Abstract
One of the most stimulating observations in plant evolution is a correlation between the occurrence of geomagnetic field (GMF) reversals (or excursions) and the moment of the radiation of Angiosperms. This led to the hypothesis that alterations in GMF polarity may play a role in plant evolution. Here, we describe a method to test this hypothesis by exposing Arabidopsis thaliana to artificially reversed GMF conditions. We used a three-axis magnetometer and the collected data were used to calculate the magnitude of the GMF. Three DC power supplies were connected to three Helmholtz coil pairs and were controlled by a computer to alter the GMF conditions. Plants grown in Petri plates were exposed to both normal and reversed GMF conditions. Sham exposure experiments were also performed. Exposed plants were photographed during the experiment and images were analyzed to calculate root length and leaf areas. Arabidopsis total RNA was extracted and Quantitative Real Time-PCR (qPCR) analyses were performed on gene expression of CRUCIFERIN 3 (CRU3), copper transport protein1 (COTP1), Redox Responsive Transcription Factor1 (RRTF1), Fe Superoxide Dismutase 1, (FSD1), Catalase3 (CAT3), Thylakoidal Ascorbate Peroxidase (TAPX), a cytosolic Ascorbate Peroxidase1 (APX1), and NADPH/respiratory burst oxidase protein D (RbohD). Four different reference genes were analysed to normalize the results of the qPCR. The best of the four genes was selected and the most stable gene for normalization was used. Our data show for the first time that reversing the GMF polarity using triaxial coils has significant effects on plant growth and gene expression. This supports the hypothesis that GMF reversal contributes to inducing changes in plant development that might justify a higher selective pressure, eventually leading to plant evolution.
Highlights
The Earth’s magnetic field is an inescapable environmental factor for all organisms living on the planet, including plants
Compare the control and the treatment groups by performing analysis of variance (ANOVA) and Tukey’s test with Bonferroni and Dunn-Sidak Adjusted Probability test (0.95% confidence). The aim of this protocol is to provide a method to assess whether reversal of the geomagnetic field (GMF) may affect plant development and gene expression of Arabidopsis thaliana ecotype Columbia 0 (Col 0)
Controls were grown in the same environmental conditions and at normal GMF values
Summary
The Earth’s magnetic field (or equivalently the geomagnetic field, GMF) is an inescapable environmental factor for all organisms living on the planet, including plants. The GMF changed consistently during plant evolution thereby representing an important abiotic stress factor that has been recently considered a potential driving force eventually contributing to plant diversification and speciation 2. Some authors have hypothesized that these transitions periods of low GMF strength might have allowed ionizing radiation from the solar wind to reach the Earth’s surface, thereby inducing a consistent stress to living organisms, which could have been strong enough to induce gene alterations eventually leading to plant evolution 2. The effect of both low and high magnetic field has been thoroughly discussed 1, with a particular focus on the involvement of GMF reversal events on plant evolution 2. This protocol provides an innovative way to evaluate the effect of GMF reversal on plant morphology and gene expression and can be used to assess the potential effect of GMF reversal on other aspects of plant behavior, and thereby guide discussion of the role of GMF reversal on plant evolution
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
