Map-based Cloning And Functional Analysis Of An Auxin-related Gene G46in Arabidopsis

Auxin is an essential phytohormone, which plays critical roles in many plantgrowth and development processes. Auxin functions at three levels: auxin biosynthesis,auxin polar transport and signal transduction. In the last three decades, scientists tookbiochemical and molecular genetic approaches to study the mechanisms of its action, andmade great progress. However, it is still not clear how auxin regulates plant development.We carried out a genetic screen to isolate new components in auxin pathways. We firstmutagenized Arabidopsis npy5pid double mutant using EMS. We isolated a mutant g46,which produces pin-like inflorescence in npy5pid double mutant background. Usingmap-based cloning method, we cloned the G46gene, and found it is an new allele ofCYP79F1.g46single mutants shows pleiotropic developmental defects: curved blade, vasculargrowth retardation, bushy, and low fertility, but its embryogenesis seems normal. Becauseauxin plays an important role in control of leaf morphology and apical dominance, wehypothesized that the auxin concentration has altered in g46. To test this, we introduced theauxin response reportor DR5:GUS into g46mutant background. We found that of theexpression levels of DR5:GUS in cotyledons of g46single mutan were remarkablelyincreased. Inactivation of the G46gene in the pid mutant background, led to completelypin-like inflorescence, and shortened inflorescence rachis, while neither pid nor g46singlemutant showed such phenotypes. These findings suggest genetic interactions between PIDand G46. on the other hand, we did not observed obvious changes of the expression levelsand subcellular localization of the PIN1protein in g46single mutant. Taken together, thesefindings suggest that G46/CYP79F1may regulate auxin homeostasis or signal transductionto control plant development.