This model calculates biomass production from intercepted photosynthetically active radiation and grain growth from simple partitioning rules (Jamieson et al., 1998b) utilising nitrogen response and phenological development sub-models described by Jamieson and Semenov (2000).
Due to the inability of the Δ areA mutant to utilise various nitrogen sources, no additional resistance marker was required and transformants were regenerated on media containing nitrate as the sole nitrogen source.
When utilising complex nitrogen sources, A. fumigatus secretes proteases, and increases expression of amidase, aminotransferase, and amino acid and peptide transporter genes [ 40, 41].
The reason for the inability of ProDH1 mutants to utilise Pro as nitrogen source, despite a functional ProDH2 copy, could be that ProDH2 is not in the correct subcellular localisation to support Pro degradation.
Subcellular localisation and enzymatic functionality of ProDH2 indicated that the low expression level and/or the tissue specificity were responsible for the inability of pdh1-1 mutonts to utilise Pro as nitrogen source.
Because the direct products of cyanase action are ammonia and bicarbonate, cyanate is utilised as a nitrogen and carbon source in some organisms [17], [24].
Fungi can utilise various sources of nitrogen, from easily assimilated sources (e.g., ammonium and glutamate), to more complex secondary sources including amino acids and proteins [ 40, 58].
The products of the gab operon (which comprises gabT (γ-aminobutyrate transferase), gabD (SSADH), gabP (GABA permease) and gabC (a regulatory gene) [22]) drive GABA catabolism and permit cells to utilise GABA as the sole nitrogen source [23], [24].
These findings indicated that inhibitory effects of Orn and Arg were overcome by Gln, but oat mutants were not or only poorly able to utilise Arg or Orn as nitrogen sources.
In a direct comparison of pdh1, pdh2 and p5cdh mutants, we observed that pdh1 and p5cdh mutants were unable to utilise Pro as the sole nitrogen source, whereas pdh2 mutants grew equally well as the corresponding wildtype.
