arabidopsis klu homologue gmcyp78a72 regulates seed size in soybean soybean glycine max is one of the most important crops in the world and its yield is largely determined by grain weight and grain size however the genes that regulate soybean seed size have not been identified cyp78a which is highly conserved within terrestrial plants regulates organ development in arabidopsis atcyp78a5klu has been shown to determine seed size in the present study soybean cyp78a72 gmcyp78a72 one of the orthologs of klu was overexpressed in both arabidopsis and soybean to examine its function in plant development gmcyp78a72 heterologous expression in arabidopsis resulted in enlarged sepals petals seeds and carpel overexpression of gmcyp78a72 in soybean resulted in increased pea size which is an extremely desirable trait for enhancing productivity moreover knockdown of gmcyp78a72 does not reduce grain size however silencing of gmcyp78a57 gmcyp78a70 and gmcyp78a72 genes in triplet reduces the seed size significantly indicating functional redundancy of these three gmcyp78a genes in conclusion we investigated the role of cyp78a in soybean seed regulation and our strategy can be effectively used to engineer large seed traits in soybean varieties as well as other crops