Significant improvement of apple (Malus domestica Borkh.) transgenic plant production by pre-transformation with a Baby boom transcription factor

第一作者：Jiajing Chen

第一单位：新西兰植物与食品研究所有限公司

第一通讯：Jia-Long Yao

 Abstarct 

背景回顾：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. 

BBM是AP2/ERF家族的一个成员，已有的研究表明该基因的表达能够提高草本植物的转化与再生。

提出问题：However, this improvement has not been shown clearly for tree species. 

但是，关于该基因在树木树种遗传转化中的作用还不清楚。

主要研究：This study demonstrated that the efficiency of transgenic apple (Malus domestica Borkh.) plant production was dramatically increased by ectopic expression of the MdBBM1 gene. 

本文中，作者发现异位表达MdBBM1基因能够显著增强转基因苹果的再生效率。

结果1-BBM提高再生效率：“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. 

作者首先用带有卡那霉素筛选标记的CaMV35S-MdBBM1载体转化了“皇家嘎拉”苹果。这些MBM转化植株的叶片在组织培养培养基上的芽再生效率显著增强，并且在温室条件下大多数的植株都与CaMV35S-GUS转基因植株相似，表现出近正常的表型，但是仍有轻微的表型变异，即轻微的叶片卷曲。

结果2-BBM转化植株异常表型：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. 

对薄叶片的切片结果显示MBM植株比GUS植株要有更多的细胞，说明异位表达MdBBM1基因能够增强细胞分裂。转录组分析显示，相比于GUS植株，在MBM植株中与生长素、细胞分裂素以及油菜素内酯等植物激素信号通路相关的细胞分裂激活子和抑制子分别得到了增强和减弱。

结果3-预转BBM增加苹果转化再生效率：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. 

通过使用抗除草剂基因载体对八个独立的MBM植株进行再次遗传转化，同时与GUS植株进行比较。GUS植株每100叶外植体产生的转基因植株数量为0-3%，而MBM株系中5个转基因效率为3-8%，3个转基因效率为20-30%。

结论：Our results provided a solution for overcoming the barriers to transgenic plant production in apple, and possibly in other trees.

本文的研究结果为克服苹果转基因植株再生障碍提供了一个解决方案，也可能为其它树木的转基因植株再生提供了参考。

doi: https://doi.org/10.1093/hr/uhab014

Journal: Horticulture Research

First Published: January 28, 2022