Abstract

BABY BOOM (BBM) is a member of the APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) family and its expression has been shown to improve herbaceous plant transformation and regeneration. However, this improvement has not been shown clearly for tree species. This study demonstrated that the efficiency of transgenic apple (Malus domestica Borkh.) plant production was dramatically increased by ectopic expression of the MdBBM1 gene. “Royal Gala” apple plants were first transformed with a CaMV35S-MdBBM1 construct (MBM) under kanamycin selection. These MBM transgenic plants exhibited enhanced shoot regeneration from leaf explants on tissue culture media, with most plants displaying a close-to-normal phenotype compared with CaMV35S-GUS transgenic plants when grown under greenhouse conditions, the exception being that some plants had slightly curly leaves. Thin leaf sections revealed the MBM plants produced more cells than the GUS plants, indicating that ectopic-expression of MdBBM1 enhanced cell division. Transcriptome analysis showed that mRNA levels for cell division activators and repressors linked to hormone (auxin, cytokinin and brassinosteroid) signalling pathways were enhanced and reduced, respectively, in the MBM plants compared with the GUS plants. Plants of eight independent MBM lines were compared with the GUS plants by re-transforming them with an herbicide-resistant gene construct. The number of transgenic plants produced per 100 leaf explants was 0–3% for the GUS plants, 3–8% for five MBM lines, and 20–30% for three MBM lines. Our results provided a solution for overcoming the barriers to transgenic plant production in apple, and possibly in other trees.

中文翻译：

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通过使用婴儿潮转录因子进行预转化，显着改善苹果（Malus Domestica Borkh.）转基因植物的生产。

 抽象的

BABY BOOM (BBM) 是 APETALA2/乙烯反应因子 (AP2/ERF) 家族的成员，其表达已被证明可以改善草本植物的转化和再生。然而，对于树种来说，这种改进尚未得到明确的体现。这项研究表明， MdBBM1基因的异位表达显着提高了转基因苹果 (Malus Domestica Borkh.) 植物的生产效率。 “Royal Gala”苹果植物首先在卡那霉素选择下用 CaMV 35S-MdBBM1构建体 ( MBM ) 进行转化。这些MBM转基因植物在组织培养基上表现出增强的叶外植体再生能力，与在温室条件下生长的 CaMV 35S-GUS转基因植物相比，大多数植物表现出接近正常的表型，例外是一些植物具有轻微卷曲树叶。薄叶切片显示， MBM植物比GUS植物产生更多细胞，表明MdBBM1的异位表达增强了细胞分裂。转录组分析表明，与GUS植物相比， MBM植物中与激素（生长素、细胞分裂素和油菜素类固醇）信号通路相关的细胞分裂激活剂和阻抑剂的 mRNA 水平分别增强和降低。通过用除草剂抗性基因构建体重新转化八个独立MBM品系的植物与GUS植物进行比较。 对于GUS植物，每 100 个叶外植体产生的转基因植物数量为 0-3%，对于 5 个MBM品系，为 3-8%，对于 3 个MBM品系，为 20-30%。我们的结果为克服苹果以及其他树木中转基因植物生产的障碍提供了解决方案。