RNA Sequencing Reveals That Both Abiotic and Biotic Stress-Responsive Genes are Induced during Expression of Steroidal Glycoalkaloid in Potato Tuber Subjected to Light Exposure.

Zhang Zhang,Qin Qin,Chen Chen,Kang Kang,Zuo Zuo

doi:10.3390/genes10110920

Abstract

Steroidal glycoalkaloids (SGAs), which are widely produced by potato, even in other Solanaceae plants, are a class of potentially toxic compounds, but are beneficial to host resistance. However, changes of the other metabolic process along with SGA accumulation are still poorly understood and researched. Based on RNA sequencing (RNA-seq) and bioinformatics analysis, the global gene expression profiles of potato variety Helan 15 (Favorita) was investigated at four-time points during light exposure. The data was further verified by using quantitative Real-time PCR (qRT-PCR). When compared to the control group, 1288, 1592, 1737, and 1870 differentially expressed genes (DEGs) were detected at 6 h, 24 h, 48 h, and 8 d, respectively. The results of both RNAseq and qRT-PCR showed that SGA biosynthetic genes were up-regulated in the potato tuber under light exposure. Functional enrichment analysis revealed that genes related to PS light reaction and Protein degradation were significantly enriched in most time points of light exposure. Additionally, enriched Bins included Receptor kinases, Secondary metabolic process in flavonoids, Abiotic stress, and Biotic stress in the early stage of light exposure, but PS Calvin cycle, RNA regulation of transcription, and UDP glucosyl and glucoronyl transferases in the later stage. Most of the DEGs involved in PS light reaction and Abiotic stress were up-regulated at all four time points, whereas DEGs that participated in biotic stresses were mainly up-regulated at the later stage (48 h and 8 d). Cis-element prediction and co-expression assay were used to confirm the expressional correlation between genes that are responsible for SGA biosynthesis and disease resistance. In conclusion, the expressions of genes involved in PS light reaction, Abiotic stress, and Biotic stress were obviously aroused during the accumulation of SGAs induced by light exposure. Moreover, an increased defense response might contribute to the potato resistance to the infection by phytopathogenic microorganisms.

Highlights

Potato (Solanum tuberosum L.) is one of the most important staple crops for direct and processed consumption in many countries around the world
Cis-element prediction and co-expression assay were used to confirm the expressional correlation between genes that are responsible for steroidal glycoalkaloids (SGAs) biosynthesis and disease resistance
Co-expression networks of genes that are responsible for SGA biosynthesis and disease resistance were constructed with Weighted Gene Co-Expression Network Analysis (WGCNA) [32]

Summary

Introduction

Potato (Solanum tuberosum L.) is one of the most important staple crops for direct and processed consumption in many countries around the world. Genes 2019, 10, 920 when the level of total SGA is up to 200 mg kg−1 fresh weight of unpeeled raw potato tuber [3]. It can induce mild symptoms of glycoalkaloid toxicity, including headache, nausea, and diarrhea, but more severe and even fatal poisonings have been reported [4]. Previous reports found that SGAs were not responsible for the resistance to late blight of hybrids [6,7] These investigations are only limited to the relationship between SGA content and potato resistance; an increased understanding of the relationship of SGA biosynthetic pathway and potato molecular defense responses is of broad interest

Results

Discussion

Conclusion