Abstract Pollination and fertilization are key reproductive processes that affects the seed setting of plants. MYB (v-myb avian myeloblastosis viral oncogene homolog) transcription factor is one of the important transcription factor families involved in the regulation of these processes. An unigene sequence sharing high homology with MYB family gene was obtained from gynoecium transcriptome database of previously constructed tree peony (Paeonia ostii 'Feng Dan Bai') and a complete coding region gene named as PoMYB1 (GenBank No. MT360920) was cloned with the expressed sequence tag and rapid amplification of cDNA ends (RACE) methods. PoMYB1 contained a 864 bp long ORF, indicating that it could encode 267 amino acids residues with 2 typical MYB domains. Bioinformatics analysis showed that the molecular formula of PoMYB1 protein was C1434H2235N415O441S12, the relative molecular weight was 32.73 kD and the isoelectric point was 7.01, the fat coefficient was 68.99, and the instability coefficient was 48.18. These characteristics showed that it was an unstable protein. Amino acids alignment revealed that PoMYB1 was composed of highly conserved and incompletely duplicated R2R3-MYB domains. PoMYB1 had 3 characteristic conserved motifs. Phylogenic analysis showed that the PoMYB1 shared the highest similarity with that of PqMYB, followed by MrMYB1, which were obtained from P. qiui and Morella rubra, both belonged to R2R3-MYB transcription factor family of subgroup 6. The expression characteristics of PoMYB1 gene were analyzed by qRT-PCR. The results indicated that the highest in sepal and followed by leaf and petal, which showed that it played a role in the development of flowers and leaves. The highest expressed increment appeared in 24 h after fertilization, and the highest abundance in 48 h after fertilization was observed, which speculated its putative function in double fertilization. Besides, construction of yeast (Saccharomyces cerevisiae) recombinant vectors containing 3 different missing fragments of PoMYB1 and introduced into yeast cells and the transactivation activation activity of PoMYB1 was also verified by yeast one hybrid. The results indicated that PoMYB1 was a transcriptional activator, and the transcriptional regulatory regions in the C-terminus. The study provides theoretical basis for exploring the molecular mechanisms underlying double fertilization in P. ostii and establishes a foundation for further research transcriptional regulation mechanism of PoMYB1.
LIU Peng,LI Wei,XU Zhuang-Zhuang, et al. Analysis of Transactivation Activity and Expression Characteristics of PoMYB1 in Paeonia ostii 'Feng Dan Bai'[J]. 农业生物技术学报, 2020, 28(10): 1798-1809.
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