Functional Analysis Of Hd1,Hd3a And OsFD1 Gene In Defence Response

In rice,Hd3 a,14-3-3 and OsFD1 proteins,forming florigen activation complex,are key components in flowering time regulation.14-3-3 genes in rice response to biotic and abiotic stress has also been well addressed.The role of 14-3-3e in rice defense has been well studied.However,whether Hd1,Hd3 a and OsFD1 play roles in rice defense is still unclear.In present study,we identified that Hd1,Hd3 a and OsFD1 expression was repressed by Xanthomonas oryzae pv.oryzae(Xoo)and jasmonic acid(JA),and validated that Hd1,Hd3 a and OsFD1 negatively regulated rice resistance to Xoo and Xanthomonas oryzae pv.oryzicola(Xoc).hd1,hd3 a and osfd1 mutants increased resistance to both Xoo and Xoc,and activated JA responsive gene OsJAZ8 and JA synthetic enzyme gene AOS2 expression.Our data also demonstrated that OsFD1 binds to the promoters of and activated the expression of OsJAZ2 and OsJAZ9 genes;Hd3a,cooperating with 14-3-3e,promoted OsFD1 action on OsJAZ2 gene expression.hd3 a and osfd1 mutants accumulated less OsJAZ2 and OsJAZ9 transcripts.These data suggested that Hd3 a and OsFD1 negatively regulated rice defense by activating OsJAZ2 and OsJAZ9 expression in JA-related signaling.