Abstract
Plant immunity is often negatively impacted by heat stress. However, the underlying molecular mechanisms remain poorly characterized. Based on a genome‐wide association mapping approach, this study aims to identify in Arabidopsis thaliana the genetic bases of robust resistance mechanisms to the devastating pathogen Ralstonia solanacearum under heat stress. A local mapping population was phenotyped against the R. solanacearum GMI1000 strain at 27 and 30 °C. To obtain a precise description of the genetic architecture underlying natural variation of quantitative disease resistance (QDR), we applied a genome‐wide local score analysis. Alongside an extensive genetic variation found in this local population at both temperatures, we observed a playful dynamics of quantitative trait loci along the infection stages. In addition, a complex genetic network of interacting loci could be detected at 30 °C. As a first step to investigate the underlying molecular mechanisms, the atypical meiotic cyclin SOLO DANCERS gene was validated by a reverse genetic approach as involved in QDR to R. solanacearum at 30 °C. In the context of climate change, the complex genetic architecture underlying QDR under heat stress in a local mapping population revealed candidate genes with diverse molecular functions.
Highlights
Climate scenarios predict that extreme climate events will become more frequent by the end of the century (IPCC, 2018), alongside an expected increase in global surface temperature from 1.5 to 4.8°C (IPCC, 2018)
A genome-wide association study (GWAS) performed in A. thaliana and aimed at exploring the genetic bases associated with the natural variation of plant response to strain GMI1000 at 30°C led to the identification of the Strictosidine Synthase-Like protein 4 (SSL4) gene, the underlying molecular mechanisms are still unknown (Aoun et al, 2017)
Using a reverse genetic approach, we identified SOLO DANCERS (SDS) encoding a cyclin-like protein as the gene underlying one of the two additive QTLs detected at 30 °C
Summary
Climate scenarios predict that extreme climate events will become more frequent by the end of the century (IPCC, 2018), alongside an expected increase in global surface temperature from 1.5 to 4.8°C (IPCC, 2018). A genome-wide association study (GWAS) performed in A. thaliana and aimed at exploring the genetic bases associated with the natural variation of plant response to strain GMI1000 at 30°C led to the identification of the Strictosidine Synthase-Like protein 4 (SSL4) gene, the underlying molecular mechanisms are still unknown (Aoun et al, 2017). We investigated the genetic bases of QDR to R. solanacearum under elevated temperature by performing a GWAS at a small geographical scale using the TOU-A local mapping population This local mapping population offers several advantages, including (a) the detection of more than 1.9 million single nucleotide polymorphims (SNPs), only 5.6 times less than observed in a panel of 1,135 accessions collected at the worldwide scale (Frachon et al, 2017); (b) an extensive genetic variation for a large range of phenotypic traits, including QDR to the bacterial vascular pathogen Xanthomonas campestris pv. We focused on the additive QTL with the highest allelic
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