Functional and phenotypic characterization of two genes member of Arabidopsis Oxr Family

COLOMBATTI, FRANCISCO; GARCÍA, LUCILA; GONZALEZ, DANIEL H.; WELCHEN, ELINA

Congreso; 46 Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2010

Reactive oxygen species are chemical compunds produced in all arobic organisms. One particular characteristic is their high reactivity against cell molecules. We found, by means of a particular E. Coli strain that At2g05590 and At4g39870 (called Ox2 and Ox4 respectively) are able to confer resistance to oxidative stress. Then, we overexpressed these genes in A. thaliana and selected plants with higher levels of expression. Plants that overexpressed Ox2 showed phenotypic differences repect to wild type. One phenotypic characteristic was its mayor biomass, therefore we decided to observe cell surface. Almost equal cell size was seen in leaves whose surface were big as twice as wild type. Plants overexpressing both genes were analyzed using IRGA and we saw diferences in chlorophyll fluorescence, A (net photosynthesis) and E (transpiration rate) parameters. The latter led us to observe transpiration by other means and ABA response. A differential response against ABA was evident in plates containing 2% glucose and 0,2M ABA. Another characteristic of these plants was their higher ROS levels in particular leaves. Peroxidation levels, quantified by MDA, were higher in these plants. We suspected that higher ROS levels may difficult pathogens infections. Three days post infection with Pseudomonas psyringae these plants showed, at least four fold less UFC/mg fresh weight than wild type.