Alleviating effect of calcium sulfate on aluminum stress through enhanced malate release with increased gene expression of malate transporter and sulfate transporter

Abstract

ABSTRACT Gypsum (calcium sulfate) are commonly used to improve subsoil acidity. Aluminum (Al) toxicity in acid soil reduces crop yields worldwide, especially in the tropical regions. In soil, sulfate decrease Al toxicity and improves plant growth and yield. Here, we aimed to investigate the effects of CaSO4 on Al stress of Al-tolerant accession Col-0 as well as the Al-sensitive accessions, Wei-0 and Ts-5, of in Arabidopsis thaliana using hydroponics. Our research indicates that CaSO4 supply has a significant effect on root growth and malate release compared to CaCl2 under Al stress, especially in Al-sensitive accessions. In response to Al stress, CaSO4 supply enhanced the expression of malate transporter gene AtALMT1 and sulfate transporter gene SULTR3;5, which were regulated by the Al-resistant transcription factor STOP1. Furthermore, knockout lines of SULTR3;5 and SULTR2;1, which are involved in sulfate uptake and translocation, were more Al-sensitive than the wild type under Al stress without CaSO4, and malate release was reduced with decreased AtALMT1 expression. In conclusion, one of the alleviative effects of gypsum application on Al rhizotoxicity is promoted by sulfate through organic acid release mechanism enhancing AtALMT1 expression, alongside the Ca2+ reduction Al3+ activity on the plasma membrane.