Effects of temperature pretreatments and carbohydrate type on androgenesis induction in anther culture of Capparis spinosa L.

Caper (Capparis spinosa L.) is a rich source of rutin, plays an essential role in human health. In the present study, the effects of cold (25°C as control, 4°C, and 7°C for 2, 4, and 7 days), heat (25°C as control, 30°C for 14 days, 32°C for 2 and 4 days, and 35°C for 8 hours), and carbohydrate treatments on the androgenesis efficiency were studied in the anther culture of caper. Also, the effects of maltose and sucrose at the concentrations of 30 and 60 g L-1 in combination with two temperature treatments (1- 30°C for 14 days and 2- 7°C for 7 days + azacytidine and 2,4-D pretreatments) on the androgenesis induction was evaluated. The temperature and carbohydrate treatments showed statistically significant differences (p ≤0.01) in terms of callus and embryo formation. The 7°C for 2, 4, and 7 days produced the highest percentage (at the third week: 80, 78.34, and 76.67%, respectively) and callogenesis speed (7.85, 7.75, and 7.60 calli week-1, respectively) and the 7°C for 7 days produced the highest embryo production (0.57 embryo anther-1). The 30°C for 14 days treatment showed the highest percentage (at the third week: 100%) and callogenesis speed (9.44 calli week-1). While the 32°C for 2 and 3 days and also 30°C for 14 days produced the highest number of embryos per anther (0.22, 0.20, and 0.18 embryo, respectively). The use of 30 g L-1 maltose in combination with the 30°C for 14 days produced the highest percentage (at the third week: 91.66%) and callogenesis speed (8.94 calli week-1), while the 30 g L-1 maltose in combination with the 7°C for 7 days + azacytidine and 2,4-D pretreatments produced the highest mean embryo number per anther (0.55 embryo). The results of this research are of great importance for the use in the caper breeding programs.