Silicon transporters Lsi1 and Lsi2 differentially regulate dimethylarsinic acid uptake, toxicity, and grain...

Accumulation of dimethylarsinic acid (DMA) in reproductive organs is the primary cause of rice straighthead disease, a physiological disorder that can result in substantial yield losses. To elucidate the role of silicon (Si) in mitigating DMA toxicity and accumulation in rice, this study evaluated the effects of Si supplementation on DMA toxicity, accumulation, and plant performance in two Si transporter mutants (lsi1 and lsi2) and their wild-type (ZH11) through hydroponic and pot experiments. The lsi1 mutant exhibited significantly higher resistance to DMA toxicity, associated with a 50 % reduction in DMA uptake compared to ZH11 and lsi2. In ZH11 and lsi2, Si supplementation effectively reduced root arsenic (As) concentration by 50 % and alleviated DNA damage, while its effects were limited in lsi1 due to impaired Si uptake. In soil-grown plants, Si application improved grain yield and biomass in ZH11 and lsi2, but had negligible effects in lsi1. In conclusion, Si effectively mitigates DMA-induced toxicity by limiting DMA accumulation and promoting plant growth, primarily through the action of the Si transporter Lsi1. These findings highlight the dual role of the Si transporter Lsi1 in mediating both DMA uptake and straighthead disease resistance, while also emphasizing the critical importance of Si in alleviating DMA toxicity in rice.