Exogenous putrescine activates the arginine-polyamine pathway and inhibits the decomposition of endogenous polyamine in Anthurium andraeanum under chilling stress

Abstract

Chilling temperature is an important abiotic stress that affects the product quality of Anthurium andraeanum. Exogenous putrescine (Put) can reduce the physiological damage caused by chilling stress on anthurium seedlings, and induce the synthesis of endogenous arginine (Arg). In this study, anthurium seedlings were pretreated with Put, Put+D-arginine (D-Arg), Put+difluoromethylornithine (DFMO), and Put+D-Arg+DFMO solutions for four weeks. Subsequently, the seedlings were subjected to chilling stress at 6 ºC for three days, followed by a recovery at 25 ºC for one day. The contents of endogenous Arg and polyamines (PAs), as well as the activities of arginine decarboxylase (ADC), ornithine decarboxylase (ODC), diamine oxidase (DAO), and polyamine oxidase (PAO) in the roots and leaves of each treatment group were measured during the experiments. The results were further confirmed on the transcriptional level via transcriptome sequencing and qRT-PCR. We found that the supplementation of Put promoted the synthesis of endogenous Arg and its conversion to PAs, and reduced the decomposition rate of endogenous PAs under chilling stress. ADC was the main enzyme that promoted the synthesis of endogenous Put. The supplementation of D-Arg or/and DFMO inhibited the synthesis of endogenous Arg and its conversion to Put, and accelerated the decomposition rate of endogenous PAs. The qRT-PCR confirmed four DEGs related to ADC, amino-acid acetyltransferase NAGS1 and polyamine biosynthetic process identified from the sequencing results. In summary, the supplementation of Put activated the arginine-polyamine pathway in anthurium under chilling stress, increased the activity of ADC and the expression of related genes, and moderately inhibited the decomposition of endogenous PAs. The supplementation of D-Arg or/and DFMO exhibited the opposite effects, which confirmed the effects of Put.