Function Analysis Of RhPILS1,an Auxin Carrier Gene,in Floral Organogenesis In Rosa Hybrida

Roses are one of the most economic valuable ormamental plants,which are widely used as garden ornamental plants,cut flowers,potted flowers,and for the production of essential oils for the cosmetic industries.As the main ornamental part in a flower,the number and arrangement of petals affect floral form,which has the basic ornamental value.Auxin,as the main regulator in the growth and development of plants,plays a key role in floral organogenesis.Auxin efflux carrier PILS proteins are required for auxin-dependent regulation of plant growth and organ formation.Here,we investigated the role and the molecular mechanisms of PILS in regulating the floral organogenesis in Rose.Here,we divided early flower development into five distinct phases ranging from the setting of the sepal primordium to the completion of the flower differentiation by morphometric analysis.According to the "five rose flower transcriptomes",we found numerous PILS assemble transcripts,which are from 6 RhPILS based on sequence aligment.One of which "RU10743" shows different expression pattern and is the most abundant PILS confirmed by RT-qPCR.We obtained the full-length of RU10743 and named it as RhPILS1.To investigate the role of RhPILS1 in rose flower organogenesis,we developed a VIGS system by tissue-cultured plants,which has 40%gene silencing efficiency and is suitable for genes involved in floral developmet.Through VIGS in rose plants,we found that RhPILS1-silencing significantly reduced the number of petals and increased the number of stamens,while the total number of petals and stamen was not significantly changed.The VIGS of RhPILS1 showed its role in the homeotic transformation between petals and stamens.Free IAA level of silenced flowers is significantly down regulated and the expression level of auxin responsive genes such as ARFs and AUX/IAA were significantly changed in RhPILS1 silenced flowers.Moreover,expression level of RhAG was significantly up-regulated in RhPILS1 silenced petals.There was cis-element binded by auxin responsive gene in the RhAG promoter according to PLACE analysis,which suggested the transcriptional regulation of RhAG by auxin responsive genes.In conclusion,RhPILS1 regulated the floral development in rose.RhPILS1 modulated free IAA level and auxin signaling during the floral organogenesis.RhPILS1 played a role in the homeotic transformation between petals and stamens by regulating the expression of RhAG,which may be by auxin responsive dependent way.However,which and how auxin responsive gene regulated by RhPILS1 control the transcription of RhAG still need to be studied.