Autotetraploid synthetic seeds of Ficus carica L. exhibit a superior cold acclimation system than their origin diploids

Abstract

Abstract The current study investigates cold conservation of Synseeds of two fig cytotypes using sodium alginate 3% and nodal segments as explants. The biometrical and some important physiochemical parameters were evaluated to determine the cold acclimation responses of both cytotypes’ Synseeds. Results demonstrated that in the 9th month of conservation, 37.5% of autotetraploid Synseeds had survived, whereas all diploid Synseeds had died. The survival rate of autotetraploid Synseeds (87.5%) in the 6th month of conservation was significantly higher than that of their origin diploids (54.16%). Autotetraploid Synseeds produced significantly lower amounts of stress indexes such as H2O2 and MDA (53.7% and 31.7%, respectively) during the cold conservation period, particularly in the 6th month of conservation, than their origin diploids; which were accompanied by a lower ion leakage (49.75%) and a higher water content (8.34%) compared to their origin diploids. Furthermore, autotetraploid Synseeds exhibited superior capability of accumulating cell osmolytes in the 6th month of conservation than their origin diploids, including higher contents up to 34.62% TSS, 73.78% proline, and 43.96% glycine betaine. The activity of two key antioxidant enzymes of CAT and APX was also significantly higher in autotetraploid Synseeds up to 48.14% and 30.29% in the 6th month of conservation, respectively, than in their origin diploids. According to the findings, it could be concluded that the autotetraploid cytotype has significantly more tolerance to cold stress due to its superior cold acclimation strategies, mainly including the osmolytes accumulation and cell detoxification dependent on antioxidant enzymes, than their origin diploid cytotype.