Triangular interplay between ROS, ABA and GA in dormancy alleviation of Bunium persicum seeds by cold stratification

Seeds of Bunium persicum (Boiss.) B. Fedtsch. have complex physiological dormancy that can be released by 15 weeks stratification. The present study revealed that cold stratification enhanced content of H2O2, O2 -· and application of GA3 and ROS donors (Fenton reagent, H2O2, methylviologen and menadione) did not affect or only slightly promoted the germination of non-stratified, fully dormant seeds. Dormancy was markedly decreased by ROS-generating reagents, GA3 and fluridone (an inhibitor of ABA biosynthesis) and was enhanced by ROS-decreasing compounds (DMTU, Tiron, SB and DPI), diniconazole (Dinc, an inhibitor of ABA catabolism) and paclobutrazol (PAC, an inhibitor of GA biosynthesis) when dormancy was partially removed by cold stratification. The response to these compounds reduced with increasing time of stratification. ABA inhibited germination by repressing of NADPH oxidase activity and ROS accumulation and conversely, GA triggered germination by promoting an increase of NADPH oxidase activity and ROS levels. Data in this study, for the first time suggest releasing deep complex physiological dormancy by cold stratification is associated with interplay between ROS and ABA/GA.