NiR) activity declined rapidly when cells were transferred to N-free media. Within 24 h after transfer to N-free media, treatment with 1 mM KNO₃ increased NADH: NR, NAD(P)H: NR, and NiR activities, and NR transcript levels. Cells transferred to N6 media did not respond to KNO₃ treatment. Three days after transfer to N-free media, NR transcript levels increased rapidly and transiently in response to low concentrations of NO⁻₃. This response was not prevented by the cytoplasmic protein synthesis inhibitor, cycloheximide. The similarity between the response of the N-starved A188 × BMS cell culture and maize roots to environmental NO⁻₃ indicated that the cell cultures provide a uniform, easily manipulable system for the study of NO⁻₃ signal transduction processes.