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1 Uludag Uni ver sity, Fac ulty of Ag ri cul ture, De part ment of Hor ti cul ture, Ab stractEf fects of salt stress on the ac tiv ity of peroxidase (PRX) isozyme and leaf pro teins were stud ied in the three straw berry va ri et ies, Camarosa, Tioga and Chan dler. Plants were wa tered with mod i fied 1/3 Hoagland nu tri ent so lu tion con tain ing 0 (con trol), 8.5, 17.0 and 34.0 mM NaCl for 30 days fallowing 20 days ac cli ma tion. PRX ac tiv ity was as sayed in leaf ex tracts and PRX pro files of con trol and salt treated plants were performed by na tive polyacrylamide gel elec tro pho re sis (PAGE).Dur ing the salt stress Tioga and Camarosa tol er ated the cel lu lar dam age with less elec tro lyte leak age while Chandler ex hib ited a se vere cel lu lar dam age with the high est (87.5 % in 34.0 mM NaCl treat ment) elec tro lyte leak age. To tal sol uble pro tein con tent was de creased by sa lin ity in Tioga (from 11.35 to 5.86 mg·g -1 DW) and Chan dler (from 9.35 to 3.90 mg·g -1 DW) while it was al most un changed in Camarosa. Salt stress in creased to tal and spe cific PRX ac tiv ity as com pared with the con trol in all the va ri et ies. In na tive PAGE, one ba sic isoperoxidase band (Rf=0.27) was ob served com monly with dif fer ent band in ten sity in all the treat ments. There fore, it might be as so ci ated with lig ni fi ca tion and re cov ery of cell mem brane dam age in straw berry plants un der salt stress.

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SUMMARYSeasonal patterns of antioxidative enzymes and proteins and their relations to cold-hardiness of nine olive (Olea europaeaL.) cultivars (Ascolona, Domat, Gemlik, Hojoblanca, Lecquest, Manzanilla, Meski, Samanli and Uslu) are documented in the current study. Fully expanded, uniformly sized leaves from 2-year-old shoots of the cultivars were collected from 20-year-old trees in cold-acclimated (CA, in January) and non-acclimated (NA, in July) stages. Leaf samples were exposed to low temperature at 4, −5, −10 and −20°C for 12 h to determine their cold-hardiness (LT50; assessed by electrolyte leakage). Cold-acclimation produced an increase in freezing tolerance of all cultivars (by lowering LT50). Domat and Lecquest were found to have the highest cold-hardiness among the nine cultivars investigated. Ascolona, Gemlik, Hojoblanca had moderate cold-hardiness, while Samanli, Meski, Uslu and Manzanilla were more sensitive. Activities of catalase (CAT: EC 1·11·1·6), ascorbate peroxidase (APX: EC 1·11·1·11) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase significantly varied depending on the cold-acclimation stage and the cold-hardiness level of the cultivars. Activities of the three antioxidative enzymes and total soluble proteins (TSP) were higher in the CA stage than in the NA stage. Although no accumulation of major polypeptides, except a 23 kDa protein, was detected either in CA samples or NA samples by SDS-PAGE, anti-dehydrin immunoblots revealed that the 43 and 23 kDa polypeptides were detectable during cold-acclimation of olive cultivars. Accumulation of both 43 and 23 kDa dehydrin was significantly higher in the CA stage than in the NA stage in all cultivars. Accumulation of 43 kDa dehydrin was correlated with cold-hardiness of the cultivars, while 23 kDa dehydrin was considered as cultivar-dependent since its accumulation was not parallel to LT50values of the cultivars. Indeed, the tissues of cvs Domat, Lecquest, Ascolona, Hojoblanca and Gemlik were found to enhance the structural stability of cellular membranes in the CA stage by increasing both the activity of such enzymes as CAT, APX and NADPH oxidase to activate the antioxidative systems and the expression of 43 kDa dehydrins.