Cloning, functional characterization and heterologous expression of TaLsi1, a wheat silicon transporter gene

Abstract

Silicon (Si) is known to be beneficial to plants, namely in alleviating biotic and abiotic stresses. The magnitude of such positive effects is associated with a plant's natural ability to absorb Si. Many grasses can accumulate as much as 10% on a dry weight basis while most dicots, including Arabidopsis, will accumulate less than 0.1%. In this report, we describe the cloning and functional characterization of TaLsi1, a wheat Si transporter gene. In addition, we developed a heterologous system for the study of Si uptake in plants by introducing TaLsi1 and OsLsi1, its ortholog in rice, into Arabidopsis, a species with a very low innate Si uptake capacity. When expressed constitutively under the control of the CaMV 35S promoter, both TaLsi1 and OsLsi1 were expressed in cells of roots and shoots. Such constitutive expression of TaLsi1 or OsLsi1 resulted in a fourfold to fivefold increase in Si accumulation in transformed plants compared to WT. However, this Si absorption caused deleterious symptoms. When the wheat transporter was expressed under the control of a root-specific promoter (a boron transporter gene (AtNIP5;1) promoter), a similar increase in Si absorption was noted but the plants did not exhibit symptoms and grew normally. These results demonstrate that TaLsi1 is indeed a functional Si transporter as its expression in Arabidopsis leads to increased Si uptake, but that this expression must be confined to root cells for healthy plant development. The availability of this heterologous expression system will facilitate further studies into the mechanisms and benefits of Si uptake.

Can silicon partially alleviate micronutrient deficiency in plants? a review

“…Similar findings were observed in wild and cultivated rice (Mitani-Ueno et al 2013). In addition to rice, similar Si transporters were found in other grasses such as maize, barley and wheat (Mitani et al 2009a, b;Chiba et al 2009;Montpetit et al 2012;Yamaji et al 2012).…”

Silicon Uptake and Transport in Plants: Physiological and Molecular Aspects

“…More recently, TaLsi1 a wheat Si transporter gene has been cloned (Montpetit et al 2012 ). Barley HvLsi1, corn ZmLsi1 and wheat TaLsi1 showed a high level of homology with rice OsLsi1 Montpetit et al 2012 ).…”

“…More recently, TaLsi1 a wheat Si transporter gene has been cloned (Montpetit et al 2012 ). Barley HvLsi1, corn ZmLsi1 and wheat TaLsi1 showed a high level of homology with rice OsLsi1 Montpetit et al 2012 ). Both HvLsi1 and ZmLsi1 show Si infl ux transport activity as OsLsi1, however, with different localization and expression patterns than observed in rice .…”

Growth of Chrysanthemum Cultivars as Affected by Silicon Source and Application Method

“…Silicon accumulation in natural systems is rarely linked to adverse effects in plants, even in those that have a high Si uptake capacity (Cooke and Leishman, 2011). Montpetit et al (2012) also reported that the Si absorption caused leaf necrosis in Arabidopsis and this symptom was proportional to the external Si concentration. Further, they assumed that this symptom was caused by improper regulation of Si uptake or transport in Arabidopsis transformants.…”