Overproduction of Two Stress-Induced Alfalfa Proteins Provides Tolerance Against Wide Range of Stresses in Transgenic Plants

Gabor V. Horvath1,2, Attila Oberschall1,2, Maria Deak1,2, Sholpan Davletova1, Katalin Torok1, Laszlo Sass1, Imre Vass1, Eva Hideg1, Balazs Barna3, Zoltan Kiraly3, Attila Feher1,2 and Denes Dudits1,2

1Institute of Plant Biology, Biological Research Center, Szeged, Hungary
2Biotechnology Institute of Bay Zoltan Applied Research Foundation, Szeged, Hungary
3Institute of Plant Protection of the Hungarian Academy of Sciences, Budapest, Hungary

 

Rapid accumulation of reactive oxygen species (ROS) significantly contributes to the damage of crop plants under biotic and abiotic stresses. Production of the most harmful ROS, the hydroxyl radical depends on the presence of free Fe2+. Therefore, we have tested, whether the synthesis of iron-binding protein, ferritin in green tissues can protect the plant cells from oxidative stress. Transgenic tobacco plants accumulating alfalfa ferritin in vegetative tissues showed resistance against paraquat and reduced necrotic symptoms after viral, fungal and bacterial infections and fusaric acid treatment.

We have cloned an alfalfa cDNA encoding a homologous protein of aldose/aldehyde reductases. The alfalfa enzyme showed enzymatic activity with DL-glyceraldehyde and 4-hydroxy-nonenaI (HNE). Since HNE is one of the major cytotoxic lipid- peroxide degradation product, this protein is expected to provide protective function under stress conditions. Indeed, the tobacco transformants expressing the alfalfa cDNA could tolerate paraquat, heavy metal, hydrogen-peroxide and sodium chloride treatment. These transgenic plants could also resist UV-B irradiation and a long period (35 days) of water deficiency with improved recovery after rehydration.