Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Plant Protection submitted time 2018-07-18 Cooperative journals: 《广西植物》
Abstract： Anthocyanin-rich purple sweet potatos have high edible and medicinal value. Anthocyanin biosynthesis is controlled by structural genes and regulatory genes. The bHLH (basic helix-loop-helix protein) transcription factor plays an important role in anthocyanin biosynthesis by regulating multiple structural genes. However, there are no reports about bHLH regulating anthocyanin biosynthesis in sweet potato. In this study, a bHLH gene named IbGL3 was cloned in Ipomoea batatas based on transcriptome data and RT-PCR technology. The full-length cDNA of IbGL3 was 2 120 bp, containing 1 878 bp opening reading frame (ORF), and encoding 625 amino acids. The encoded protein of IbGL3 has a molecular weight of 69.08 kD and the theoretical isoelectric point (pI) of 5.20. The IbGL3 protein was classified as unstable protein instability with index of instability index 43.06, and belonged to hydrophilic protein with grand average of hydropathicity of -0.555. Subcellular localization prediction showed that IbGL3 was most likely to be located in the nucleus, and the nuclear localization signal (PSSKKRKASKT) was located at the C-terminal. Signal peptide analysis showed that IbGL3 protein had no signal peptide and was not a secretory protein. Transmembrane domain analysis showed that IbGL3 protein had no transmembrane domain. The IbGL3 protein had highly conserved MIR motif, bHLH domain and ACT domain, shared high identities and similar domains with bHLH proteins involved in anthocyanin biosynthesis from other plants. Phylogenetic analysis showed that and IbGL3 was clustered in the IIIf bHLH subgroup together with other anthocyanin-related bHLH proteins. The expression of IbGL3 in the storage root of different sweet potato varieties was detected by quantitative polymerase chain reaction (qPCR). The results indicated that IbGL3 was mainly expressed in purple-fleshed sweet potato, followed by light purple-fleshed sweet potato and weakly expressed in white-fleshed sweet potato, and its expression was positively related to the accumulation of anthocyanin Ipomoea batatas. The results showed IbGL3 may be involved in regulating anthocyanin biosynthesis in Ipomoea batatas. The results will provide assistance and guidance to further understand the function and molecular mechanism of IbGL3 in the biosynthesis of anthocyanins in sweet potato, and lay the foundation for genetic improvement of anthocyanin in sweet potato.
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