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

Yang Yang,Ye Ye,Guo Guo,Wang Wang,Wu Wu,Zhou Zhou,Chen Chen

doi:10.3390/ijms20133129

Yang Yang, Ye Ye + Show 5 more

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https://doi.org/10.3390/ijms20133129

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Abstract

Magnesium (Mg) deficiency is one of the major constraining factors that limit the yield and quality of agricultural products. Uniform seedlings of the Citrus sinensis 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 C. sinensis 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 C. sinensis 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 C. sinensis 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 C. sinensis and enrich our understanding of the molecular mechanisms by which plants adapted to a Mg deficient condition.

Highlights

Magnesium (Mg) is an essential macronutrient for plant growth and production
Whether the lack of Mg-ATP caused by the depletion of Mg or the accumulation of cargo such as sucrose in C. sinensis leaves is the main reason for the up-regulation of the kinesin genes remains further investigation
We successfully identified and quantified 194 Differentially Expressed Genes (DEGs) related to lipid metabolism in C. sinensis leaves, of which, 86 DEGs were upregulated and 108 DEGs were downregulated by Mg deficiency (Table S8)

Summary

Introduction

Magnesium (Mg) is an essential macronutrient for plant growth and production. As the eighth most abundant element in the Earth’s crust, soil Mg originates from weathering of minerals containing Mg, such as serpentine, bishopvillite, calcite, dolomite, magnesite, periclase, talcum and diopside. Due to the key role of Mg in phloem loading of sucrose and photosynthate partitioning between source and sink organs under Mg deficiency [11,12], the dysfunction of photosynthate transport led to the accumulation of carbon in resource leaves before the appearance of chlorosis and necrosis, and resupply of Mg rapidly enhanced the sucrose export through phloem from resource leaves [13]. Such quick recovery of the sucrose export regardless of light condition indicated that enhancement of sucrose export after Mg resupply is only related to Mg availability [3]. This suggested that trans-membrane transportation carrier or channel-dependent phloem-loading of sucrose was prompted by Mg-ATP complex and Mg deficiency led to decreased H+-ATPase activity and a reduced proton gradient which energizes active phloem loading

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