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Bioelectromagnetism

 

FIGURE 5.7 Time course of LHY, PRR7, and GI relative expression in Arabidopsis thaliana grown under GMF

and NNMF in long day conditions (LD). LHY (A) and PRR7 (B) under LD conditions always show increased gene

expressions when exposed to NNMF, with respect to GMF. GI (C) always shows a reduced gene expression under

NNMF, when compared to GMF. In all plots, white boxes indicate the light phase, whereas black boxes indicate the

dark phase. (Modifed from Agliassa and Mafei (2019).)

modifcations that lead to the production of proteins involved in fowering control, and proteomic stud­

ies are necessary to better asses the role of NNMF on fowering control.

Plant endogenous clock consists of self-sustained interlocked transcriptional/translational feedback

loops whose oscillation regulates many circadian processes, including gene expression. Its free-running

rhythm can be entrained by external cues, which can infuence all clock parameters. Te quantitative

expression (qRT-PCR) of three clock genes (LHY, GI, and PRR7) in time-course experiments under long

day conditions in A. thaliana seedlings exposed to GMF and NNMF conditions reveals that reduction

of GMF to NNMF prompted a signifcant increase of the gene expression of LHY and PRR7, whereas an

opposite trend was found for GI gene expression. Exposure of Arabidopsis to NNMF altered clock gene

amplitude, regardless of the presence of light, by reinforcing the morning loop (Figure 5.7). Terefore,

these results are consistent with the existence of a plant magnetoreceptor that afects the Arabidopsis

endogenous clock (Agliassa and Mafei, 2019).

To comprehensively investigate the infuence of the GMF on A. thaliana photoreceptor signaling,

wild-type (WT) Arabidopsis seedlings and photoreceptor-defcient mutants (cry1cry2, phot1, phyA, and

phyAphyB) were exposed to NNMF and GMF under diferent light wavelengths. For the frst time, the

infuence of the GMF on photoreceptor signaling both under red and blue light was shown (Agliassa

et al., 2018b). Overall, despite the absence of a GMF-induced changes in Arabidopsis seedling photo­

morphogenesis, a signifcant GMF-dependent diferential shoot/root regulation of genes expressed fol­

lowing photoreceptor activation afer 72 hours exposure to GMF with respect to NNMF conditions was

found. In particular, under blue light, the GMF regulation of gene expression appears to be partially

dependent on cryptochrome activation, which is enhanced in terms of increased cry1 phosphoryla­

tion and cry2 degradation. Under red light, the GMF-dependent regulation of light-induced genes is

partially mediated by phyA and phyB, whose activation is altered by cry1, cry2, and phot1 in their inac­

tive form (Figure 5.8). If we consider that the red light response to GMF is not limited to phyA and

phyB (Jeong et al., 2016), the contribution of other phytochromes to this response cannot be excluded.

Terefore, despite the involvement of cryptochrome, and the possibility of a cryptochrome-based RPM,

magnetoreception in Arabidopsis appears to be diferent from the mechanism thought to be responsible

for the ability of migratory songbirds to detect the direction of the GMF. Tese results suggest also

that other processes besides photoreceptor activation could be probably involved in GMF perception

(Agliassa et al., 2018b).

Te reduction of the GMF to NNMF afects the accumulation of metals in plant tissues, mainly iron

(Fe) and zinc (Zn) content, while the content of other metals such as copper (Cu) and manganese (Mn)