Proline is involved in water stress responses of Lotus corniculatus nitrogen fixing and nitrate fed plants

Water stress induced proline accumulation in Lotus corniculatus regardless of the nitrogen source provided to plants, although this accumulation was higher in nitrogen fixing plants. Enzymes related to synthesis and oxidation of proline were analysed. Fd-GOGAT activity and Fd-GOGAT protein content increased in response to water stress in contrast to PDH activity, which decreased under such condition. However, rehydration for 6 h induced an increment in PDH activity. The differential effect of water deficit on enzymes involved in the proline pathway in L. corniculatus plants growing under different nitrogen regimes is discussed. The possible role of nitrate as an osmoprotectant in the place of proline is also considered.