Early Responses of Maize Seedlings to Cu Stress Include Sharp Decreases in Gibberellins and Jasmonates in the Root Apex

CL MATAYOSHI; LB PENA; V ARBONA; A GÓMEZ-CADENAS; SM GALLEGO

PROTOPLASMA

SPRINGER WIEN

Lugar: Viena; Año: 2020

0033-183X

Copper (Cu) interferes with numerous biological functions in plants, including plant growth, which is partly governed byplant hormones. In the present study, Cu stress effect on the roots of pre-emerging maize seedlings in terms of growth,nutrient composition, protein modifications, and root hormone homeostasis was investigated, focusing on possiblemetabolic differences between the root apex and the rest of the root tissues. Significant decreases in root length androot biomass after 72 h of Cu exposure (50 and 100 μM CuCl2), accompanied by reductions in Ca, Mg, and P rootcontents, were found. Cu also generated cell redox imbalance in both root tissues and revealed by altered enzymatic andnon-enzymatic antioxidant defenses. Oxidative stress was evidenced by an increased protein carbonylation level in bothtissues. Copper also induced protein ubiquitylation and SUMOylation and affected 20S proteasome peptidase activitiesin both tissues. Drastic reductions in ABA, IAA, JA (both free and conjugated), GA3, and GA4 levels in the root apexwere detected under Cu stress. Our results show that Cu exposure generated oxidative damage and altered root hormonalhomeostasis, mainly at the root apex, leading to a strong root growth inhibition. Severe protein post-translationalmodifications upon Cu exposure occurred in both tissues, suggesting that even when hormonal adjustments to copewith Cu stress occurred mainly at the root apex, the entire root is compromised in the protein turnover that seems to benecessary to trigger and/or to sustain defense mechanisms against Cu toxicity.