Apoplastic protein pattern, hydrolases and peroxidase activity of Vicia faba cultivars as influenced by drought

Effect of drought on apoplastic protein content, protein pattern, enzymic activities and mineral concentration of Vicia faba cv Giza 40 (relatively drought-tolerant) and Vicia faba cv Giza 667 (relatively drought-sensitive) was studied. While drought decreased Na+, K+, Ca2+ concentration in leaf apoplast of Giza 40, it increased Na+ and Ca2+ concentration in case of Giza 667. Giza 40 has K+: Na+ ratio higher than that of cv Giza 667 under drought condition. The protein content of intercellular washing fluid (IWF) increased in cv Giza 40 and decreased in cv Giza 667 when subjected to drought. The elevated protein content in cv Giza 40 was the result of de novo synthesis of 13 specific polypeptides with apparent molecular mass range of 0.54 - 84.61 kDa. The declined protein content was associated with 10 newly synthesized polypeptides with molecular mass of 0.54-169.87 kDa. The changes in protein content were accompanied by a specific alteration in the activities of apoplastic enzymes in the cultivars. In general, the activities of apoplastic peroxidase and hydrolases were higher in Giza 40 than that of Giza 667 under either condition. The results indicated that the changes in leaf apoplast in response to drought are cultivar specific.