Root‐selective expression of AtCAX4 and AtCAX2 results in reduced lamina cadmium in field‐grown Nicotiana tabacum L.

Korenkov, Victor; King, Brian Christopher; Hirschi, Kendal D.; Wagner, George J.

doi:10.1111/j.1467-7652.2008.00390.x

Cited by 83 publications

(35 citation statements)

References 26 publications

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“…Overexpression of AtCAX2 and AtCAX4 in tobacco resulted in Cd accumulation in the roots and a subsequent decrease in the shoots [71]. Four genes that clustered with AtCAX2 and not AtCAX4 (Additional file 13) were identified in N. sylvestris and N. tomentosiformis , suggesting that tobacco CAX gene products orthologous to AtCAX2 and not AtCAX4 may play roles in Cd sequestration in Nicotiana species.…”

Section: Resultsmentioning

confidence: 99%

Reference genomes and transcriptomes of Nicotiana sylvestris and Nicotiana tomentosiformis

et al. 2013

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BackgroundNicotiana sylvestris and Nicotiana tomentosiformis are members of the Solanaceae family that includes tomato, potato, eggplant and pepper. These two Nicotiana species originate from South America and exhibit different alkaloid and diterpenoid production. N. sylvestris is cultivated largely as an ornamental plant and it has been used as a diploid model system for studies of terpenoid production, plastid engineering, and resistance to biotic and abiotic stress. N. sylvestris and N. tomentosiformis are considered to be modern descendants of the maternal and paternal donors that formed Nicotiana tabacum about 200,000 years ago through interspecific hybridization. Here we report the first genome-wide analysis of these two Nicotiana species.ResultsDraft genomes of N. sylvestris and N. tomentosiformis were assembled to 82.9% and 71.6% of their expected size respectively, with N50 sizes of about 80 kb. The repeat content was 72-75%, with a higher proportion of retrotransposons and copia-like long terminal repeats in N. tomentosiformis. The transcriptome assemblies showed that 44,000-53,000 transcripts were expressed in the roots, leaves or flowers. The key genes involved in terpenoid metabolism, alkaloid metabolism and heavy metal transport showed differential expression in the leaves, roots and flowers of N. sylvestris and N. tomentosiformis.ConclusionsThe reference genomes of N. sylvestris and N. tomentosiformis represent a significant contribution to the SOL100 initiative because, as members of the Nicotiana genus of Solanaceae, they strengthen the value of the already existing resources by providing additional comparative information, thereby helping to improve our understanding of plant metabolism and evolution.

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Section: Resultsmentioning

confidence: 99%

Reference genomes and transcriptomes of Nicotiana sylvestris and Nicotiana tomentosiformis

et al. 2013

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“…Root‐specific expression of CAX transporters mitigates Cd 2+ content in tobacco leaves (Korenkov et al . 2007, 2009). Future work may also utilise CAX from microalgae such as Chlamydomonas to remediate Cd 2+ ‐polluted freshwater sites (Pittman et al .…”

Section: The Cax Transporters In Biotechnologymentioning

confidence: 99%

CAX‐ing a wide net: Cation/H⁺ transporters in metal remediation and abiotic stress signalling

2016

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Cation/proton exchangers (CAXs) are a class of secondary energised ion transporter that are being implicated in an increasing range of cellular and physiological functions. CAXs are primarily Ca2+ efflux transporters that mediate the sequestration of Ca2+ from the cytosol, usually into the vacuole. Some CAX isoforms have broad substrate specificity, providing the ability to transport trace metal ions such as Mn2+ and Cd2+, as well as Ca2+. In recent years, genomic analyses have begun to uncover the expansion of CAXs within the green lineage and their presence within non‐plant species. Although there appears to be significant conservation in tertiary structure of CAX proteins, there is diversity in function of CAXs between species and individual isoforms. For example, in halophytic plants, CAXs have been recruited to play a role in salt tolerance, while in metal hyperaccumulator plants CAXs are implicated in cadmium transport and tolerance. CAX proteins are involved in various abiotic stress response pathways, in some cases as a modulator of cytosolic Ca2+ signalling, but in some situations there is evidence of CAXs acting as a pH regulator. The metal transport and abiotic stress tolerance functions of CAXs make them attractive targets for biotechnology, whether to provide mineral nutrient biofortification or toxic metal bioremediation. The study of non‐plant CAXs may also provide insight into both conserved and novel transport mechanisms and functions.

