Magnesium Deficiency Induced Global Transcriptome Change in Citrus sinensis Leaves Revealed by RNA-Seq

Abstract

Magnesium (Mg) deficiency is one of the major constraining factors that limit the yield and quality of agricultural products. Uniform seedlings of the <i>Citrus sinensis</i> were irrigated with Mg deficient (0 mM MgSO₄) and Mg sufficient (1 mM MgSO₄) nutrient solutions for 16 weeks. CO₂ assimilation, starch, soluble carbohydrates, TBARS content and H₂O₂ production were measured. Transcriptomic analysis of <i>C. sinensis</i> leaves was performed by Illumina sequencing. Our results showed that Mg deficiency decreased CO₂ assimilation, but increased starch, sucrose, TBARS content and H₂O₂ production in <i>C. sinensis</i> leaves. A total of 4864 genes showed differential expression in response to Mg deficiency revealed by RNA-Seq and the transcriptomic data were further validated by real-time quantitative PCR (RT-qPCR). Gene ontology (GO) enrichment analysis indicated that the mechanisms underlying Mg deficiency tolerance in <i>C. sinensis</i> may be attributed to the following aspects: a) enhanced microtubule-based movement and cell cycle regulation; b) elevated signal transduction in response to biotic and abiotic stimuli; c) alteration of biological processes by tightly controlling phosphorylation especially protein phosphorylation; d) down-regulation of light harvesting and photosynthesis due to the accumulation of carbohydrates; e) up-regulation of cell wall remodeling and antioxidant system. Our results provide a comprehensive insight into the transcriptomic profile of key components involved in the Mg deficiency tolerance in <i>C. sinensis</i> and enrich our understanding of the molecular mechanisms by which plants adapted to a Mg deficient condition.