Transcript and metabolite changes during the early phase of abscisic acid-mediated induction of crassulacean acid metabolism in Talinum triangulare

J Exp Bot. 2019 Nov 29;70(22):6581-6596. doi: 10.1093/jxb/erz189.

Abstract

Crassulacean acid metabolism (CAM) has evolved as a water-saving strategy, and its engineering into crops offers an opportunity to improve their water use efficiency. This requires a comprehensive understanding of the regulation of the CAM pathway. Here, we use the facultative CAM species Talinum triangulare as a model in which CAM can be induced rapidly by exogenous abscisic acid. RNA sequencing and metabolite measurements were employed to analyse the changes underlying CAM induction and identify potential CAM regulators. Non-negative matrix factorization followed by k-means clustering identified an early CAM-specific cluster and a late one, which was specific for the early light phase. Enrichment analysis revealed abscisic acid metabolism, WRKY-regulated transcription, sugar and nutrient transport, and protein degradation in these clusters. Activation of the CAM pathway was supported by up-regulation of phosphoenolpyruvate carboxylase, cytosolic and chloroplastic malic enzymes, and several transport proteins, as well as by increased end-of-night titratable acidity and malate accumulation. The transcription factors HSFA2, NF-YA9, and JMJ27 were identified as candidate regulators of CAM induction. With this study we promote the model species T. triangulare, in which CAM can be induced in a controlled way, enabling further deciphering of CAM regulation.

Keywords: Talinum triangulare; Abscisic acid; crassulacean acid metabolism; metabolome; time course; transcriptome.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abscisic Acid / metabolism*
  • Abscisic Acid / pharmacology
  • Carbohydrate Metabolism / drug effects
  • Carbohydrate Metabolism / genetics
  • Carboxylic Acids / metabolism*
  • Cluster Analysis
  • Gene Expression Regulation, Plant / drug effects
  • Genes, Plant
  • Metabolome / genetics*
  • Portulacaceae / drug effects
  • Portulacaceae / genetics*
  • Portulacaceae / metabolism*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Signal Transduction / drug effects
  • Transcriptome / genetics

Substances

  • Carboxylic Acids
  • RNA, Messenger
  • Abscisic Acid