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“…Further, the various transport systems involved in the accumulation of leaf Cd play different roles. Heterologous expression of AtCAX2 and AtCAX4 in all tissues enhanced Cd accumulation in tobacco leaves [15], whereas selective expression only in roots decreased leaf Cd accumulation [14]. Similarly, A. thaliana plants over expressing AtABCC1 and AtABCC2 in all tissues accumulate higher leaf Cd than controls [20].…”

Section: Introductionmentioning

confidence: 96%

“…To date three types of transporters have been identified that are responsible for sequestering Cd into plant vacuoles. They are CAX-type antiporters, such as CAX2 and CAX4 [14], [15], the Heavy Metal ATPase 3 (HMA3) 16–19 and phytochelatin transporters ABCC1 and ABCC2 [20], [21]. Among these, the H + /Cd 2+ -antiporters and HMA3 transport the ionic form of Cd (Cd 2+ ), whereas the phytochelatin transporters transport Cd chelated with phytochelatins [14]–[21].…”

Section: Introductionmentioning

confidence: 99%

Genome-Wide Association Studies Identify Heavy Metal ATPase3 as the Primary Determinant of Natural Variation in Leaf Cadmium in Arabidopsis thaliana

et al. 2012

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Understanding the mechanism of cadmium (Cd) accumulation in plants is important to help reduce its potential toxicity to both plants and humans through dietary and environmental exposure. Here, we report on a study to uncover the genetic basis underlying natural variation in Cd accumulation in a world-wide collection of 349 wild collected Arabidopsis thaliana accessions. We identified a 4-fold variation (0.5–2 µg Cd g−1 dry weight) in leaf Cd accumulation when these accessions were grown in a controlled common garden. By combining genome-wide association mapping, linkage mapping in an experimental F2 population, and transgenic complementation, we reveal that HMA3 is the sole major locus responsible for the variation in leaf Cd accumulation we observe in this diverse population of A. thaliana accessions. Analysis of the predicted amino acid sequence of HMA3 from 149 A. thaliana accessions reveals the existence of 10 major natural protein haplotypes. Association of these haplotypes with leaf Cd accumulation and genetics complementation experiments indicate that 5 of these haplotypes are active and 5 are inactive, and that elevated leaf Cd accumulation is associated with the reduced function of HMA3 caused by a nonsense mutation and polymorphisms that change two specific amino acids.

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Root‐selective expression of AtCAX4 and AtCAX2 results in reduced lamina cadmium in field‐grown Nicotiana tabacum L.

Cited by 83 publications

References 26 publications

Reference genomes and transcriptomes of Nicotiana sylvestris and Nicotiana tomentosiformis

Reference genomes and transcriptomes of Nicotiana sylvestris and Nicotiana tomentosiformis

CAX‐ing a wide net: Cation/H⁺ transporters in metal remediation and abiotic stress signalling

Genome-Wide Association Studies Identify Heavy Metal ATPase3 as the Primary Determinant of Natural Variation in Leaf Cadmium in Arabidopsis thaliana

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Root‐selective expression of AtCAX4 and AtCAX2 results in reduced lamina cadmium in field‐grown Nicotiana tabacum L.

Cited by 83 publications

References 26 publications

Reference genomes and transcriptomes of Nicotiana sylvestris and Nicotiana tomentosiformis

Reference genomes and transcriptomes of Nicotiana sylvestris and Nicotiana tomentosiformis

CAX‐ing a wide net: Cation/H+ transporters in metal remediation and abiotic stress signalling

Genome-Wide Association Studies Identify Heavy Metal ATPase3 as the Primary Determinant of Natural Variation in Leaf Cadmium in Arabidopsis thaliana

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CAX‐ing a wide net: Cation/H⁺ transporters in metal remediation and abiotic stress signalling