5

Magnetoreception

in Plants

5.1

Introduction .......................................................................................191

5.2

Mechanism of Magnetoreception in Plants.................................. 192

Te Radical-Pair Mechanism

5.3

Light-Dependent Magnetoreception ............................................. 196

5.4

Light-Independent Magnetoreception ..........................................203

5.5

Magnetic Fields with a Higher Intensity with Respect to

Geomagnetic Field............................................................................206

Massimo Emilio

5.6

Conclusions........................................................................................ 210

Maffei

References...................................................................................................... 210

5.1 Introduction

As sessile organisms, plants have evolved both constitutive and inducible responses to the changing

environment. Several environmental factors afect plant growth and development. Among them, the

Earth magnetic feld or geomagnetic feld (GMF) is an environmental component of our planet. It is

fairly homogeneous and relatively weak. Te strength of the GMF at the surface of the Earth ranges

from <30 μT in an area that includes most of South America and South Africa (the so-called South

Atlantic anomaly) to over 60 μT around the magnetic poles in northern Canada, the south of Australia,

and in parts of Siberia (Occhipinti et al., 2014). Plants that are known to sense diferent wavelengths of

light, respond to gravity, and react to touch and electrical signals cannot avoid the presence of the GMF

(Mafei, 2014). While plant phototropism, gravitropism, hydrotropism, and autostraightening have been

thoroughly documented (Harmer and Brooks, 2018), possible efects of the GMF on plant growth and

development are still a matter of discussion. Nevertheless, a growing body of evidence indicates that

plants do react to varying magnetic feld (MF) fuxes at values both below and above the GMF (Teixeira

da Silva and Dobranszki, 2016; Radhakrishnan, 2019).

Reduction of the GMF to Near Null Magnetic Field (NNMF; about 30 nT) has been shown to infu­

ence many plant biological processes (Xu et al., 2013; Mafei, 2014). In previous studies aimed at evaluat­

ing the efect of GMF reversal on plants, we found diferential root/shoot responses in plant morphology

and in the expression of some genes (e.g., Cruciferin 3, Copper Transport Protein1, and Redox Responsive

Transcription Factor1) (Bertea et al., 2015). Tis fnding is in agreement with the current view that the

magnetic reaction could change the ratio of redox states in the cryptochrome photocycle to alter the bio­

logical activity of cryptochrome (Pooam et al., 2019; Hammad et al., 2020). We also found that the GMF

impacted the fowering time by diferentially regulating leaf and foral meristem genes (Agliassa et al.,

2018a) and by altering the signaling of cryptochrome and phytochrome. In particular, blue light expo­

sure led to a partial association between the GMF-induced changes in gene expression and an alteration

in cryptochrome activation (Agliassa et al., 2018b). Te GMF also afected plant mineral nutrition by

DOI: 10.1201/9781003181354-5

191