Cloning And Expression Patern Analysis Of B-function And C-function MADS-box Genes In Lagerstroemia Speciosa

Lagerstroemia speciosa belongs to the Lythraceae family,and it is a famous popular woody ornamental plant.L.speciosa have long-lasting summer bloom,rich colors and abundant flowers.To our knowledge,there is no double flower in Lagerstroemia.We discovered a double-flower mutant of L.speciosa which was extreamLy rare.Therefore,the double-flower L.speciosa is an ideal material for the study of the formation and origin of double flower in Lagerstroemia.According to the floral organ development ABC model,B and C class genes specify petal and stamen identification.Real time quantitative PCR technique was used to study the gene expression pattern.In order to ensure the accuracy of quantification,we also selected a number of candidate genes suitable for the study of the development of flower.The main conclusions are as follows:1.Four MADS-box genes were obtained from L.speciosa,including two B class genes(LsDEF1 and LsPI1),and two C class genes(LsAG1 and LsAG2).Sequence analysis showed that genes were diverse from single-flowered to double flowered L.speciosa,and the mutation and deletion of the base resulted in the change of gene structure,which may be related to the fonnation of the double flower.2.In this study,we evaluated the expression stability of 9 candidate reference genes(GAPDH,TUA,TUB,18S,RP?,EF-1-?,ATC,EIF5A and CYP)in four different tissues and four flower developmental stages of L.speciosa by four algorithms.We found that RP? and EF-1? were nost stably expressed,which were suitable reference genes for L.speciosa.3.The gene expression patterns of LsDEF1,LsPI1,LsAGl and LsAG2 in single-flowered and double-flowered L.speciosa were analyzed.The expression of the LsDEF1 and LsPI1 was restrained at the late stage while LsAG1 and LsAG2 showed an extremly high expression at the early stage of floral development.Extend expression of LsDEF1 and LsPI1 in the fourth cricle of the floral organ(pistil)were observed,so did the LsAG2 which were in the second cricle of the floral organ(petals).These may be the important factors which cause the double-flowered mutant of L.speciosa.The results showed that the B-class and C-class genes play key roles in the floral development of L.speciosa,and provide a theoretical basis for further research to change floral organ structures and create new materials for plant breeding.