(New) Evidences of the interplay between mitochondrial proteins and cytokinin signaling pathways

MENCIA R,; CÉCCOLLI G,; TORTI P,; GONZALEZ DH,; WELCHEN, E.

Congreso; 11th International Congress of Plant Molecular Biology; 2015

The aim of our group is to identify new proteins involved in defense mechanisms against oxidative stress in Arabidopsis thaliana. Plants overexpressing (OE) one of our candidate protein exhibit interesting phenotypic characteristics like larger rosette size, higher biomass and increased resistance to hemibiotrophic pathogens infection compared to Wt plants. These characteristics could be a consequence of higher cytokinin content or differences on sensitivity and signaling pathways. By transcriptomic analysis of the OE-plants and T-DNA insertional mutants we identified a group of genes, enriched in those connected with cytokinin synthesis and response. By real time PCR we confirm a decreased level of transcripts encoding for proteins belonging to the type-A negative responses regulators (AtARRs). We also detected higher transcript levels of genes involved in the cytokinin biosynthesis (AtIPT) and signaling pathways (AtAHK). These results were reinforced by analyzing the expression pattern of GUS gene in Arabidopsis OE-plants transformed with type-A ARRs promoters fused to the reporter gene. Besides, with the aim of analyze if this pathway is required for the OE-plant phenotype, we overexpress our candidate in the background of Atahp quadruple mutant (ahp1/ahp2/ahp3/ahp4) and Atarr sextuple mutant (arr3/arr4/arr5/arr6/arr8/arr9). Finally, by using confocal microscopy we observed that this new protein under study is specifically localized into the plant mitochondria. Our results constitute new evidences about the interplay between mitochondrial activities and hormonal control of growth and defenses in plants.