Plasma membrane transporters: summary Nitrate cytoplasm outside ve PD CO 2) transport or With(K+ etc)uptake: the CO 2H+ balance sheet outside is: Transport -1[+NO3]
cytoplasm outside -ve PD 2H+ → 2H+ ) NO3 - ) 2H+ ) NO3 - ) With C+ (K+ etc) uptake: the balance sheet outside is: -1[C+ + NO3 - ] Nitrate Plasma membrane transporters: summary cotransport cotransport or C+ pH unchanged
Plasma membrane transporters: summary Ammonium uptake depends much on the carbohydrate status in the roots NH4 and NO3 uptake is sensitive to pH NH4+ is takes place best in a neutral medium and depressed as the pH fall. The converse is true for NO3 adsorption, a more rapid uptake occurring at low pH The uptake rate of nitrate is dependent on the energy status of plant In contrast to NH4t, nitrate can be transported at high rate into shoot and can stored at high concentrations in the vacuoles NH4t uptake is promoted by NO3, but NH4* inhibited No uptake N uptake rate is highest when both n forms are in the nutrient solution
▪ Ammonium uptake depends much on the carbohydrate status in the roots. ▪ NH4 + and NO3 - uptake is sensitive to pH. NH4 + is takes place best in a neutral medium and depressed as the pH fall. The converse is true for NO3 - adsorption, a more rapid uptake occurring at low pH. ▪ The uptake rate of nitrate is dependent on the energy status of plant. ▪ In contrast to NH4 + ,nitrate can be transported at high rate into shoot and can stored at high concentrations in the vacuoles. ▪ NH4 + uptake is promoted by NO3 - ; but NH4 + inhibited NO3 - uptake. ▪ N uptake rate is highest when both N forms are in the nutrient solution. Plasma membrane transporters: summary
1 3 Forms and functions of Nin the plant Dry plant materials contains about 0.3 to 50g N/kg 1. Amino acids(5% of N in plants ), proteins(80 85%ofN in plants), nucleic acids(10% ofN in plants) 2. Proteins/enzymes regulate biochemical reactions plants 3. DNA and Rna are genetic matter 4. N is an key component of chlorophyll 5. Vitamins and secondary plant metabolism such as alkaloids(生物碱)
1.3 Forms and Functions of N in the Plant 1. Amino acids (~5% of N in plants), proteins (~80- 85% of N in plants), nucleic acids (~10% of N in plants) 2. Proteins/enzymes regulate biochemical reactions in plants. 3. DNA and RNA are genetic matter. 4. N is an key component of chlorophyll. 5. Vitamins and secondary plant metabolism such as alkaloids(生物碱）. Dry plant materials contains about 0.3 to 50g N/kg
1-4N assimilation in plant
1.4 N assimilation in plant
141 Nitrate reduction 1 Before it can be assimilated. no, must be reduced to nh Step 1-the reduction of No3 to NO2. This requires the enzyme nitrate reductase. This step occurs in the cytoplasm of the cell Step 2-the reduction of no, to NH3. This requires the enzyme nitrite reductase. This step occurs in the chloroplast or the plastid of the cell
1.4.1 Nitrate reduction 1. Before it can be assimilated, NO3 - must be reduced to NH3 . Step 1 – the reduction of NO3 - to NO2 - . This requires the enzyme nitrate reductase. This step occurs in the cytoplasm of the cell. Step 2 – the reduction of NO2 - to NH3 . This requires the enzyme nitrite reductase. This step occurs in the chloroplast or the plastid of the cell