Physiological and biochemical effect of synthetic 1,2,3-Thiadiazole [1,3-Bis[4-(1,2,3-thiadiazol-4-yl) phenoxy]propane] on wheat (Triticum durum L.) seedlings growth and metabolism

Thiadiazole compounds and their derivatives cause many structural, physiological and developmental changes as well as metabolic pathways associated with carbon and nitrogen metabolism and the redox state inside plant tissues. In this study, physiological and biochemical effects of 0, 5, 25 and 50 μg/L of synthetic 1,2,3-Thiadiazole [1,3-Bis[4-(1,2,3-thiadiazol-4-yl) phenoxy]propane] compound on two wheat (Triticum durum L.) cultivars seedlings were examined in terms of seed germination, plant growth, oxidative damage, GABA level, total carbohydrates and protein contents and chlorophyll contents. Seed germination was completely inhibited except at 5 μg/L, which resulted in germination percentage of 37 % for Hurani75 and 50 % for Um Qayes compared to 90 % and 94 % seed germination for both cultivars, respectively, at no treatment (0 μg/L). Shoot fresh weight and dry mass were significantly reduced under all treatments with negative correlation compared to no treatment. The accumulation of MDA was significantly higher in Um Qayes than Hurani75 cultivar under all treatments. Significant accumulation of GABA in both cultivars, significant reduction in total protein level and carbohydrates and chlorophyll contents in response to all treatments were also found. The high accumulation of GABA and reduction in total protein and carbohydrates contents suggested that GABA shunt might act as alternative pathway in Carbon and Nitrogen metabolism through generating Carbon fluxes to TCA cycle, enhancing basal Nitrogen assimilation and counteract the oxidative damage to restrict ROS increase in response to the synthetic 1,2,3-Thiadiazole [1,3-Bis[4-(1,2,3-thiadiazol-4-yl) phenoxy]propane] compound treatment in durum wheat seedlings.