Characterization of the Silicon Uptake System and Molecular Mapping of the Silicon Transporter Gene in Rice 1

Faculty of Agriculture, Kagawa University, Miki-cho, Kita-gun, Kagawa 761-0795, Japan.
Plant physiology (Impact Factor: 6.84). 11/2004; 136(2):3284-9. DOI: 10.1104/pp.104.047365
Source: PubMed


Rice (Oryza sativa L. cv Oochikara) is a typical silicon-accumulating plant, but the mechanism responsible for the high silicon uptake by the roots is poorly understood. We characterized the silicon uptake system in rice roots by using a low-silicon rice mutant (lsi1) and wild-type rice. A kinetic study showed that the concentration of silicon in the root symplastic solution increased with increasing silicon concentrations in the external solution but saturated at a higher concentration in both lines. There were no differences in the silicon concentration of the symplastic solution between the wild-type rice and the mutant. The form of soluble silicon in the root, xylem, and leaf identified by (29)Si-NMR was also the same in the two lines. However, the concentration of silicon in the xylem sap was much higher in the wild type than in the mutant. These results indicate that at least two transporters are involved in silicon transport from the external solution to the xylem and that the low-silicon rice mutant is defective in loading silicon into xylem rather than silicon uptake from external solution to cortical cells. To map the responsible gene, we performed a bulked segregant analysis by using both microsatellite and expressed sequence tag-based PCR markers. As a result, the gene was mapped to chromosome 2, flanked by microsatellite marker RM5303 and expressed sequence tag-based PCR marker E60168.

Download full-text


Available from: Takashi Iwashita, Oct 10, 2015
24 Reads
  • Source
    • "Like plants, diatoms contain several silicon transporters, often arranged in gene families, but these transporters are different in both their structures and functions from their plant counterparts (Hildebrand et al., 1998; Ma et al., 2004). Most tellingly, ectopic expression of a silicon transporter gene from diatoms in transgenic tobacco had no significant impact on silicon uptake, indicating fundamental differences in silicon absorption between plants and diatoms (Ma et al., 2004). These differences notwithstanding, insights into the significance and regulation of silicon-mediated processes in diatoms may potentially shed new light on the poorly understood role of silicon in plant stress responses. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Plants are constantly threatened by a wide array of microbial pathogens. Pathogen invasion can lead to vast yield losses and the demand for sustainable plant-protection strategies has never been greater. Chemical plant activators and selected strains of rhizobacteria can increase resistance against specific types of pathogens but these treatments are often ineffective or even cause susceptibility against others. Silicon application is one of the scarce examples of a treatment that effectively induces broad-spectrum disease resistance. The prophylactic effect of silicon is considered to be the result of both passive and active defences. Although the phenomenon has been known for decades, very little is known about the molecular basis of silicon-afforded disease control. By combining knowledge on how silicon interacts with cell metabolism in diatoms and plants, this review describes silicon-induced regulatory mechanisms that might account for broad-spectrum plant disease resistance. Priming of plant immune responses, alterations in phytohormone homeostasis, regulation of iron homeostasis, silicon-driven photorespiration and interaction with defence signalling components all are potential mechanisms involved in regulating silicon-triggered resistance responses. Further elucidating how silicon exerts its beneficial properties may create new avenues for developing plants that are better able to withstand multiple attackers.
    Journal of Experimental Botany 12/2012; 64(5). DOI:10.1093/jxb/ers329 · 5.53 Impact Factor
  • Source
    • "However, Si-containing fertilizers are routinely applied to several crops including rice (Pereira et al., 2004) and sugarcane (Savant et al., 1999) to increase crop yield and quality. Increased Si supply improves the structural integrity of crops and may also improve plant tolerance to diseases, drought and metal toxicities (Epstein, 1999; Richmond and Sussman, 2003; Ma et al., 2004). Epstein (2001) cited some scientifically proven examples regard beneficial effects of Si such as: increased insect and disease resistance; reduced mineral toxicities and reduced drought and frost tolerance. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Field experiments were conducted to evaluate the effect of foliar spray of soluble silicic acid on growth and yield parameters of wetland rice. The results revealed a significant effect on achieving higher grain and straw yield with foliar silicic acid over control. Foliar spray of silicic acid at 2 and 4 ml L−1 increased the grain and straw yield and application of 8 ml L−1 decreased the yield. Foliar spray of silicic acid at 4 ml L−1 along with half dose of recommended pesticide effectively increased the yields over all other treatments. The content and uptake of silicon in grain and straw was recorded higher with the foliar spray of silicic acid over control. This investigation concludes that application of silicic acid at 4 ml L−1 along with half dose of recommended pesticide as foliar spray increased the grain and straw yield, besides Si content and its uptake over control.
    Journal of Plant Nutrition 09/2011; 34(12-12):1883-1893. DOI:10.1080/01904167.2011.600414 · 0.49 Impact Factor
  • Source
    • "Lsi1 is also permeable to silicic acid from both directions (Mitani et al., 2008). However, Lsi1 mutation has a profound effect on Si accumulation in rice in both short-and long-term experiments (Ma et al., 2004, 2006). The difference between Si and As can be explained by the highly efficient pumping of Si toward xylem in rice (Mitani & Ma, 2005). "
    [Show abstract] [Hide abstract]
    ABSTRACT: *When supplied with arsenate (As(V)), plant roots extrude a substantial amount of arsenite (As(III)) to the external medium through as yet unidentified pathways. The rice (Oryza sativa) silicon transporter Lsi1 (OsNIP2;1, an aquaporin channel) is the major entry route of arsenite into rice roots. Whether Lsi1 also mediates arsenite efflux was investigated. *Expression of Lsi1 in Xenopus laevis oocytes enhanced arsenite efflux, indicating that Lsi1 facilitates arsenite transport bidirectionally. *Arsenite was the predominant arsenic species in arsenate-exposed rice plants. During 24-h exposure to 5 mum arsenate, rice roots extruded arsenite to the external medium rapidly, accounting for 60-90% of the arsenate uptake. A rice mutant defective in Lsi1 (lsi1) extruded significantly less arsenite than the wild-type rice and, as a result, accumulated more arsenite in the roots. By contrast, Lsi2 mutation had little effect on arsenite efflux to the external medium. *We conclude that Lsi1 plays a role in arsenite efflux in rice roots exposed to arsenate. However, this pathway accounts for only 15-20% of the total efflux, suggesting the existence of other efflux transporters.
    New Phytologist 02/2010; 186(2):392-9. DOI:10.1111/j.1469-8137.2010.03192.x · 7.67 Impact Factor
Show more