The seed repair response during germination: Disclosing correlations between DNA repair, antioxidant response, and chromatin remodeling in medicago truncatula

Andrea Pagano, Susana De Sousa Araújo, Anca Macovei, Paola Leonetti, Alma Balestrazzi

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

This work provides novel insights into the effects caused by the histone deacetylase inhibitor trichostatin A (TSA) during Medicago truncatula seed germination, with emphasis on the seed repair response. Seeds treated with H2O and TSA (10 and 20μM) 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 M. truncatula 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 MtOGG1(8-OXOGUANINE GLYCOSYLASE/LYASE) gene involved in the removal of oxidative DNA lesions, MtLIGIV(LIGASE IV) gene, a key determinant of seed quality, required for the rejoining of DNA double strand breaks and TDP(TYROSYL-DNA PHOSPHODIESTERASE) 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 MtSOD(SUPEROXIDE DISMUTASE, MtAPX(ASCORBATE PEROXIDASE) and MtMT2(TYPE 2 METALLOTHIONEIN). 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 MtTRRAP(TRANSFORMATION/TRANSACTIVATION DOMAIN-ASSOCIATED PROTEIN) 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 MtTRRAP gene and the predicted interacting partnersMtHAM2 (HISTONE ACETYLTRANSFERASE OF THEMYST FAMILY) and MtADA2A (TRANSCRIPTIONAL ADAPTOR) showed tissue- and dose-dependent fluctuations in transcript levels. PCA (Principal Component Analysis) and correlationanalyses suggest for a new putative link between DNA repair and chromatin remodeling that involves MtOGG1 and MtTRRAP genes, in the context of seed germination. Interesting correlations also connect DNA repair and chromatin remodeling with antioxidant players and proliferation markers.

Original languageEnglish
Article number1972
JournalFrontiers in Plant Science
Volume8
DOIs
Publication statusPublished - 14 Nov 2017

Keywords

  • Antioxidant response
  • Chromatin remodeling
  • Comet assay
  • DNA repair
  • Medicago truncatula
  • Seed germination
  • Trichostatin A

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