Genetic Diversity Of Flowering Related Genes Among Citrus Species

The citrus plant can be easily hybridized between species and display different types on flowering babits. FT, LFY, TFL1, SOC1 and FLC are important key genes participating in flowering regulation in plants. This paper aims to reveal genetic diversity of flowering related genes and its relationship to evolution of citrus species, as well to understand the mechanism of flowering transition and character formation. Pairs of primers were designed according to Clementina genome in Phytozome v9.1. Fragments of genes were cloned in 11 species of Citrus, such as precocious trifoliate orange, trifoliate orange, kumquat, navel orange and lemon, etc.. The main results are as follows:1. Diversity analysis of FT gene:The nucleotide similarity, amino acid similarity and promoter sequence similarity of eleven species was respectively 98.29%,98.31%, 95.12%; Thitrty-four mutation loci of single nucleotide polymorphism were discovered in full length nucleotide sequence, twenty-nine in untranslated region and five in translated region, which resulted in three amino acid changes. Accoring to the calculation results, the polymorphism frequence was 1SNP/64bp, the variation percentage of nucleotides and amino acids were 1.709% and 1.695% respectively. Sixty-eight mutation loci of single nucleotide polymorphism were discovered in promoter sequence, the polymorphism frequence was 1SNP/22bp; According to the phylogenic analysis in nucleotide sequence, we found that Precocious trifoliata and Poncirus trifoliata were far away from other species; According to the phylogenic analysis in promoter sequence, we found that Precocious trifoliata and Poncirus trifoliata were far from other species.2. Diversity analysis of LFY gene:The nucleotide similarity, amino acid similarity and promoter sequence similarity of eleven species was respectively 97.94%,97.74%,98.31%; Forty-three mutation loci of single nucleotide polymorphism were discovered in full length nucleotide sequence, twenty in untranslated region and twenty-three in translated region, which resulted in nine amino acid changes. Accoring to the calculation results, the polymorphism frequence was 1SNP/49bp, the nucleotide and amino acid degree of the variation of nucleotide and amino acids were 2.055% and 2.261%. Twenty-eight mutation loci of single nucleotide polymorphism were discovered in promoter sequence, the polymorphism frequence was 1SNP/61bp; According to the phylogenic analysis in nucleotide sequence, we found that Citrus limon, Citrus madica and Citrus ichangensis were far away from other species; According to the phylogenic analysis in promoter sequence, we found that Precocious trifoliata and Poncirus trifoliata were far from other species.3. Diversity analysis of TFL1 gene:The nucleotide similarity, amino acid similarity and promoter sequence similarity of eleven species was respectively 98.63%,98.84%,97.91%; Eighteen mutation loci of single nucleotide polymorphism were discovered in full length nucleotide sequence, twelve in untranslated region and six in translated region, which resulted in two amino acid changes. Accoring to the calculation results, the polymorphism frequence was 1SNP/81bp, the nucleotide and amino acid degree of the variation of nucleotide and amino acids were 1.369% and 1.156%. Twenty-four mutation loci of single nucleotide polymorphism were discovered in promoter sequence, the polymorphism frequence was 1SNP/54bp; According to the phylogenic analysis in nucleotide sequence, we found that Precocious trifoliata and Poncirus trifoliata were far away from other species; According to the phylogenic analysis in promoter sequence, we found that Precocious trifoliata and Poncirus trifoliata were far from other species.4、Diversity analysis of SOC1 gene:The nucleotide similarity, amino acid similarity and promoter sequence similarity of eleven species was respectively 95.17%,96.82%,96.75%; Two hundreds and fifty mutation loci of single nucleotide polymorphism were discovered in full length nucleotide sequence, two hundreds and thirty-three in untranslated region and seventeen in translated region, which resulted in seven amino acid changes. Accoring to the calculation results, the polymorphism frequence was 1SNP/21 bp, the nucleotide and amino acid degree of the variation of nucleotide and amino acids were 4.829% and 3.182%. Thirty-one mutation loci of single nucleotides were discovered in promoter sequence, the polymorphism frequence was 1SNP/31bp; According to the phylogenic analysis in nucleotide sequence, we found that Precocious trifoliata and Poncirus trifoliata were far away from other species; According to the phylogenic analysis in promoter sequence, we found that Precocious trifoliata and Poncirus trifoliata were far from other species.5、Diversity analysis of FLC gene:The nucleotide similarity of 6 species was higher than 97%; According to the phylogenic analysis in first intron sequence, we found that Precocious trifoliata and Poncirus trifoliata were far from other species.Considering all the gene above, we could make a conclution that Poncirus was far different from Citrus and Fortunella, Fortunella and Citrus had transmutation in flowering related genes.