Functional Analyses Of APETALA1/FRUITFULL Transcription Factor Subfamily Genes In Brachypodium Distachyon L.

In the history of evolution,the evolution of MADS-box genes has featured numerous duplications and losses,affecting a single species or entire clades of land plants.These transcription factors play key roles in plant development,most notably floral organ identity.It has been speculated that duplications and subsequent diversification of MADS box genes may have been a factor in the evolution of morphological diversity in land plants and of angiosperms in particular.For example,within angiosperms,a cluster of duplications is correlated with the diversification of the core eudicots,a clade that encompasses the vast majority(roughly 75%)of extant flowering plants and that includes major model systems such as Arabidopsis(Arabidopsis thaliana),snapdragon(Antirrhinum majus),and tomato(Solanum lycopersicum).Among the gene lineages affected by this event are key regulators of floral organ identity: APETALA1(AP1,A function),APETALA3(AP3,B function),and AGAMOUS(AG,C function).Comparative functional studies of AP3 and AG orthologs in monocots,basal eudicots,and core eudicots suggest that,fundamentally,the functions of these genes in petal,stamen,and carpel identity were conserved before and after the core eudicot duplication.Brachypodium distachyon L.is proposed as a model for temperate cereals.It possess many advantages as a model species such as a small genome size,a rapid lifecycle,a simple grow condition and self-pollination,and it is closely related to the main crop crops such as wheat and rice.Therefore,the functional research on the gene of Brachypodium distachyon L.is beneficial to us to better understand the genetic function of wheat and other food crops.The AP1/FUL transcription factor subfamily belongs to the family of MADS-box transcription factors,and this subfamily has doubled in the process of plant evolution.In this study,we mainly studied the function of four AP1/FUL subfamily genes from the perspective of mutants.The main results are as follows:(1)In Brachypodium distachyon L.,there are four AP1/FUL subfamily genes BdVRN1,BdFUL2,BdFUL3 and BdFUL4.Which BdFUL4 gene in the evolution of the process losted the main functional area FUL motif,may evolve with the ancestors of different functions.(2)Mutation of the BdVRN1 gene could lead to extremely late flowering phenotypes,indicating that the BdVRN1 gene may play an important role in the regulation of plant flowering time.(3)BdFUL2 gene mutation,could lead to abnormal development of floral organs: the lemma degeneration,the formation of leaf-like tissue,outer floral organs like glumes and lodicule was abnormal,the number of and axillary meristem spike primordium have a certain increase,spikelet elongation developed into a branch-like tissue.These results suggested that the BdFUL2 gene played an important role in flower formation and flower organ development.(4)Analysis of WT and ful2.c1 mutant seeds revealed that the ful2.c1 mutant had more tuberculosis than WT,but the seed size of the ful2.c1 mutant was significantly smaller than that of WT.In order to obtain an increased seeds amount,but not plant inflorescence development abnormalities occur plant,we constructed BdFUL2.RNAi and TaFUL2.RNAi carrier,respectively,intend to convert Brachypodium distachyon L.and wheat,hoping to get more conducive to increase production of food crops phenotype.(5)The BdFUL2 gene may be able to form a quartet model that plays a role in the regulation of outer flower floral organs.It can interact with the E gene,may have the function of class A gene,and itself has a strong interaction,can form homologous dimer,so as to meet the Arabidopsis quartet model control outer flower organ quartet model AP1-AP1-SEP-SEP regulates the development of outer flower organ.However,BdFUL2 gene was able to form a normal flower structure,which may be due to the functional redundancy of the BdFUL2 gene with other AP1/FUL genes such as the BdVRN1 gene.BdVRN1 forms a new quartet model in the late stage to regulate the development of the floral organ.(6)The mutants of the BdFUL3 and BdFUL4 genes did not find any apparent phenotype,possibly that the two genes had functional redundancy in other genes.