Brassinosteroid（BR）andgibberellin（GA）aretwopredominantplanthormonesthatregulateplantcellelongation.Mutantsdisruptthebiosynthesisofthesehormonesanddisplaydifferentdegreesofdwarfphenotypesinrice.Althoughtheroleofeachplanthormoneinpromotingthelongitudinalgrowthofplantshasbeenextensivelystudiedusinggeneticmethods,theirrelationshipisstillpoorlyunderstood.Inthisstudy,weusedtwospecificinhibitorstargetingBRandGAbiosynthesistoinvestigatetherolesofBRandGAingrowthofriceseedlings.Yucaizol,aspecificinhibitorofBRbiosynthesis,andTrinexapac-ethyl,acommerciallyavailableinhibitorofGAbiosynthesis,wereused.TheeffectofYucaizolonriceseedlingsindicatedthatYucaizolsignificantlyretardedstemelongation.TheIC50valuewasfoundtobeapproximately0.8μmol/L.Yucaizolalsoinducedsmallleafanglephenocopyinriceseedlings,similarlytoBR-deficientrice,whileTrinexapac-ethyldidnot.WhenYucaizolcombinedwithTrinexapac-ethylwasappliedtothericeplants,themixtureofthesetwoinhibitorsretardedstemelongationofriceatlowerdoses.OurresultssuggestthattheuseofaBRbiosynthesisinhibitorcombinedwithaGAbiosynthesisinhibitormaybeusefulinthedevelopmentofnewtechnologiesforcontrollingriceplantheight.
