ABA crosstalk with auxin and ethylene in biosynthesis and degradation of inulin‐type fructans

The effect of different hormones on fructan accumulation and the regulation of biosynthesis and degradation genes has been confirmed; however, information of hormonal interaction mechanisms on fructan content and mean degree of polymerization (mDP) is limited. Cell suspension cultures of chicory were prepared and treated using abscisic acid (ABA), auxin (AUX), Ethylene (ETH), ABA+AUX, and ABA+ETH, then inulin concentration, mDP of inulin and expression of FAZY genes were determined. Low concentration of AUX and ETH increased fructan content and high concentration of AUX and ETH decreased it. Exogenous ABA increased mDP of inulin and it coincided with the low expression of 1-FEHII. In hormonal interaction, ABA changed and adjusted the effect of both AUX and ETH. ABA with a low level of both hormones resulted in a decrease in inulin content and increasing mDP and it coincided with low expression of FEHII. ABA with a high level of both hormones caused increasing in inulin content with lower mDP and it coincided with high expression of biosynthesis (1-FFT) and degradation (1-FEHII) genes. The effect of both AUX and ETH was almost the same although the effect of ETH was more severe. ABA had a modular role in both combinations with AUX and ETH. Among biosynthesis and degradation genes, the expression of 1-FEHII was more affected by hormones.