Fig. 8.

The regulation of proline content in source leaves of B. napus at the vegetative growth phase. Protein degradation in source leaves produces proline, which is not accumulated compared with leaves having a low sink/source balance. Our results showed that net proline biosynthesis flux was reduced in source leaves, whereas the maximal proline degradation capacity was weakly affected by the sink/source balance of the leaves. Consequently, proline arising from protein degradation could be exported from source leaves to organs having a low sink/source balance. Overall, our results suggest that proline catabolism plays a minor role in nitrogen remobilization processes in source leaves. (This figure is available in colour at JXB online.)