Abstract
Tuber cell suspension cultures of Solanum tuberosum L. (cv. Alpha and Desiree) were established on a suitable medium in order to relate the interaction of N and salinity stress physiology at the cellular and whole plant level. Preliminary experiments showed that there was no difference in the growth response, viability and NO3- uptake under saline conditions between the Alpha (salt sensitive in the field) and the Desiree cultivar (less salt sensitive in the field). The cell suspension cultures were thus considered unsuitable as screening tools for whole plant responses and were further used as models for N uptake at the cellular level. The suspension cultures were grown on media where the sole N source was from free amino acids so as to ensure that the cells had no exposure to NO3- prior to uptake experiments. It was found that both salinity stressed (75 mmol/L NaCl) and control cells took NO3- up without the often reported <<lag phase>> and it is suggested that this <<lag phase>>, is due, at least in part, to membrane depolarization incurred by plants/cells during manipulation. Nitrate uptake is postulated to occur via a constitutive NO3- transporter requiring an induction time in the order of minutes. Salinity reduced the V(max) of NO3- uptake from 280 ± 23 nmol g-1 fm in control cells to 220 ± 14 nmol g-1 fm in the stressed cells. Over a period of 300 min it was observed that 75 mmol/L reduced NO3- uptake by approximately 60%. Supplemental Ca2+ up to 8 mmol/L, had no effect on the NO3- uptake capacity of either the control or stressed cells in contrast to what has been observed in whole plants. However, an amelioration of growth reduction and cell viability reduction in stressed cells of both cultivars was observed. It is suggested that reduced PM-ATPase activity in stressed cells is partly responsible for the NaCl-induced reduction in NO3- uptake as 75 mmol/L NaCl reduced PM-ATPase activity by approximately 30% over a 300 min time period.
Original language | English |
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Pages (from-to) | 103-109 |
Number of pages | 7 |
Journal | Journal of Plant Physiology |
Volume | 150 |
Issue number | 1-2 |
DOIs | |
State | Published - 1 Jan 1997 |
Externally published | Yes |
Keywords
- PM-ATPase
- Solanum tuberosum
- cell suspension culture
- nitrate uptake
- salinity
ASJC Scopus subject areas
- Physiology
- Agronomy and Crop Science
- Plant Science