Physiologic and Metabolic changes associated to altered expression of UKCCT in Arabidopsis

OSELLA, ANA VIRGINIA; VALLE, ESTELA MARTA; ZANOR, MARÍA INÉS

Rosario

Congreso; Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2014

UKCCT belongs to a large family of uncharacterized genes which possess just a single CCT domain. CCT domain-containing proteins are considered to function as transcriptional regulators implicated in diverse processes such as photoperiodic flowering, regulation of circadian rhythms, light signalling and gene expression in response to sugars. During the photoperiod, fine control of redox homeostasis is needed to prevent ROS overload due to excess light. Failure to maintain redox balance results in growth defects or initiation of cell death. Arabidopsis plants over-expressing UKCCT (OE-UKCCT) show a deregulation of O2- and H2O2 levels, chlorotic and hyponastic leaves resembling the phenotype observed in cat2 mutants. The analysis of the mechanisms probably involved in the detoxification of ROS revealed that the high production of H2O2 overwhelms its clearance even total catalase activity is increased. Moreover, these plants accumulated differentially metabolites related to stress such as proline, raffinose and galactinol. Interestingly, OE-UKCCT lines develop spontaneous lesions where intensity of damage seems to be photoperiod dependent. A detailed phenotypic analysis of mutant lines of this gene revealed a higher photosynthetic performance and increased seed set. Our working hypothesis is that UKCCT could act in the regulation of ROS homeostasis during photoperiod.