Abstract

Silicon (Si) is an abundant element in soils that provides multiple benefits for ryegrass grown under acidic conditions. The positive effects of Si on plants have been mostly associated to a high Si uptake capacity. Nevertheless, there is still little evidence regarding the molecular insights involved in the uptake and transport of Si in ryegrass under optimal or stress conditions. In this study, we identified a Si transporter gene (LpLsi1) from ryegrass cv. Nui, and their expression pattern was analysed. Rapid amplification of cDNA ends (5 and 3 RACE) was performed to isolate a full-length sequence codifying for a Si transporter, and a semi-quantitative and quantitative RT-PCR was used to analyse its expression pattern at 0, 0.5, or 2 mM Si during 0, 3, 6, 9, 12, and 24 h. Our results showed that LpLsi1 was only expressed in roots and down-regulated by Si supply. A high similarity (88%) and a close phylogenetic relationship were found between LpLsi1 and monocot Si influx transporters. Moreover, the analysis of the predicted amino acid sequence indicated that it is a membrane protein that possesses high conservation of Si transport domains that determines the functional selectivity for silicic acid. Our findings provide the first evidence of a Si transporter in ryegrass, supporting its high Si accumulation capacity. This study states a basis for improving the understanding of Si uptake in ryegrass, and the benefits that this forage species can arise from Si nutrition.