The blue light receptor Phototropin 1 suppresses lateral root growth by controlling cell elongation

Abstract

We investigated the relationship between the blue light receptor phototropin 1 (phot1) and lateral root growth in Arabidopsis thaliana seedlings. Fluorescence and confocal microscopy images, as well as PHOT1 mRNA expression studies provide evidence that it is highly expressed in the elongation zone of lateral roots where auxin is accumulating. However, treatment with the auxin transport inhibitor N-1-naphthylphthalamic acid significantly reduced PHOT1 expression in this zone. In addition, PHOT1 expression was higher in darkness than in light. The total number of lateral roots was higher in the phot1 mutant than in wild-type Arabidopsis. Cells in the elongation zone of lateral roots of the phot1 mutant were longer than those of wild-type lateral roots. These findings suggest that PHOT1 plays a role(s) in elongation of lateral roots through the control of an auxin-related signalling pathway.

Light modulates the root tip excision induced lateral root formation in tomato

“…There is already evidence that phototropin, the blue absorbing photoreceptors regulate LRF. 24 Our experiments indicate that this process may also be aided by phytochrome. Several lines of evidences indicate that light quality received by shoot also affects root function and morphology.…”

“…22,23 The total number of LR were higher in the phototropin 1 mutant than in wild-type Arabidopsis. 24 To understand the interrelationship between LRF and root tip excision, we examined this response in tomato seedlings. The results obtained in this study demonstrate that root tip excisionmediated LRF in tomato seedlings is modulated by light.…”

Expression of Root Genes in Arabidopsis Seedlings Grown by Standard and Improved Growing Methods

“…In contrast, early reports suggested that the expression level of phytochromes [30,31], cryptochrome [3], and phototropins [32] in roots is light dependent. For example, the expression level of PHOT1 in roots depends on the depth of roots grown beneath the soil surface [32]. However, effects of the gradient-decreased light intensity on the root photoreceptor expression were not reported.…”

Light Signaling, Root Development, and Plasticity

“…In the PHY box, "L" stands for protein levels in light and "D" for protein levels in the dark. Source data: for all, BAR eFP browser (http://bar.utoronto.ca/efp/cgi-bin/efpWeb.cgi), PHYs (Somers and Quail, 1995;Goosey et al, 1997;Tó th et al, 2001;Sharrock and Clack, 2002;Salisbury et al, 2007), PHOTs (Sakamoto and Briggs, 2002;Moni et al, 2015), CRYs (Tó th et al, 2001), and UVR8 (Rizzini et al, 2011). and pathogens (Ballaré et al, 2012;Galvão and Fankhauser, 2015). UV-B (280-315 nm) is perceived by UVR8, which uses a structure based on tryptophans and a complex salt bridge network.…”