College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China.
BMC Genomics. 2017 Oct 27;18(1):827. doi: 10.1186/s12864-017-4213-5.
The plant-specific gibberellic acid stimulated Arabidopsis (GASA) gene family is critical for plant development. However, little is known about these genes, particularly in fruit tree species.
We identified 15 putative Arabidopsis thaliana GASA (AtGASA) and 26 apple GASA (MdGASA) genes. The identified genes were then characterized (e.g., chromosomal location, structure, and evolutionary relationships). All of the identified A. thaliana and apple GASA proteins included a conserved GASA domain and exhibited similar characteristics. Specifically, the MdGASA expression levels in various tissues and organs were analyzed based on an online gene expression profile and by qRT-PCR. These genes were more highly expressed in the leaves, buds, and fruits compared with the seeds, roots, and seedlings. MdGASA genes were also responsive to gibberellic acid (GA) and abscisic acid treatments. Additionally, transcriptome sequencing results revealed seven potential flowering-related MdGASA genes. We analyzed the expression levels of these genes in response to flowering-related treatments (GA, 6-benzylaminopurine, and sugar) and in apple varieties that differed in terms of flowering ('Nagafu No. 2' and 'Yanfu No. 6') during the flower induction period. These candidate MdGASA genes exhibited diverse expression patterns. The expression levels of six MdGASA genes were inhibited by GA, while the expression of one gene was up-regulated. Additionally, there were expression-level differences induced by the 6-benzylaminopurine and sugar treatments during the flower induction stage, as well as in the different flowering varieties.
This study represents the first comprehensive investigation of the A. thaliana and apple GASA gene families. Our data may provide useful clues for future studies and may support the hypotheses regarding the role of GASA proteins during the flower induction stage in fruit tree species.
植物特有的赤霉素刺激拟南芥（GASA）基因家族对植物发育至关重要。然而，关于这些基因，特别是在果树上的研究知之甚少。
我们鉴定了 15 个拟南芥 GASA（AtGASA）和 26 个苹果 GASA（MdGASA）基因。然后对这些基因进行了特征描述（例如，染色体位置、结构和进化关系）。鉴定的所有拟南芥和苹果 GASA 蛋白都包含一个保守的 GASA 结构域，表现出相似的特征。具体而言，根据在线基因表达谱和 qRT-PCR 分析了各种组织和器官中 MdGASA 的表达水平。与种子、根和幼苗相比，这些基因在叶片、芽和果实中表达水平更高。MdGASA 基因对赤霉素（GA）和脱落酸（ABA）处理也有响应。此外，转录组测序结果揭示了七个潜在与开花相关的 MdGASA 基因。我们分析了这些基因在开花相关处理（GA、6-苄基氨基嘌呤和糖）以及在开花期不同的苹果品种（'Nagafu No.2'和'Yanfu No.6'）中的表达水平。这些候选 MdGASA 基因表现出不同的表达模式。六个 MdGASA 基因的表达水平被 GA 抑制，而一个基因的表达水平上调。此外，在花诱导阶段，6-苄基氨基嘌呤和糖处理以及不同开花品种之间也存在表达水平差异。
本研究代表了对拟南芥和苹果 GASA 基因家族的首次全面研究。我们的数据可能为未来的研究提供有用的线索，并支持关于 GASA 蛋白在果树物种花诱导阶段的作用的假说。
