Understanding metal homeostasis in plants
Heavy metals such as Copper (Cu) and Zinc (Zn) are essential for normal plant growth. However, elevated concentrations can result in growth inhibition and toxicity symptoms. Plants possess a range of potential cellular mechanisms that may be involved in the detoxification of heavy metals and thus tolerance to metal stress. Also, plants are a major route for the entry of trace elements into the food chain. Understanding the molecular mechanisms that govern metal homeostasis and accumulation in plants is therefore desirable. The main objective of the 'Upstream signalling, global regulatory control and biochemical function of central components in the zinc homeostasis network: technologies for bio-fortification' (Centzin) project was to study zinc homeostasis and regulation in the model plant organism Arabidopsis thaliana. By constructing various transgenic plants, project partners identified ZIF1, a vacuolar transport protein, as important for zinc tolerance and plant growth. They found that when this protein was abundantly expressed, the plant roots were rich in a metal chelator that worked to reduce the zinc levels. The regulatory mechanism of zinc uptake and transport was further elucidated using gene microarray analysis. Candidate proteins that are implicated in these processes were also identified and characterised. The Centzin project provided significant basic knowledge on the molecular mechanism of zinc regulation and tolerance in plants. The study's insights can be exploited in the bio-fortification of crops to tackle nutritional zinc deficiency.