Gil-Humanes Javier, Pistón Fernando, Martín Antonio, Barro Francisco
Departamento de Mejora Genética Vegetal, Instituto de Agricultura Sostenible, CSIC, Córdoba, Spain.
BMC Plant Biol. 2009 May 29;9:66. doi: 10.1186/1471-2229-9-66.
The APETALA2-like genes form a large multi-gene family of transcription factors which play an important role during the plant life cycle, being key regulators of many developmental processes. Many studies in Arabidopsis have revealed that the APETALA2 (AP2) gene is implicated in the establishment of floral meristem and floral organ identity as well as temporal and spatial regulation of flower homeotic gene expression.
In this work, we have cloned and characterised the AP2-like gene from accessions of Hordeum chilense and Hordeum vulgare, wild and domesticated barley, respectively, and compared with other AP2 homoeologous genes, including the Q gene in wheat. The Hordeum AP2-like genes contain two plant-specific DNA binding motifs called AP2 domains, as does the Q gene of wheat. We confirm that the H. chilense AP2-like gene is located on chromosome 5Hch. Patterns of expression of the AP2-like genes were examined in floral organs and other tissues in barley, wheat and in tritordeum amphiploids (barley x wheat hybrids). In tritordeum amphiploids, the level of transcription of the barley AP2-like gene was lower than in its barley parental and the chromosome substitutions 1D/1Hch and 2D/2Hch were seen to modify AP2 gene expression levels.
The results are of interest in order to understand the role of the AP2-like gene in the spike morphology of barley and wheat, and to understand the regulation of this gene in the amphiploids obtained from barley-wheat crossing. This information may have application in cereal breeding programs to up- or down-regulate the expression of AP2-like genes in order to modify spike characteristics and to obtain free-threshing plants.
APETALA2 类基因构成了一个庞大的转录因子多基因家族，在植物生命周期中发挥着重要作用，是许多发育过程的关键调节因子。拟南芥中的许多研究表明，APETALA2（AP2）基因参与花分生组织和花器官特征的建立，以及花同源异型基因表达的时空调控。
在这项工作中，我们分别从野生和驯化的大麦——智利大麦和普通大麦中克隆并鉴定了 AP2 类基因，并与其他 AP2 同源基因进行了比较，包括小麦中的 Q 基因。大麦的 AP2 类基因含有两个植物特有的 DNA 结合基序，称为 AP2 结构域，小麦的 Q 基因也是如此。我们证实，智利大麦的 AP2 类基因位于 5Hch 染色体上。在大麦、小麦和三倍体杂种（大麦×小麦杂种）的花器官和其他组织中检测了 AP2 类基因的表达模式。在三倍体杂种中，大麦 AP2 类基因的转录水平低于其大麦亲本，并且观察到 1D/1Hch 和 2D/2Hch 染色体替换改变了 AP2 基因的表达水平。
这些结果对于理解 AP2 类基因在大麦和小麦穗形态中的作用，以及了解该基因在大麦 - 小麦杂交获得的双二倍体中的调控具有重要意义。这些信息可能应用于谷物育种计划，以上调或下调 AP2 类基因的表达，从而改变穗特征并获得易脱粒的植株。
