SURF-1 modulates hypocotyl growth by influencing auxin and gibberellin action in Arabidopsis

GRAS DE; GONZÁLEZ DH

Cordoba

Congreso; LII Reunión Anual SAIB 2016; 2016

Cytochromec oxidase (COX) biogenesis is a complex process that requires the actionof multiple factors including SURF1 proteins. SURF1 deficiency is amitochondrial disorder and is the most frequent cause of Leigh syndromeassociated with COX deficiency in humans. The role of SURF1 in plants stillremains unknown. SURF1 is encoded by two genes, SURF1-1 and SURF1-2,in Arabidopsis. Heterozygote surf1-1 mutant plants produce 25%abnormal seeds, showing that SURF1-1 is essential for plant development.surf1-2  mutants exhibit shorterhypocotyls under low light intensity compared with those of wild-type plants.In contrast, SURF1-2 overexpressing plants have elongated hypocotylsunder identical conditions. Histochemical analysis using SURF1-2promoter GUS fusions showed that expression levels increase in elongatinghypocotyls. We found that genes encoding auxin and gibberellin (GA)biosynthesis enzymes are significantly repressed in surf1-2 when grown atlow light. Activity of the auxin reporter DR5-GUS was lower in the surf1-2background, indicating reduced auxin response in surf1-2 hypocotyls. Interestingly,normal elongation of surf1-2 hypocotyls was observed in the presence ofexogenous GA and auxin. Our results suggest that SURF1-2 is capable ofregulating the elongation of Arabidopsis hypocotyls acting on GA andauxin homeostasis.