Journal Article

Variation in HMA4 gene copy number and expression among Noccaea caerulescens populations presenting different levels of Cd tolerance and accumulation

Meyer, Claire-Lise, Verbruggen, Nathalie, De Groodt, Ruth, Craciun, Adrian R, Hilson, Pierre, Roosens, Nancy, Chen, Jiugeng

2012

Overview

There is huge variability among populations of the hyperaccumulator Noccaea caerulescens (formerly Thlaspi caerulescens) in their capacity to tolerate and accumulate cadmium. To gain new insights into the mechanisms underlying this variability, we estimated cadmium fluxes and further characterized the N. caerulescens heavy metal ATPase 4 (NcHMA4) gene in three populations (two calamine, Saint-Félix-de-Pallières, France and Prayon, Belgium; one serpentine, Puente Basadre, Spain) presenting contrasting levels of tolerance and accumulation. Cadmium uptake and translocation varied among populations in the same way as accumulation; the population with the highest cadmium concentration in shoots (Saint Félix-de-Pallières) presented the highest capacity for uptake and translocation. We demonstrated that the four NcHMA4 copies identified in a previous study are not fixed at the species level, and that the copy truncated in the C-terminal part encodes a functional protein. NcHMA4 expression and gene copy number was lower in the serpentine population, which was the least efficient in cadmium translocation compared to the calamine populations. NcHMA4 expression was associated with the vascular tissue in all organs, with a maximum at the crown. Overall, our results indicate that differences in cadmium translocation ability of the studied populations appear to be controlled, at least partially, by NcHMA4, while the overexpression of NcHMA4 in the two calamine populations may result from convergent evolution.

• Publisher: Oxford University Press [etc.],Oxford University Press,Oxford University Press (OUP)
• Subject: Adenosine Triphosphatases / Adenosine Triphosphatases - genetics / Adenosine Triphosphatases - metabolism / adenosinetriphosphatase / Belgium / Biological and medical sciences / cadmium / Cadmium - metabolism / convergent evolution / enzymology / France / Fundamental and applied biological sciences. Psychology / Gene Dosage / gene expression / Gene Expression Regulation, Plant / genes / genetics / heavy metals / Life Sciences / metabolism / Noccaea caerulescens / Plant physiology and development / Plant Proteins / Plant Proteins - genetics / Plant Proteins - metabolism / serpentine / shoots / smithsonite / Spain / Thlaspi / Thlaspi - enzymology / Thlaspi - genetics / Thlaspi - metabolism / Thlaspi caerulescens