In vitro tetraploidy induction creates enhancements in morphological, physiological and phytochemical characteristics in the fig tree (Ficus Carica L.)

Abstract

Fig tree (Ficus carica L.) is a precious fruit tree in semi-arid and arid areas worldwide which has difficulties in its conventional breeding programs. This study was carried out to make new genotypes with superior features based on the ploidy induction method. Thus, in vitro tetraploidization in two fig cultivars, namely 'Sabz' and 'Torsh', was successfully established using shoot tip explants and colchicine as the antimitotic agent in MS medium. The flow cytometry and chromosome counting techniques were used to verify tetraploid plants. The results revealed that, in comparison to the original diploid plants of both cultivars, tetraploid plants significantly had taller stems, larger leaves, a greater number of chloroplasts in guard cells, and higher chlorophyll content and photosynthesis rate. UPLC-MS analysis revealed that the level of growth stimulator phytohormones, including ZR, IAA, GA₃, SA, and JA in the tetraploid plants of both cultivars were significantly higher than their diploid controls. In contrast, they had less accumulated growth inhibitor phytohormone (ABA) than their diploid explant source. Moreover, tetraploid plants had significantly accumulated a higher content of phenolic compounds, total soluble sugars, and total soluble proteins, but showed a significantly less total antioxidant activity. Consequently, it is concluded that the growth advantages of tetraploid figs created in this study are substantial in terms of phytohormonal, physiological, and phytochemical superiorities, as compared to their corresponding diploid plants. Polyploidization proves as a promising breeding tool for future breeding programs of the fig tree.

Keywords: Chromosome doubling; Ficus carica; Flow cytometry; Growth advantages; Phytohormonal analysis.