Dataset Information

Experimental Evidence for Seed Metabolic Allometry in Barrel Medic (Medicago truncatula Gaertn.).

ABSTRACT: Seed size is often considered to be an important trait for seed quality, i.e., vigour and germination performance. It is believed that seed size reflects the quantity of reserve material and thus the C and N sources available for post-germinative processes. However, mechanisms linking seed size and quality are poorly documented. In particular, specific metabolic changes when seed size varies are not well-known. To gain insight into this aspect, we examined seed size and composition across different accessions of barrel medic (Medicago truncatula Gaertn.) from the genetic core collection. We conducted multi-elemental analyses and isotope measurements, as well as exact mass GC-MS metabolomics. There was a systematic increase in N content (+0.17% N mg^-1) and a decrease in H content (-0.14% H mg^-1) with seed size, reflecting lower lipid and higher S-poor protein quantity. There was also a decrease in ²H natural abundance (δ²H), due to the lower prevalence of ²H-enriched lipid hydrogen atoms that underwent isotopic exchange with water during seed development. Metabolomics showed that seed size correlates with free amino acid and hexoses content, and anticorrelates with amino acid degradation products, disaccharides, malic acid and free fatty acids. All accessions followed the same trend, with insignificant differences in metabolic properties between them. Our results show that there is no general, proportional increase in metabolite pools with seed size. Seed size appears to be determined by metabolic balance (between sugar and amino acid degradation vs. utilisation for storage), which is in turn likely determined by phloem source metabolite delivery during seed development.

SUBMITTER: Domergue JB

PROVIDER: S-EPMC9369157 | biostudies-literature | 2022 Jul

REPOSITORIES: biostudies-literature

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Experimental Evidence for Seed Metabolic Allometry in Barrel Medic (<i>Medicago truncatula</i> Gaertn.).

Domergue Jean-Baptiste JB Lalande Julie J Beucher Daniel D Satour Pascale P Abadie Cyril C Limami Anis M AM Tcherkez Guillaume G

International journal of molecular sciences 20220730 15

Seed size is often considered to be an important trait for seed quality, i.e., vigour and germination performance. It is believed that seed size reflects the quantity of reserve material and thus the C and N sources available for post-germinative processes. However, mechanisms linking seed size and quality are poorly documented. In particular, specific metabolic changes when seed size varies are not well-known. To gain insight into this aspect, we examined seed size and composition across differ ...[more]

PMID: 35955618

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Project description:BackgroundDNA methylation has a potential role in controlling gene expression and may, therefore, contribute to salinity adaptation in plants. Caliph medic (Medicago truncatula) is a model legume of moderate salinity tolerance capacity; however, a base-resolution DNA methylome map is not yet available for this plant.ResultsIn this report, a differential whole-genome bisulfite sequencing (WGBS) was carried out using DNA samples extracted from root tissues exposed to either control or saline conditions. Around 50 million differentially methylated sites (DMSs) were recognized, 7% of which were significantly (p < 0.05, FDR < 0.05) altered in response to salinity. This analysis showed that 77.0% of the contexts of DMSs were mCHH, while only 9.1% and 13.9% were mCHG and mCG, respectively. The average change in methylation level was increased in all sequence contexts, ranging from 3.8 to 10.2% due to salinity stress. However, collectively, the level of the DNA methylation in the gene body slightly decreased in response to salinity treatment. The global increase in DNA methylation due to salinity was confirmed by mass spectrometry analysis. Gene expression analysis using qPCR did not reveal a constant relationship between the level of mCG methylation and the transcription abundance of some genes of potential importance in salinity tolerance, such as the potassium channel KAT3, the vacuolar H+-pyrophosphatase (V-PPase), and the AP2/ERF and bZIP transcription factors, implying the involvement of other epigenetic gene expression controllers. Computational functional prediction of the annotated genes that embrace DMSs revealed the presence of enzymes with potential cellular functions in biological processes associated with salinity tolerance mechanisms.ConclusionsThe information obtained from this study illustrates the effect of salinity on DNA methylation and shows how plants can remodel the landscape of 5-methylcytosine nucleotide (5-mC) in the DNA across gene structures, in response to salinity. This remodeling varies between gene regions and between 5-mC sequence contexts. The mCG has a vague impact on the expression levels of a few selected potentially important genes in salt tolerant mechanisms.

Project description:In addition to being a forage crop, Caliph medic (Medicago truncatula) is also a model legume plant and is used for research focusing on the molecular characterization of the interaction between rhizobia and plants. However, the endophytic microbiome in this plant is poorly defined. Endophytic bacteria play a role in supplying plants with the basic requirements necessary for growth and development. Moreover, these bacteria also play a role in the mechanism of salinity stress adaptation in plants. As a prelude to the isolation and utilization of these bacteria in Caliph medic farming, 41 bacterial OTUs were identified in this project from within the interior of the roots of this plant by pyrosequencing of the small ribosomal subunit gene (16S rDNA) using a cultivation-independent approach. In addition, the differential abundance of these bacteria was studied following exposure of the plants to salinity stress. About 29,064 high-quality reads were obtained from the sequencing of six libraries prepared from control and salinity-treated tissues. Statistical analysis revealed that the abundance of ~70% of the OTUs was significantly (p ≤ 0.05) altered in roots that were exposed to salinity stress. Sequence analysis showed a similarity between some of the identified species and other, known, growth-promoting bacteria, marine and salt-stressed soil-borne bacteria, and nitrogen-fixing bacterial isolates. Determination of the amendments to the bacterial community due to salinity stress in Caliph medic provides a crucial step toward developing an understanding of the association of these endophytes, under salt stress conditions, in this model plant. To provide direct evidence regarding their growth promoting activity, a group of endophytic bacteria were isolated from inside of plant roots using a cultivation-dependent approach. Several of these isolates were able to produce ACC-deaminase, ammonia and IAA; and to solubilize Zn+2 and PO4-3. This data is consistent with the predicted occurrence (based on cultivation-independent techniques) of these bacteria and provides some insight into the importance of the endophytic bacteria in Caliph medic when grown under normal and saline conditions.

Dataset Information

Experimental Evidence for Seed Metabolic Allometry in Barrel Medic (Medicago truncatula Gaertn.).

Publications

Experimental Evidence for Seed Metabolic Allometry in Barrel Medic (<i>Medicago truncatula</i> Gaertn.).

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