Il ruolo di WHIRLY2, proteina mitocondriale dei nucleoidi, nello sviluppo e nella risposta allo stress nelle piante.

In the last few years, the importance of organelles as central coordinators of plant responses to internal/external stimuli has become increasingly important. Mitochondria have a fundamental role in energy production, but play also a role as stress sensors of environmental stimuli, being a component of a complex communication network between organelles and nucleus. WHIRLYs are plant-specific proteins that have been characterized as ssDNA-binding proteins because of a characteristic conserved DNA-binding domain. In Arabidopsis, the WHIRLY family includes three members: WHIRLY1, WHIRLY2 and WHIRLY3, presenting specific target sequences that localize them in the plastids and nucleus (WHIRLY1, WHIRLY3) or in the mitochondria (WHIRLY2). WHY2 among the proteins involved in mtDNA repair is the most abundant and evidences suggest an important role of it in mitochondrial genome replication necessary to complete mtDNA activity. Recent results on WHY2 show a link between mtDNA stability and proper mitochondrial morphology, dynamics and functionality, indicating a fundamental role of this protein in mitochondrial activity during development and stress responses. Failure in maintaining the mitochondrial genome stability results in the accumulation of mutations and genomic rearrangements that can become deleterious. In the present work data are reported showing the relationship between mtDNA maintenance, high levels of WHY2 and the response to abiotic stress. Evidences show that WHY2 plays a role in the response to different abiotic stresses. Our results also suggest an involvement of WHY2 protein in retrograde signalling in response to abiotic stresses. The study of mitochondrial proteins, as WHY2, contributes to open up a new conception of the role of mitochondria as a stress response center and to unveil molecular mechanisms underlying the communication between mitochondria and nucleus in response to stress.