PDF(Pubmed)
Abstract：
MYBs constitute the second largest transcription factor (TF) superfamily in flowering plants with substantial structural and functional diversity, which have been brought into focus because they affect flower colors by regulating anthocyanin biosynthesis. Up to now, the genomic data of several Chrysanthemum species have been released, which provides us with abundant genomic resources for revealing the evolution of the MYB gene family in Chrysanthemum species. In the present study, comparative analyses of the MYB gene family in six representative species, including C. lavandulifolium, C. seticuspe, C. ×morifolium, Helianthus annuus, Lactuca sativa, and Arabidopsis thaliana, were performed. A total of 1104 MYBs, which were classified into four subfamilies and 35 lineages, were identified in the three Chrysanthemum species (C. lavandulifolium, C. seticuspe, and C. ×morifolium). We found that whole-genome duplication and tandem duplication are the main duplication mechanisms that drove the occurrence of duplicates in CmMYBs (particularly in the R2R3-MYB subfamily) during the evolution of the cultivated chrysanthemums. Sequence structure and selective pressure analyses of the MYB gene family revealed that some of R2R3-MYBs were subjected to positive selection, which are mostly located on the distal telomere segments of the chromosomes and contain motifs 7 and 8. In addition, the gene expression analysis of CmMYBs in different organs and at various capitulum developmental stages of C. ×morifolium indicated that CmMYBS2, CmMYB96, and CmMYB109 might be the negative regulators for anthocyanin biosynthesis. Our results provide the phylogenetic context for research on the genetic and functional evolution of the MYB gene family in Chrysanthemum species and deepen our understanding of the regulatory mechanism of MYB TFs on the flower color of C. ×morifolium.
摘要：
MYB构成了开花植物中第二大转录因子（TF）超家族，具有大量的结构和功能多样性。由于它们通过调节花青素的生物合成来影响花朵的颜色，因此受到了关注。到目前为止,几种菊花物种的基因组数据已经发布，这为揭示菊花MYB基因家族的进化提供了丰富的基因组资源。在本研究中,六个代表性物种的MYB基因家族的比较分析，包括Lavandulifolium,C.Seticuspe,C.×morifolium，向日葵，Lactucasativa,和拟南芥，被执行了。总共1104MYB，分为四个亚科和35个谱系，在三种菊花物种中鉴定出(C.lavandulifolium,C.Seticuspe,和C.×morifolium）。我们发现，在栽培菊花的进化过程中，全基因组复制和串联复制是导致CmMYB（尤其是R2R3-MYB亚家族）重复发生的主要复制机制。MYB基因家族的序列结构和选择压力分析表明，某些R2R3-MYB进行了阳性选择，它们主要位于染色体的远端端粒片段上，并包含基序7和8。此外,CmMYBs在C.×moorifolium的不同器官和各个小头发育阶段的基因表达分析表明，CmMYBS2，CmMYB96和CmMYB109可能是花青素生物合成的负调节因子。我们的研究结果为菊花MYB基因家族的遗传和功能进化研究提供了系统环境，并加深了我们对MYBTFs对菊花花色的调控机制的理解。
