Genome-wide expression and variation in nucleotide sequences lead to differential response of Arabidopsis thaliana ecotypes towards arsenic stress under sulfur limiting condition

Abiotic stresses such as heavy metals and nutrient imbalance constitute a significant threat to plant productivity. Among the known heavy metals, arsenic (As) toxicity widely affects plants and animals. In the recent past, various approaches have been used to study and ameliorate As accumulation in the plants. Of the different approaches, the detoxification mechanism utilizes various sulfur-related compounds; therefore, the limitation of sulfur leads to enhanced toxicity in plants. Though studies have suggested links between As and sulfur responses, a deeper understanding of the molecular mechanisms of these responses is required. In this study, transcriptome analysis of the Arabidopsis accessions (Koz2–2 and Ri-0) with contrasting responses to sulfate limitation and As stress was carried out to identify genes involved in regulating various processes. Several genes associated with growth and development, stress, or sulfate metabolism and secondary plant product biosynthesis were found to be differentially expressed in contrasting accessions under sulfate limitation and As stress. A set of genes, including DREB1A and Marneral Synthase 1(MRN1), were exclusively upregulated under the combined stress in Koz2–2. Further, transcriptome analysis also revealed higher nucleotide variation in Koz2–2 than in Ri-0, which could be a reason for the contrasting response under the different stresses among these accessions. Interestingly, LCR44 (Low molecular weight Cysteine Rich 44), a putative defensin-like protein 73, was found to be uniquely upregulated in Koz2–2. The sequence analysis of LCR44 through transcriptome datasets suggested intron retention and insertion of nucleotides in Koz2–2. Hence, this study enriches the knowledge of genetic components to cope with sulfate assimilation and As stress in plants.