Molecular Dissection Of Arabidopsis AP2/ERF Family Gene ERF055in Regulation Of The Development Of The Shoot Apical Meristem

AP2(APETALA2) and EREBP (ethylene-responsive element binding proteins) are themembers of a family of transcription factors unique to plants whose distinguishingcharacteristic is that they contain the so-called AP2DNA-binding domain that usuallyconsists of60-70amino acid residues. AP2/ERF genes form a large multigene family thatincludes ERF family, AP2family and RAV family. They play a variety of roles throughout theplant life cycle: from being key regulators of several growth and developmental processes likeinflorescence meristem and leaf peridermal cell identity determination, floral development orembryogenesis to forming part of the mechanisms used by plants to respond to various typesof biotic and environmental stress.ERF055gene is a member that belongs to the AP2/ERF super gene family, ERF familyand DREB family. Postembryonic organ formation in higher plants relies on the activity ofstem cell niches in shoot and root meristems where differentiation of the resident cells isrepressed by signals from surrounding cells. People searched for mutations affecting stem cellmaintenance and isolated the semidominant l28mutant, which displays premature terminationof the shoot meristem and differentiation of the stem cells. Allele competition experimentssuggest that l28is a dominant-negative allele of the gene of AP2family, which previously hasbeen implicated in floral patterning and seed development. Genetic analysis shows that thatAP2functions in stem cell maintenance by modifying the WUS-CLV3feedback loop.Now, the research of the gene function has not been reported. However, with thedevelopment of the seed, the expression level of the ERF055gene increases gradually, and itgets the highest level in the mature seeds. It suggests that the gene may be related to thedehydration and development of the seed.Is it involved in the regulation of embryonic development? What is the effect ofmolecular dissection in regulation of the development of the shoot apical meristem? Now, weuse the technologies of genetics, molecular biology and anatomy in order to study the roles ofthe ERF055gene in the process of embryonic development and regulation functions of theshoot apical meristem development. Also, the results can provide new data in the aspect ofmolecular dissection of Arabidopsis AP2/ERF supergene family in regulation of the development of the shoot apical meristem.The function of AP2/ERF gene family is diverse, including plant nutrition and regulationof growth and development. In this study, we screened69mutants of42AP2family genesand3of them had phenotype in embryonic development. The erf055mutant was chosen forfurther functional identification. In the erf055mutant, the retardation of the development ofzygotic embryo was observed. We also compared the developmental process of zygoticembryo in WT and overexpressing lines. We also anyalyzed the tissue specific expression andthe expression pattern in the development of zygotic embryo of ERF055.（1）Phylogenetic analysis showed that ERF055had many paralogs with high sequencesimilarity, which might be functional redundant.（2）In the embryo developing stage, the developmental process in the heart satge andtorpedo stage was increased in plants overexpressing ERF055compared with WT, and in thematuration stage, the precess was similar, while in the postembryo development stage, theSAM of plants overexpressing ERF055was smaller than that in WT, and the leaf formationwas relatively slower. In the ERF055RNAi lines, the leaves were larger than that in WT.（3）InArabidopsis, ERF055expressed in root, stem, leaf, flower, and silique. In silique,the expression level was highest, indicating that the gene may function in the maturation ofseeds.（4）The ERF055gene functioned in the regulation of both embryo and postembryodevelopment process, as well as the development of shoot apical meristem. By in situhybridation and GUS staining analysis, we observed that ERF055expressed in each stage ofembryo development. In postembryo development, ERF055expressed in SAM, leafprimordium and young leaves in the seedlings. In the2-day-old and3-day-old seedlings,ERF055expressed in the whole embryo, cotyledon, hypocotyl and radicle, with the highestexpression level in maturation zone, while in5-day-old seedlings, ERF055mainly expressedin the root cap, and in7-day-old seedlings, ERF055mainly expressed in lateral rootprimordium.（5）The transient expressing assay in tobacco showed that ERF055encoded atranscription factor, which played important roles in plant growth and development.