Genome-Wide Transcriptional Changes and Lipid Profile Modifications Induced by Medicago truncatula N5 Overexpression at an Early Stage of the Symbiotic Interaction with Sinorhizobium meliloti.

Chiara Santi,Nicola Vitulo,Barbara Molesini,Tiziana Pandolfini,Flavia Guzzo,Youry Pii

doi:10.3390/genes8120396

Chiara Santi, Nicola Vitulo + Show 4 more

Open Access

https://doi.org/10.3390/genes8120396

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Journal: Genes	Publication Date: Dec 19, 2017
Citations: 11	License type: CC BY 4.0

Affiliation: University of Verona, Free University of Bozen-Bolzano

Abstract

Plant lipid-transfer proteins (LTPs) are small basic secreted proteins, which are characterized by lipid-binding capacity and are putatively involved in lipid trafficking. LTPs play a role in several biological processes, including the root nodule symbiosis. In this regard, the Medicago truncatula nodulin 5 (MtN5) LTP has been proved to positively regulate the nodulation capacity, controlling rhizobial infection and nodule primordia invasion. To better define the lipid transfer protein MtN5 function during the symbiosis, we produced MtN5-downregulated and -overexpressing plants, and we analysed the transcriptomic changes occurring in the roots at an early stage of Sinorhizobium meliloti infection. We also carried out the lipid profile analysis of wild type (WT) and MtN5-overexpressing roots after rhizobia infection. The downregulation of MtN5 increased the root hair curling, an early event of rhizobia infection, and concomitantly induced changes in the expression of defence-related genes. On the other hand, MtN5 overexpression favoured the invasion of the nodules by rhizobia and determined in the roots the modulation of genes that are involved in lipid transport and metabolism as well as an increased content of lipids, especially galactolipids that characterize the symbiosome membranes. Our findings suggest the potential participation of LTPs in the synthesis and rearrangement of membranes occurring during the formation of the infection threads and the symbiosome membrane.

Highlights

Plant lipid transfer proteins (LTPs) constitute a large family of small proteins (6.5–10.5 kDa), with an isoelectric point commonly ranging from 8.5 to 12, characterized by the capacity to bind and transport hydrophobic molecules [1,2,3]
On the basis of these analyses, we identified the principal pathways that are associated with Medicago truncatula nodulin 5 (MtN5) function, and revealed that MtN5 participates in the lipid remodelling induced by rhizobia infection
Regarding the genes playing a role in rhizobia symbiosis (Figure 3A and Supplementary Table S1), we found two transcripts coding for nodule-specific cysteine-rich (NCR) secreted peptides (Medtr4g065390, Medtr3g027180), which were upregulated in MtN5hp inoculated roots in comparison to wild type (WT) ones with a fold change of 23 and

Summary

Introduction

Plant lipid transfer proteins (LTPs) constitute a large family of small proteins (6.5–10.5 kDa), with an isoelectric point commonly ranging from 8.5 to 12, characterized by the capacity to bind and transport hydrophobic molecules [1,2,3]. Plant LTPs are often reported as non-specific LTPs (nsLTPs), because of their capacity to associate with various phospholipids with broad specificity [4]. Members of the nsLTP family are regulated by drought, temperature, wounding, as well as phytohormones, such as abscisic acid and methyl jasmonate [6]. These features are indicative of a great variety of biological functions that are played in plants [7,8,9]. Various biological roles have been proposed for plant LTPs, including defence against

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Conclusion