Isoprothiolane advances improvement of color through gibberellic acid metabolism in satsuma mandarin (Citrus unshiu Marc.).

Abstract

Abstract The functions of isoprothiolane (IPT), which is a fungicide against rice blast, in carotenoid accumulation were examined in satsuma mandarin fruit (Citrus unshiu Marc). Whole trees were treated with IPT at 25 days before harvest. Concentrations of gibberellic acid-1 (GA1) and GA4 in the flavedo of IPT-treated trees were significantly decreased at 5 days after treatment (DAT) compared to the untreated control. The expressions of CitGA20ox1 in IPT-treated flavedo were lower than those in the untreated controls at 5 and 25 DAT. The CitGA3ox expressions in IPT-treated flavedo were lower than those in the untreated control at 5 DAT. ABA concentrations in IPT-treated flavedo were significantly higher than those in the untreated control at 25 DAT. The concentrations of b-cryptoxanthin in IPT-treated flavedo were higher than those in the untreated control at 25 DAT. The chlorophyll concentrations of IPT-treated flavedo were lower than those in the untreated control at 5 and 20 DAT. These results suggest that IPT advances b-cryptoxanthin accumulation through the regulation of endogenous GA1 and GA4 based on the inhibition of CitGA20ox1 and CitGA3ox expressions. It is possible that IPT can be utilized to improve coloration in other citrus fruit.