Responses of Transgenic Tobacco Plants with Increased Proline Content to Drought and/or Heat Stress

Pospíšilová J., Haisel D., Vaňková R.

Klíčová slova: Carotenoids, Chlorophyll, Net Photosynthetic Rate, Stomatal Conductance, Transpiration Rate, Xanthophyll Cycle Pigments
Abstrakt: Transgenic tobacco plants (M51-1) constitutively over-expressing a modified gene for the proline biosynthetic enzyme Δ2-pyrroline-5-carboxylate synthetase (P5CSF129A) and the corresponding wild-type plants (WT) were compared during drought or heat stress and under combination of both stresses. The proline content in M51-1 was several times higher than in WT plants. Under optimal conditions, the transpiration rate and stomatal conductance of M51-1 plants were lower than those in WT plants. The differences in net photosynthetic rate were not significant and water use effi-ciency and contents of chlorophyll and xanthophyll cycle pigments were higher in M51-1 than in WT plants. Drought induced by cessation of watering for 7 d resulted in decrease of all gas exchange parameters and chlorophyll content, but in an increase of the content of xanthophyll cycle pigments and degree of their de-epoxidation. After application of heat stress (40°C/60 min) to control or water-stressed plants the gas exchange parameters decreased considerably. Short-term heat stress alone, however, did not affect pigment contents. The responses of M51-1 and WT plants to the tested stresses did not differ significantly. Therefore, a decisive contribution of elevated proline content to drought or heat stress tolerance of tobacco was not proved.
Autoři z ÚEB: Daniel Haisel, Jana Pospíšilová, Radomíra Vaňková