谷子 MADS-box基因家族的鉴定和表达分析

MADS-box基因是真核生物中一类重要的转录因子,参与调控多项植物的生长发育过程。然而关于谷子穗发育的MADS-box基因研究比较少。本研究使用序列相似性检索,在Phytozome 13.0数据库中筛选并且鉴定出了68个谷子MADS家族成员,并对这些家族成员的物理化学性质、系统发育树、染色体定位、表达谱等进行了全面的分析。结果表明,谷子MADS家族成员在染色体上分布不均匀,可以分为5个亚族。通过组织特异性表达谱分析得到,多数MADS基因在穗中表达量要高于其他器官。此外利用转录组测序技术对发育初期的谷穗和成熟期的谷穗进行了转录组测序分析,筛选到数个与谷穗分生组织发育相关MADS-box基因。为进一步揭示MADS-box基因在谷子穗发育过程中的作用奠定了重要的基础。     

Genomewide Structural Annotation and Evolutionary Analysis of the Type I MADS-Box Genes in Plants

Abstract The type I MADS-box genes constitute a largely unexplored subfamily of the extensively studied MADS-box gene family, well known for its role in flower development. Genes of the type I MADS-box subfamily possess the characteristic MADS box but are distinguished from type II MADS-box genes by the absence of the keratin-like box. In this in silico study, we have structurally annotated all 47 members of the type I MADS-box gene family in Arabidopsis thaliana and exerted a thorough analysis of the C-terminal regions of the translated proteins. On the basis of conserved motifs in the C-terminal region, we could classify the gene family into three main groups, two of which could be further subdivided. Phylogenetic trees were inferred to study the evolutionary relationships within this large MADS-box gene subfamily. These suggest for plant type I genes a dynamic of evolution that is significantly different from the mode of both animal type I (SRF) and plant type II (MIKC-type) gene phylogeny. The presence of conserved motifs in the majority of these genes, the identification of Oryza sativa MADS-box type I homologues, and the detection of expressed sequence tags for Arabidopsis thaliana and other plant type I genes suggest that these genes are indeed of functional importance to plants. It is therefore even more intriguing that, from an experimental point of view, almost nothing is known about the function of these MADS-box type I genes.     

Chromosomal mapping of the MADS-box multigene family in Zea mays reveals dispersed distribution of allelic genes as well as transposed copies.

A linker PCR procedure has been developed for preparing repetitive DNA-free probes from genomic clones, which is especially efficient for members of gene families. Using this procedure as well as standard methods to prepare hybridization probes, chromosomal map positions of MADS-box genes were determined in recombinant inbred lines of maize (Zea mays ssp. mays). It appears that MADS-box genes are scattered throughout the maize genome. While there is evidence that this genomic distribution is representative for plant MADS-box genes in general, the following two other observations probably reflect Zea genome organization. First, at least one family of MADS-box-carrying elements contains line-specific versions, which are present in some maize lines at certain chromosomal positions, but are absent from these loci in other lines. The members of this family resemble transposable elements in some respects. Secondly, the finding of pairs of highly related MADS-box genes which are accompanied by other duplicated markers is a further indication of the ancestral polyploid genome constitution revealed with other markers. The importance of these findings for an understanding of the genomic organization of MADS-box genes and the evolution of the MADS-box gene family is discussed.