Journal article
Tandem quadruplication of HMA4 in the zinc (Zn) and cadmium (Cd) hyperaccumulator Noccaea caerulescens
Plos One, Vol.6(3), pp.1-9
2011
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Abstract
<p>Zinc (Zn) and cadmium (Cd) hyperaccumulation may have evolved twice in the Brassicaceae, in <em>Arabidopsis halleri</em> and in the <em>Noccaea</em> genus. Tandem gene duplication and deregulated expression of the Zn transporter, <em>HMA4</em>, has previously been linked to Zn/Cd hyperaccumulation in <em>A. halleri</em>. Here, we tested the hypothesis that tandem duplication and deregulation of <em>HMA4</em> expression also occurs in <em>Noccaea</em>.</p>
<p>A <em>Noccaea caerulescens</em> genomic library was generated, containing 36,864 fosmid pCC1FOS™ clones with insert sizes ~20–40 kbp, and screened with a PCR-generated <em>HMA4</em> genomic probe. Gene copy number within the genome was estimated through DNA fingerprinting and pooled fosmid pyrosequencing. Gene copy numbers within individual clones was determined by PCR analyses with novel locus specific primers. Entire fosmids were then sequenced individually and reads equivalent to 20-fold coverage were assembled to generate complete whole contigs.</p>
<p>Four tandem <em>HMA4</em> repeats were identified in a contiguous sequence of 101,480 bp based on sequence overlap identities. These were flanked by regions syntenous with up and downstream regions of <em>AtHMA4</em> in <em>Arabidopsis thaliana.</em> Promoter-reporter <em>β-glucuronidase</em> (<em>GUS</em>) fusion analysis of a <em>NcHMA4</em> in <em>A. thaliana</em> revealed deregulated expression in roots and shoots, analogous to <em>AhHMA4</em> promoters, but distinct from <em>AtHMA4</em> expression which localised to the root vascular tissue.</p>
<p>This remarkable consistency in tandem duplication and deregulated expression of metal transport genes between <em>N. caerulescens</em> and <em>A. halleri</em>, which last shared a common ancestor >40 mya, provides intriguing evidence that parallel evolutionary pathways may underlie Zn/Cd hyperaccumulation in Brassicaceae.</p>
Details
- Title
- Tandem quadruplication of HMA4 in the zinc (Zn) and cadmium (Cd) hyperaccumulator Noccaea caerulescens
- Creators
- S O'Lochlainn - University of NottinghamHelen Bowen - University of WarwickR O Fray - University of NottinghamJ P Hammond - University of NottinghamG J King - Rothamsted Research, UKN S Graham - Southern Cross UniversityMartin R Broadley - University of Nottingham
- Publication Details
- Plos One, Vol.6(3), pp.1-9
- Identifiers
- 1063; 991012820621902368
- Academic Unit
- Faculty of Science and Engineering; Southern Cross Plant Science; Science
- Resource Type
- Journal article