The Preliminary Analyses Of Petal Conical Cell Morphogenesis Regulated By ROP Signaling In Arabidopsis

Most flowering plants have special conical-shaped epidermal cells on the petal surface,the conical cell affects the light reflectance and the ability to capture the light of the flowers,and provides a good standing platform for pollinators,thus improves the pollination rate.However,the molecular mechanism of regulating conical cell morphogenesis is rarely reported.In Arabidopsis thaliana,ROP(Rho of plants)is one of the key components of small G protein signaling,it plays a crucial role in the process of hormone signal transduction,polar growth and stress response as "molecular switch" function.In this project,Arabidopsis thaliana petals were used as experimental material to investigate the functions of the ROP signaling members,ROP,FER(FERONIA),SPK1(SPIKE1),RIC(ROP-interacting CRIB-containing protein)on the conical cell morphogenesis.After the analyses of experimental results,spkl-4,rop2 rop6 ROP4RNAi 14-3(r24i6),Constitutively active rop2(CA ROP2)and relevant transgenic materials showed pointy cotyledon,reduced skeleton(a parameter indicating the complex degree of pavement cells),it suggests that,ROP signaling significantly modulates pavement cell development to control cotyledon shape.Simultaneously,spkl-4,r24i6 14-3 and CA ROP2 exhibited narrower petals and swollen conical cells.which suggests that ROP signaling is also involved in the regulation of conical cells development and petal shapes.The GUS staining assays of SPK1,ROP2 and ROP6 showed that all the three genes expressed in the process of floral organ development,and presented quantity gradient from stage 12 to stage 14.In order to further investigate the mechanism of ROP signaling pathways in regulating the conical cell morphogenesis,cytoskeleton arrangement observation was performed,since it has well known functions in the maintenance of cell shape.This project found that the microtubule orientation of spk1-4,CA ROP2,CA ROP6,RIC1 OE-3 showed extremely disordering,interestingly,the microfilament arrangement displayed no significant changes compared to wild type.Conclusively,this project revealed that ROP signaling not only generally modulates the vegetative growth,but also control the cell development to influence the final organ shapes of flower petals.Initiatively,we found that ROP signaling mainly affect the conical cell morphogenesis through regulating arrangement of microtubules,but not that of microfilament.This project provides a newly progress for elucidating the function of ROP signaling in the conical cell morphogenesis.