(174ag) Characterization and Function Test a Unique MAX1 Homolog from Prunus

Strigolactones (SLs) are a class of carotenoid-derived plant hormones, that can stimulate the germination of parasitic weeds and promote symbiosis with rhizosphere microorganisms arbuscular mycorrhizal fungi (AMF). SLs also play an important to the plant growth and development, such as regulating root architecture. The More Axillary Growth (MAX1) is a key enzyme in SL biosynthesis family, with a conserved function across seed plants converting carlactone (CL) into the key intermediate carlactonoic acid (CLA). Here, we identified a unique MAX1 gene from the Prunus family, PpMAX1c, as a dual-functional MAX1. PpMAX1c directly converts CL into strigol and an unidentified isomer, which is isolated and structurally identified. Through a structure-guided mutational study, we pinpointed the key residues in PpMAX1 that are essential for synthesizing either strigol or the isomer. Our biochemical characterization revealed the enzymatic mechanism of PpMAX1 being dual functional and able to catalyze oxidation at three different carbons. Furthermore, we are conducting functional validation of PpMAX1c in Arabidopsis to investigate the evolutionary mechanism underlying its dual functionality as an enzyme.