Identification,Evolution Analysis And Structure Characterization Of Oil-Regulating Genes ABSCISIC ACID INSENSITIVE3,FUSCA3 And LEAFY COTYLEDON2 In Plants

ABSCISIC ACID INSENSITIVE3(ABI3),FUSCA3(FUS3)and LEAFY COTYLEDON2(LEC2),as plant specific transcription factors,are members of the B3 superfamily.They are named as the master regulators of plant embryo development.They not only play an important role in the growth and maturation of seeds,but also in the lipid metabolism process.Although the functions of these three transcription factors have been identified in some plants,their evolutionary,structural and expressional features in plants have not been studied systematically.In this study ABI3,FUS3 and LEC2,as well as ABI3-like which is unique to algae,were identified by bioinformatics methods in 64 sequenced plants previously.Their origin,distribution,evolution,duplication,functional domains,physicochemical properties,cis-acting elements and gene expression features were analyzed.These results will provide helpful information for further understanding of the functions of ABI3,FUS3 and LEC2 genes in plants,as well as the regulations of plant growth and fatty acid biosynthesis.The main results of this study are as follows:1.Identification of ABI3,FUS3 and LEC2 genes in 64 plants: Two ABI3-like genes were identified in algae,and 76 ABI3 genes were identified in terrestrial plants.However,the FUS3 gene was not identified in the algae and the lower plants,and only 50 FUS3 genes were identified in angiosperms,and only 16 LEC2 gene was identified in dicots.These results indicated that the ABI3 gene exists in most plants,the FUS3 gene exists in Angiosperm,and the LEC2 gene present in dicots.2.Phylogenetic analysis of plants ABI3,FUS3 and LEC2 showed that ABI3 s were divided into three groups,including ABI3-likes of algae,ABI3 s of lower plants and ABI3 s of higher plants;FUS3s were divided into 2 groups,including FUS3 s of monocots and FUS3 s of dicots;LEC2s in dicots were in one group.3.The causes of ABI3 gene duplication in plants are tandem duplication and segmental duplication.The reason for the duplication of the FUS3 and LEC2 genes in plants is mainly segmental duplication.4.The 0,0,2,1,0 is the main intron phase of the plant ABI3 genes and the LEC2 genes.The 0,0,2,1,0 is the main intron phase of the plant FUS3 genes,while very similar intron phases,such as 0,0,0,2,1,0 and 0,0,2,1,were also found in some FUS3 genes.During the evolution of plant ABI3 from algae to higher plants,the motifs are increasing.The number of motifs of FUS3 in dicots is higher than that of monocots.The motifs of LEC2 in the cruciferous are more than others in dicotyledonous.5.During the evolution of plant ABI3,the molecular masses of ABI3 proteins have been increased,and the number of acidic proteins gradually increased.During the evolution of plant FUS3,the protein physicochemical properties of FUS3 are gradually stabilized,and the all FUS3 proteins are acidic proteins in dicotyledonous plants.Most of the LEC2 proteins in dicots are acidic proteins.6.During the evolution process,the cis-acting elements of ABI3 and FUS3 genes are increasing for the adaptation to the environment,and specific cis-acting elements appeared in some plants.A large number of cis-acting elements,closely related to environmental factors,have been evolved in the upstream of LEC2 genes.7.According to the analysis of the cis-acting elements upstream of the gene,it was verified in Chlamydomonas reinhardtii that the light conditions and anaerobic conditions could promote the expression of ABI3-like gene in C.reinhardtii.And oil is accumulated and the expression of ABI3-like gene is increased under nitrogen deficiency conditions.8.In oil crops Glycine max and Brassica rapa ABI3 is mainly expressed in seeds and fruits,and it is hardly expressed in other tissues,indicating that ABI3 gene is closely related to plant oil metabolism.In addition,the FUS3 and LEC2 of Glycine max and Brassica rapa are also mainly expressed in seeds and fruits,and it is also closely related to the oil metabolism of plants.It is also found that t the expression level of ABI3 in the green cotyledons of Amaranthus hypochondriacuswas significantly higher than that in seeds.The expression level of FUS3 gene in green cotyledon of Mimulus guttatus was also significantly higher than that in seeds.This suggests that the ABI3 gene and the FUS3 gene not only express in the seeds and fruits of plants,but also may play an important unknown function in other tissues.