IAA regulated levels of endogenous phytohormones in relation to chilling tolerance in cold-stored peaches after harvest.

The effects of indoleacetic acid (IAA) treatment on chilling injury and endogenous phytohormones in peach fruit were studied. The results showed that IAA treatment decreased chilling injury index of cold-stored peaches, effectively maintaining fruit firmness and reducing the electrical conductivity level. IAA treatment upregulated the expression of IAA biosynthetic gene PpMES and signaling pathway gene PpSAUR , but reduced the transcript abundance of IAA degradative genes PpDAO , PpGH3 , and PpIAMT , leading to endogenous IAA accumulation in treated peaches. Meanwhile, after IAA treatment, contents of melatonin and γ-aminobutyric acid (GABA) were also increased which was associated with the upregulation of their anabolic genes and downregulation in GABA catabolic genes. In addition, the levels of abscisic acid (ABA) and gibberellin (GA) were reduced in treated peaches due to its modification in the transcript levels of ABA and GA metabolic genes. Collectively, IAA could alleviate the symptoms of chilling injury in peach fruit via regulating contents of endogenous phytohomones such as IAA, melatonin, GABA and GA. • IAA treatment reduced chilling injury and maintain fruit quality in peaches. • IAA induced endogenous IAA content in harvested peaches. • IAA increased melatonin and GABA contents in harvested peaches. • IAA inhibited ABA and GA contents in harvested peaches. [ABSTRACT FROM AUTHOR]