An Integrative Transcriptomic and Metabolomic Analysis of Red Pitaya (Hylocereus polyrhizus) Seedlings in Response to Heat Stress.

Mei Zhang,Kuaifei Xia,Hongfang Lu,Shuguang Jian,Quandong Nong,Zhengli Jiao,Mingyong Zhang,Weijuan Xu,Jiantong Chen

doi:10.3390/genes12111714

Abstract

Red pitaya (Hylocereus polyrhizus) is a significant functional food that is largely planted in Southeast Asia. Heat stress (HS) induced by high temperatures is likely to restrict the growth and survival of red pitaya. Although pitaya can tolerate temperatures as high as 40 °C, little is known of how it can withstand HS. In this study, the transcriptomic and metabolomic responses of red pitaya seedlings to HS were analyzed. A total of 198 transcripts (122 upregulated and 76 downregulated) were significantly differentially expressed after 24 h and 72 h of exposure to 42 °C compared with a control grown at 28 °C. We also identified 64 differentially accumulated metabolites in pitaya under HS (37 increased and 27 decreased). These differential metabolites, especially amino acids, organic acids, and sugars, are involved in metabolic pathways and the biosynthesis of amino acids. Interaction network analysis of the heat-responsive genes and metabolites suggested that similar pathways and complex response mechanisms are involved in the response of pitaya to HS. Overexpression of one of the upregulated genes (contig10820) in Arabidopsis, which is a homolog of PR-1 and named HuPR-1, significantly increased tolerance to HS. This is the first study showing that HuPR-1 plays a role in the response of pitaya to abiotic stress. These findings provide valuable insights that will aid future studies examining adaptation to HS in pitaya.

Highlights

Global ambient temperature has gradually increased because of greenhouse gases such as CO2, methane, chlorofluorocarbons, and nitrous oxides
Nine transcriptome libraries were constructed using Poly-A+ RNA isolated from three-month-old red pitaya seedlings showing normal growth under control conditions (28 ◦C) or heat treatment (42 ◦C)
Previous studies have shown that Heat stress (HS) signals are transduced through multiple signaling pathways to activate Transcription factors (TFs), which induces the expression of many heat shock proteins (HSPs) and other HS-responsive genes to respond to HS

Summary

Introduction

Global ambient temperature has gradually increased because of greenhouse gases such as CO2, methane, chlorofluorocarbons, and nitrous oxides. Heat stress (HS) is usually defined as a temperature increase above a threshold level for a period of time sufficient to cause irreversible damage to plant growth and development. It occurs in response to a transient increase in temperature, usually 10–15 ◦C above environmental temperature. HS associated with increases in ambient temperature globally poses a serious threat to the growth and production of plants. Plants have evolved various physiological and biochemical adaptations to avoid or reduce the damage caused by HS [1]. HS is one of the most crucial forms of abiotic stress, as it disrupts homeostasis, limits plant growth and development, and even leads to death [2,3]. Elucidating the mechanisms by which plants respond to HS is critically important

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Conclusion