Metabolic and gene expression hallmarks of seed germination uncovered by sodium butyrate in Medicago truncatula

Abstract

Because high-quality seeds are essential for successful crop production in challenging environments, understanding the molecular bases of seed vigour will lead to advances in seed technology. Histone deacetylase inhibitors, promoting histone hyperacetylation, are used as tools to explore aspects still uncovered of the abiotic stress response in plants. The aim of this work was to investigate novel signatures of seed germination in Medicago truncatula, using the histone deacetylase inhibitor sodium butyrate (NaB) as stress agent. NaB-treated and untreated seeds collected at 2 and 8 hr of imbibition and at the radicle protrusion stage underwent molecular phenotyping and nontargeted metabolome profiling. Quantitative enrichment analysis revealed the influence of NaB on seed nucleotide, amino acid, lipid, and carbohydrate metabolism. Up-regulation of antioxidant and polyamine biosynthesis genes occurred in response to NaB. DNA damage evidenced in NaB-treated seeds correlated with up-regulation of base-excision repair genes. Changes in N -methyladenosine and N -methylguanine were associated with up-regulation of MtALKBH1 (alkylation repair homolog) gene. N ,N -dimethylguanosine and 5-methylcytidine, tRNA modifications involved in the post-transcriptional regulation of DNA damage response, were also accumulated in NaB-treated seeds at the radicle protrusion stage. The observed changes in seed metabolism can provide novel potential metabolic hallmarks of germination.

Hydropriming and Biopriming Improve Medicago truncatula Seed Germination and Upregulate DNA Repair and Antioxidant Genes

“…These had been previously reported to be upregulated during seed imbibition under physiological conditions or in the presence of osmotic stress (polyethylene glycol, PEG) in M. truncatula; their expression was mostly induced after 8 h of imbibition with water and 12 h of imbibition in the presence of PEG [29]. Other treatments with histone deacetylase inhibitors, for example trichostatin A (TSA) and sodium butyrate (NaB), have confirmed the enhanced expression of these genes during the first stages of seed germination [6,7]. Here, we show the upregulation of OGG1 and FPG genes in response both hydropriming and biopriming (Figure 4b,c).…”

“…The next step was to examine the expression patterns of genes that play roles in DNA repair and antioxidant defense, previously used as indicators of seed quality during the early stages of germination (namely seed imbibition) [5][6][7][8]. This is a rather important aspect because such molecular indicators allow the prediction of seed quality in a very short time, thus providing assistance to Seed Companies to design customized priming protocols [2,3,9,10].…”

“…In our previous works, we reported that genes playing roles in DNA repair and antioxidant responses can be used as indicators of seed quality and seeding growth [5][6][7][8]. Here we focused on the expression patters of OGG1 (8-Oxoguanine DNA glycosylase) and FPG (Formamidopyrimidine-DNA glycosylase), involved in Base Excision Repair (BER), APX (Ascorbate peroxidase) and SOD (Superoxide dismutase), encoding known ROS scavengers, and MT2 (Metallothionein type 2), proven to act both as ROS scavenger and repair enzyme [41].…”

“…This is characterized by rapid water uptake, which in turn activates a series of dynamic biochemical events such as the use of reserve storage compounds (lipids, carbohydrates, proteins), production of reactive oxygen species (ROS) and subsequent activation of antioxidant enzymes, DNA damage sensing and repair [3]. Indeed, intense DNA repair, essential for de novo DNA synthesis in embryo cells [4], and enhanced antioxidant functions are the prerequisites of a successful germination process and can be used as molecular markers of seed vigour [5][6][7][8][9].…”

“…The efficacy on the treatments was evaluated based on phenotypic (germination parameters and seedling biometric measurements) and molecular (expression profiles of genes involved in DNA repair and antioxidant response) aspects. Investigating the expression profiles of genes that can be used as indicators of seed quality and seeding growth [5][6][7][8] is intended to speed up the selection of high-quality seed lots. For instance, OGG1 (8-Oxoguanine glycosylase) and FPG (Formamidopyrimidine-DNA glycosylase) genes, playing similar roles within the BER (Base Excision Repair) pathway, were previously shown to be upregulated during seed imbibition in M. truncatula [29].…”