Effects of Redox Imbalance on wheat root apical meristem: Modifications of the transition zone

AAE MENDEZ; LB PENA; M SMEHILOVA; HF CAUSIN; SM GALLEGO

Congreso; L Reunión Anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular; 2014

Adverse environmental conditions affect plant growth. We studied the response of the wheat root apical meristem (RAM) to Cd (a redox inactive metal), Cu (a redox active metal), MV (methyl viologen) and H2O2 (two well-known oxidative stressors). Seeds of Triticum aestivum L. were floated for 48 h on distillated water (control) or in the presence of the corresponding stressor. The concentrations that altered root length (10 µM Cd2+, 5 µM Cu2+, 0.5 µM MV and 1 mM H2O2) hastened cell displacement from the cell division zone to the elongation/differentiation zone, resulting in a shortened meristem. Metals increased reactive oxygen species in the root apex as indicated by the fluorogenic probes 2´,7´-dichlorodihydrofluorescein diacetate and dihydroethidium. Treatments increased protein oxidation. Transcription in the RAM of genes related to the cell cycle G1/S transition (rdr, pcna, mcm2) was down regulated by oxidative conditions. This effect might be associated to the alteration of cytokinins (CKs) homeostasis, as suggested by the analysis of transcripts related to CKs metabolism by qRT-PCR. Four from five expansin genes transcripts analyzed (TaEXPA5, TaEXPA6, TaEXPA8, TaEXPB8 and TaEXPB10) were upregulated by the treatments. These results indicate the importance of the transition zone as an oscillatory zone that connects root growth and development with environmental cues.