Understanding molecular mechanism involved in silicon uptake and deposition in bottle gourd Lagenaria siceraria

Abstract

In order to improve Si derived benefits in crop plants, precise understanding of molecular mechanisms involved in Si uptake and deposition is crucial. In the present study, Si influx and efflux transporter were identified in bottle gourd and fourteen other Cucurbitaceae species. The phylogenetic analysis and syntenic relationships among identified transporters were studied, to understand the evolution of Si uptake mechanism in Cucurbitaceae lineage. In the bottle gourd, Si quantification performed in different tissues showed the highest amount of Si deposition in leaves. Moreover, significant genotypic variation for Si accumulation was also observed among sixteen diverse bottle gourd genotypes. A high amount of Si accumulation was seen in the shaft of leaf trichome in bottle gourd evaluated with the help of a scanning electron microscope coupled with an energy dispersive X-ray (SEM-EDX). The real-time quantitative PCR analysis performed at different time intervals after Si and arsenic supplementation revealed the differential expression of LsiNIP2-1 and LsiLsi2 in root and leaves of bottle gourd. The increased expression of LsiNIP2-1 and LsiLsi2 in the presence of Si was confirmed using the split root experiment. The Si uptake kinetics evaluated with single root assay confirmed the Si uptake ability of bottle gourd. The LsiNIP2-1 and LsiLsi2 were functionally characterized by performing yeast drop-out assay at different concentrations of arsenic, boric acid, and germanium. Plasma membrane specific localization of LsiNIP2-1 was observed with the transient gene expression in tobacco epidermal cells. The phenomics, transcriptomics, and root phenotyping analysis were performed in the bottle gourd plants supplement with Si, cadmium, and Si plus cadmium. The detailed information on evolution, expression, Si accumulation, elemental profiling, transcriptomics, phenomics, and the role of Si in presence of heavy metals will help to better understand the Si transporters in Cucurbitaceae, particularly in bottle gourd.