Combined genomics to discover genes associated with tolerance to soil carbonate

Abstract

Carbonate-rich soils limit plant performance and crop production. Previously, local adaptation to carbonated soils was detected in wild Arabidopsis thaliana accessions, allowing the selection of two demes with contrasting phenotypes: A1 (carbonate tolerant, c+) and T6 (carbonate sensitive, c−). Here, A1(c+) and T6(c−) seedlings were grown hydroponically under control (pH 5.9) and bicarbonate conditions (10 mM NaHCO3, pH 8.3) to obtain ionomic profiles and conduct transcriptomic analysis. In parallel, A1(c+) and T6(c−) parental lines and their progeny were cultivated on carbonated soil to evaluate fitness and segregation patterns. To understand the genetic architecture beyond the contrasted phenotypes, a bulk segregant analysis sequencing (BSA-Seq) was performed. Transcriptomics revealed 208 root and 2503 leaf differentially expressed genes in A1(c+) versus T6(c−) comparison under bicarbonate stress, mainly involved in iron, nitrogen and carbon metabolism, hormones and glycosylates biosynthesis. Based on A1(c+) and T6(c−) genome contrasts and BSA-Seq analysis, 69 genes were associated with carbonate tolerance. Comparative analysis of genomics and transcriptomics discovered a final set of 18 genes involved in bicarbonate stress responses that may have relevant roles in soil carbonate tolerance.