EFFECT OF AGING, ABIOTIC AND BIOTIC STRESS UPON UBIQUITINATION IN YOUNG BARLEY PLANTS

Western analysis with anti-ubiquitin antibodies revealed specific vari ations of ubiquitin conjugates in Hordeum vulgare cv. Carina during ag ing, drought-stress and infection with Erysiphe graminis. Leaf aging i s accompanied by an increase in the relative amount of ubiquitin conju gates with molecular masses of 15 and 24 kDa, whereas the amount of an other immunoreactive protein (53 kDa) decreases. These three conjugate s, especially the 53 kDa protein, are far less detectable under condit ions of drought. Western analysis of proteins from infected leaves sho ws a stronger signal of a 29 kDa conjugate, and a weaker one of a 30 k Da conjugate. Beyond these, an additional ubiquitin conjugate of 20 kD a was detected.