The Seed Repair Response during Germination: Disclosing Correlations between DNA Repair, Antioxidant Response, and Chromatin Remodeling in Medicago truncatula

• Published in: Frontiers in plant science 2017-11, Vol.8, p.1972-1972
• Main Authors: Pagano, Andrea, Araújo, Susana de Sousa, Macovei, Anca, Leonetti, Paola, Balestrazzi, Alma
• Format: Article
• Language: English
• Subjects: antioxidant response; chromatin remodeling; comet assay; DNA repair; Medicago truncatula; Plant Science; seed germination
• ISSN: 1664-462X; 1664-462X
• DOI: 10.3389/fpls.2017.01972

This work provides novel insights into the effects caused by the histone deacetylase inhibitor trichostatin A (TSA) during seed germination, with emphasis on the seed repair response. Seeds treated with H O and TSA (10 and 20 μM) were collected during imbibition (8 h) and at the radicle protrusion phase. Biometric data showed delayed germination and impaired seedling growth in TSA-treated samples. Comet assay, performed on radicles at the protrusion phase and 4-days old seedlings, revealed accumulation of DNA strand breaks upon exposure to TSA. Activation of DNA repair toward TSA-mediated genotoxic damage was evidenced by the up-regulation of ( ) gene involved in the removal of oxidative DNA lesions, ( ) gene, a key determinant of seed quality, required for the rejoining of DNA double strand breaks and genes encoding the multipurpose DNA repair enzymes tyrosyl-DNA phosphodiesterases. Since radical scavenging can prevent DNA damage, the specific antioxidant activity (SAA) was measured by DPPH (1,1-diphenyl-2-picrylhydrazyl) and Folin-Ciocalteu reagent assays. Fluctuations of SAA were observed in TSA-treated seeds/seedlings concomitant with the up-regulation of antioxidant genes ( ) and ( ). Chromatin remodeling, required to facilitate the access of DNA repair enzymes at the damaged sites, is also part of the multifaceted seed repair response. To address this aspect, still poorly explored in plants, the ( ) gene was analyzed. TRRAP is a transcriptional adaptor, so far characterized only in human cells where it is needed for the recruitment of histone acetyltransferase complexes to chromatin during DNA repair. The gene and the predicted interacting partners ( ) and ( ) showed tissue- and dose-dependent fluctuations in transcript levels. PCA (Principal Component Analysis) and correlation analyses suggest for a new putative link between DNA repair and chromatin remodeling that involves and genes, in the context of seed germination. Interesting correlations also connect DNA repair and chromatin remodeling with antioxidant players and proliferation markers.