In Arabidopsis thaliana Cadmium Impact on the Growth of Primary Root by Altering SCR Expression and Auxin-Cytokinin Cross-Talk

Abstract

Cadmium is one of the most widespread pollutant in both terrestrial and marine environment, and its inhibitory effect on plant growth has been largely demonstrated. However, the molecular mechanisms underlying Cd toxicity in plant and mainly in root, as the first organ sensing soil heavy metals, need to be better investigated. To this aim, in the present work we analyzed the growth and the organization of Arabidopsis thaliana primary root in seedlings exposed to Cd (25 and 50 μM) for 8 days starting from germination. Root length, root meristem size, and organization were evaluated together with the behavior of some of the major molecular players in root growth and patterning. In particular, by using different GFP transgenic lines, we monitored: (i) the expression pattern of WOX5 and SCR transcription factors involved in the establishment and maintenance of stem cell niche and in the control of meristem size; (ii) the expression pattern of the IAA-inducible pDR5::GFP reporter, PIN 1, 2, 3, 7 auxin carriers and TCSn::GFP cytokinin-sensitive sensor as relevant components of hormone circuit controlling root growth. We report that Cd exposure inhibits primary root growth via affecting RAM stem cell niche and root radial pattern. At the molecular level, an impairment of auxin maximum accumulation at the root tip, related to a down-regulation and mislocalisation of PIN proteins, and an enhancement of TCSn::GFP cytokinin-sensitive sensor signal is also detected under Cd treatment, thus suggesting an alteration in the homeostasis of auxin/cytokinin signaling. Moreover, and for the first time Cd toxicity on root growth and pattern has been related to a misexpression of SCR transcription factors which is known to interplay with auxin/cytokinin cross-talk in the control of RAM maintenance and activity.

The polyadenylation factor FIP1 is important for plant development and root responses to abiotic stresses

“…We found that salt treatment and fip1‐2 mutation affected poly(A) site usage in a significant number of genes associated with the response to cadmium (Table S3a,b). Treating seedlings with Cd, a non‐essential toxic heavy metal, inhibits root growth (Yuan and Huang, ) and affects gene expression (Li et al ., ), probably by affecting SCR expression (Bruno et al ., ) and auxin signaling (Yuan and Huang, ). First, we analyzed whether Cd affects FIP1 expression.…”

ZmbZIP4 Contributes to Stress Resistance in Maize by Regulating ABA Synthesis and Root Development

“…IAA8 (INDOLEACETIC ACID-INDUCED PROTEIN8), IAA14, ZmARFs (AUXIN-RESPONSIVE FACTORS), SCR (SCARECROW), and LRP1 (LATERAL ROOT PRIMORDIUM PROTEIN1) were reported to be involved in root development, especially lateral root formation (Smith and Fedoroff, 1995;Lim et al, 2005;Krichevsky et al, 2009;Arase et al, 2012;Bruno et al, 2017). The ZmbZIP4 overexpression lines had longer primary roots and seminal roots as well as more lateral roots and LRP than the wild type, while the mutants showed opposite changes (Fig.…”

MhNRAMP1 From Malus hupehensis Exacerbates Cell Death by Accelerating Cd Uptake in Tobacco and Apple Calli

“…Cd in soil is easily taken up by plant roots and causes severe phytotoxicity to plants ( Zare et al., 2018 ). Excessive Cd restricts nutrient uptake ( Yamaguchi et al., 2016 ; Wang et al., 2017 ; Cengiz et al., 2019 ; Wu et al., 2019 ), decreases photosynthetic efficiency ( Pereira de Araújo et al., 2017 ), delays seed germination ( Zhang et al., 2014 ), and impairs plant growth and development ( Bruno et al., 2017 ; Sofo et al., 2017 ), resulting in serious production reductions ( Abbas et al., 2018 ; Guo et al., 2018 ; Chen et al., 2019 ). The current study shows that some orchard soils and even fruits have been contaminated by Cd, which threatens the growth of fruit trees and the edible safety of fruits ( Cheng et al., 2015 ).…”