Transcriptome Response of Metallicolous and a Non-Metallicolous Ecotypes of Noccaea goesingensis to Nickel Excess.

Agnieszka Domka,Magdalena Hubalewska-Mazgaj,Piotr Rozpądek,Roman Jan Jędrzejczyk,Cristina Gonnelli,Federico Martinelli,Katarzyna Turnau,Jubina Benny,Markus Puschenreiter,Rafał Ważny

doi:10.3390/plants9080951

Abstract

Root transcriptomic profile was comparatively studied in a serpentine (TM) and a non-metallicolous (NTM) population of Noccaea goesingensis in order to investigate possible features of Ni hyperaccumulation. Both populations were characterised by contrasting Ni tolerance and accumulation capacity. The growth of the TM population was unaffected by metal excess, while the shoot biomass production in the NTM population was significantly lower in the presence of Ni in the culture medium. Nickel concentration was nearly six- and two-fold higher in the shoots than in the roots of the TM and NTM population, respectively. The comparison of root transcriptomes using the RNA-seq method indicated distinct responses to Ni treatment between tested ecotypes. Among differentially expressed genes, the expression of IRT1 and IRT2, encoding metal transporters, was upregulated in the TM population and downregulated/unchanged in the NTM ecotype. Furthermore, differences were observed among ethylene metabolism and response related genes. In the TM population, the expression of genes including ACS7, ACO5, ERF104 and ERF105 was upregulated, while in the NTM population, expression of these genes remained unchanged, thus suggesting a possible regulatory role of this hormone in Ni hyperaccumulation. The present results could serve as a starting point for further studies concerning the plant mechanisms responsible for Ni tolerance and accumulation.

Highlights

Plants able to grow and reproduce on potentially toxic metal-rich soils without symptoms of toxicity are termed as “metallophytes” [1]
Out of the genes classified into the abiotic stress category, five genes were up-regulated in the NTM ecotype: HSP26.5-P (26.5 kDa class I small heat shock protein-like, At1g52560), chaperone DnaJ-domain superfamily protein (At1g72416), HSP17.6A-CI
The comparison of the transcriptome of two N. goesingensis ecotypes, that differed in Ni accumulation capacity and tolerance, enabled us to provide an insight into mechanisms underlying

Summary

Introduction

Plants able to grow and reproduce on potentially toxic metal-rich soils without symptoms of toxicity are termed as “metallophytes” [1]. Plants 2020, 9, 951 mechanisms to cope with metal toxicity as far as metal concentration in the soil remains within tolerance ranges [3,4]. This adaptation may lead to the speciation and evolution of endemic taxa, occurring solely on polluted sites and termed as obligate metallophytes [5,6]. In some plant species, metals may be accumulated in shoots in concentrations beyond those present in roots (reviewed by Krämer [9]) This adaptation to metal toxicity evolved in a specific group of plants called metal hyperaccumulators.

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