Study On The Expression And Protein-Protein Interaction Betweenrice Coiled Coil Domain Containingosmy1, OsMY2and OsRac5

ROP is the sole family of small GTP-binding protein in plants. It plays an important role in polargrowth, development and responses to enviroment.Taking rice ROP OsRac5as bait, two putative partnersencoding genes OsMY1and OsMY2were isolated from the rice panicle cDNA library by yeast two-hybridscreening.Sequence analysis showed that OsMY1and OsMY2shared14%and49%of nucleotide and aminoacid sequence similarity, respectively, and both contain entirely coiled-coil （CC） domains.Phylogeneticanalysis showed that OsMY1has a close genetic relationship with Brachypodium constitutive activationROP1interacting proteins （XP₀03569847）, OsMY2has a close genetic relationship with a RiceNipponbare constitutive activation ROP1interacting proteins （CAD89536）.The results of quantitativereal-time PCR revealed that OsMY1and OsMY2expressed in roots, stems, and leaves of rice at differentdevelopmental stages,especially in panicle. The expressions of OsMY1and OsMY2were up-regulated byphytohormones and abiotic stresses, such as IAA, ABA, GA, drought, cold, salt, in rice seedlings, while nosignificant effects were observed in the treatments of BR,SA and6-BA. OsMY1and OsMY2are expressedubiquitously in the examined rice leaves and panicle, but more abundant in panicles, with similar changetrend compared with OsRac5, showed that suggesting they may function at both vegetative andreproductive stages in the same regulatory pathway. OsMY1,OsMY2and OsRac5expressed in leaves ofrice at different developmental stages,especially in panicle,The expression pattern of certain correlation,suggesting that There is an important contact at the transcriptional level.By yeast two-hybrid assay, it were confirmed that OsMY1and OsMY2bind both the wild type andconstitutively active OsRac5, but does not interact with dominantly negative OsRac5, suggesting that the interaction between them were independent with whether OsRac5activation or not. Then the interactionbetween OsMY1，OsMY2and OsRac5, which in wild type and constitutively active state, were verifiedin the cytoplasm of onion epithelial cell by BiFC assay.This study confirms the authenticity of the the interaction between OsMY1, OsMY2withOsRac5.Our study confirmed OsMY1and OsMY2are important interaction protein of OsRac5, by meansof evolutionary conservative binding, OsMY1and OsMY2may be the important intermediary moleculesto correlate Rho with actin cytoskeleton.These results may be helpful to study the functions ofOsMY1,OsMY2and OsRac5in rice growth, development, and responses to phytohormones and abioticstresses in the future.and Laid the foundation for the study of the functional linkages and mechanism of theinteractions between OsMY1,OsMY2and OsRac5.