Institute of Agrobiotechnology (INA), CERTH, Thermi-Thessaloniki, GR-57001, Greece.
BMC Plant Biol. 2012 Sep 17;12:166. doi: 10.1186/1471-2229-12-166.
MADS-box genes constitute a large family of transcription factors functioning as key regulators of many processes during plant vegetative and reproductive development. Type II MADS-box genes have been intensively investigated and are mostly involved in vegetative and flowering development. A growing number of studies of Type I MADS-box genes in Arabidopsis, have assigned crucial roles for these genes in gamete and seed development and have demonstrated that a number of Type I MADS-box genes are epigenetically regulated by DNA methylation and histone modifications. However, reports on agronomically important cereals such as barley and wheat are scarce.
Here we report the identification and characterization of two Type I-like MADS-box genes, from barley (Hordeum vulgare), a monocot cereal crop of high agronomic importance. Protein sequence and phylogenetic analysis showed that the putative proteins are related to Type I MADS-box proteins, and classified them in a distinct cereal clade. Significant differences in gene expression among seed developmental stages and between barley cultivars with varying seed size were revealed for both genes. One of these genes was shown to be induced by the seed development- and stress-related hormones ABA and JA whereas in situ hybridizations localized the other gene to specific endosperm sub-compartments. The genomic organization of the latter has high conservation with the cereal Type I-like MADS-box homologues and the chromosomal position of both genes is close to markers associated with seed quality traits. DNA methylation differences are present in the upstream and downstream regulatory regions of the barley Type I-like MADS-box genes in two different developmental stages and in response to ABA treatment which may be associated with gene expression differences.
Two barley MADS-box genes were studied that are related to Type I MADS-box genes. Differential expression in different seed developmental stages as well as in barley cultivars with different seed size was evidenced for both genes. The two barley Type I MADS-box genes were found to be induced by ABA and JA. DNA methylation differences in different seed developmental stages and after exogenous application of ABA is suggestive of epigenetic regulation of gene expression. The study of barley Type I-like MADS-box genes extends our investigations of gene regulation during endosperm and seed development in a monocot crop like barley.
MADS-box 基因构成了一个庞大的转录因子家族，在植物营养和生殖发育过程中起着关键的调控作用。II 型 MADS-box 基因已得到深入研究，主要参与营养和开花发育。越来越多的拟南芥 I 型 MADS-box 基因的研究表明，这些基因在配子和种子发育中起着至关重要的作用，并证明了许多 I 型 MADS-box 基因受 DNA 甲基化和组蛋白修饰的表观遗传调控。然而，关于大麦和小麦等农业上重要的禾本科作物的报道却很少。
本文从大麦（Hordeum vulgare）中鉴定和描述了两个 I 型类似的 MADS-box 基因，大麦是一种具有重要农业意义的单子叶禾本科作物。蛋白序列和系统发育分析表明，这些推测的蛋白与 I 型 MADS-box 蛋白相关，并将它们归类于一个独特的禾本科分支。这两个基因在种子发育阶段和种子大小不同的大麦品种之间的基因表达存在显著差异。其中一个基因受种子发育和应激相关激素 ABA 和 JA 的诱导，而另一个基因通过原位杂交定位于特定的胚乳亚区。后者的基因组组织与禾本科 I 型类似 MADS-box 同源物高度保守，并且两个基因在染色体上的位置接近与种子质量性状相关的标记。在两个不同的发育阶段和 ABA 处理后，在大麦 I 型类似 MADS-box 基因的上游和下游调控区存在 DNA 甲基化差异，这可能与基因表达差异有关。
本文研究了两个与 I 型 MADS-box 基因相关的大麦 MADS-box 基因。这两个基因在不同的种子发育阶段以及不同种子大小的大麦品种中表现出差异表达。这两个大麦 I 型 MADS-box 基因受 ABA 和 JA 的诱导。在不同的种子发育阶段以及外源 ABA 处理后，DNA 甲基化差异表明基因表达受到表观遗传调控。对大麦 I 型类似 MADS-box 基因的研究扩展了我们对单子叶作物如大麦胚乳和种子发育过程中基因调控的研究。
