[Objective]Allium wallichii is a characteristic alpine flower.Anthocyanidin synthase(ANS)is a key enzyme in the anthocyanin biosynthesis,which lies downstream of flavonoid biosynthesis.This study is to investigate the role of ANS in the flower color formation of purple and white A.wallichii.[Method]pH-differential method was used to determine the total anthocyanin contents at different developmental stage of flowers.The coding sequences of AwANS genes were cloned by RT-PCR.The sequence alignments and expression patterns of AwANSs were also analyzed.[Result]The total anthocyanin contents of purple flowers increased gradually with flower development and peaked at S4,while those of white flowers could barely be measured.Two sequences of AwANS(AwANSpa and AwANSpb)were cloned from white A.wallichii flowers and both of them had the CDS sequence length of 1 074 bp CDS with 357 amino acids.However,there were five sequences of AwANS(AwANSwa,AwANSwb,AwANSwc,AwANSwd,and AwANSwe)cloned from purple A.wallichii flowers.Among them,AwANSwa and AwANSwd were 1 074 bp and 1 077 bp in CDS length,encoding two proteins with 357 and 358 amino acids,respectively.The protein translations of the remaining three sequences were terminated prematurely because of large fragment deletion.Phylogenetic analysis indicated that AwANSs were the closest to A.cepa.qRT-PCR analyses indicated that AwANSs in purple A.wallichii flowers had the highest expressions in blooming flowers and had the lowest expressions in the roots,pistils and fruits.The expression of AwANSs enhanced gradually with flower development and reached the peak at S5 in purple A.wallichii flowers.However,AwANSs expression were almost undetectable in white flowers.[Conclusion]The expressions of AwANSs have obvious spatial and temporal specificity and are the highest in flowers.Compared with purple A.wallichii,anthocyanins could not be detected and AwANSs are barely expressed throughout flower development in white flowers,suggesting AwANSs might play a key role in the flower color formation of purple A.wallichii.
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