Il silicio, elemento “essenziale” per alcune colture agrarie

Jian Feng Ma [Istituto di ricerca per le biorisorse, Università di Okayama, Chuo 2-20-1, Kurashiki, Japan]

Silicon (Si) is the second most abundant element in soil and all plants contain Si in their tissues. Although silicon has not been recognized as an essential element for plant growth, the beneficial effects of Si have been observed in a wide variety of plant species. Silicon plays an important role in increasing the resistance to both biotic and abiotic stresses including diseases, pests, lodging, drought, and nutrient imbalance. The beneficial effects of Si to plants are mainly associated with its high deposition in tissues that enhances their strength and rigidity. However, Si may play an active role in enhancing host resistance to plant diseases by stimulating some defense reaction mechanism(s). One the other hand, plant species differ greatly in Si accumulation resulting from the ability of roots to take up Si. Recently, the first gene encoding Si transporter has recently been identified in rice, a typical Si-accumulating plant. The transporter encoded by this gene shows a high specificity for Si, and is localized at the distal side of both exodermis and endodermis, indicating that this transporter is responsible for the influx of Si from the external solution to the root cells. Cloning of more genes from different plant species in future will help to understand the molecular mechanisms of Si uptake. Furthermore, since many plants are not able to accumulate Si at levels high enough to be beneficial, genetic manipulation of the root’s Si uptake capacity may help plants to accumulate more Si, thereby improving the plants ability to overcome biotic and abiotic stresses.

Keywords: Silicon, stress, beneficial effect, transporter, accumulation

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Ma, J.F. (2007) 'Il silicio, elemento “essenziale” per alcune colture agrarie', Italus Hortus, 14(4), pp. 1-13.