Research

Cobbett Lab

Topic 1: Heavy Metal Transporting P-type ATPases are essential for zinc homeostasis

Using mutants we have shown that members of a family of heavy metal transporting P-type ATPases (the HMAs) are essential for zinc homeostasis. These transporters are expressed in the vascular tissue and in developing anthers. Consistent with this the mutants fail to transport zinc from root to shoot and are unable to develop viable pollen. We are continuing to characterise the roles of these transporters in zinc homeostasis in plants.

Figure 1. hma2;hma4 double mutants showing stunting and chlorosis without exogenous supply of Zn. The phenotypes can be rescued by application of 1mM Zn.

Figure 2a. HMA2 is expressed in the vascular tissues of (a) seedling, (b) roots, (c) leaf (d) stem and (e) inflorescence.

Figure 2b. In reproductive tissues, HMA2 is expressed in immature anthers (a), the site of pollen production (visible through the petals of an unopened flower). Cross section of an anther show GUS staining localised to the tapetum (e), a single layer of cells surrounding the locule which is believed to provide nutrients to developing pollen. Staining of mature filaments, but not anthers, is visible in mature flower (b). Staining of developing silique (c) and mature silique is also shown.

Figure 3. HMA Expression in yeast. In a Zn-dependent zrt1,zrt2 yeast mutant, both HMA2 (H2) and HMA4 (H4) increase Zn-dependency at 1.5µM, as compared to the controls (C).

Topic 2: Major Facilitator Superfamily transporters have an unexpected role in zinc homeostasis

Topic 3: Glutathione is essential for growth and development and plays an important role in responses to heavy metal stress

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