We have discovered a novel bacterium, Ochrobactrum haywardense H1 (Oh H1), which is capable of efficient plant transformation. Ochrobactrum is a new host for Agrobacterium-derived vir and T-DNA-mediated transformation. Oh H1 is a unique, non-phytopathogenic species, categorized as a BSL-1 organism. We engineered Oh H1 with repurposed Agrobacterium virulence machinery and demonstrated Oh H1 can transform numerous dicot species and at least one monocot, sorghum. We generated a cysteine auxotrophic Oh H1-8 strain containing a binary vector system. Oh H1-8 produced transgenic soybean plants with an efficiency 1.6 times that of Agrobacterium strain AGL1 and 2.9 times that of LBA4404Thy-. Oh H1-8 successfully transformed several elite Corteva soybean varieties with T0 transformation frequency up to 35%. In addition to higher transformation efficiencies, Oh H1-8 generated high-quality, transgenic events with single-copy, plasmid backbone-free insertion at frequencies higher than AGL1. The SpcN selectable marker gene is excised using a heat shock-inducible excision system resulting in marker-free transgenic events. Approximately, 24.5% of the regenerated plants contained only a single copy of the transgene and contained no vector backbone. There were no statistically significant differences in yield comparing T3 null-segregant lines to wild-type controls. We have demonstrated that Oh H1-8, combined with spectinomycin selection, is an efficient, rapid, marker-free and yield-neutral transformation system for elite soybean.

中文翻译：

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利用新型细菌 Ochrobactrum haywardense H1 开发一种有效的无标记大豆转化方法

我们发现了一种新型细菌Ochrobactrum haywardense H1 ( Oh H1)，它能够有效地进行植物转化。Ochrobactrum是农杆菌衍生的vir和 T-DNA 介导的转化的新宿主。Oh H1 是一种独特的非植物病原体物种，被归类为 BSL-1 生物。我们用改造后的农杆菌毒力机制设计了Oh H1，并证明Oh H1 可以转化多种双子叶植物和至少一种单子叶植物高粱。我们生成了一个含有二元载体系统的半胱氨酸营养缺陷型Oh H1-8 菌株。哦H1-8 产生的转基因大豆植株的效率是农杆菌菌株 AGL1 的 1.6 倍，是 LBA4404Thy- 的 2.9 倍。Oh H1-8成功转化了几个Corteva优质大豆品种，T0转化频率高达35%。除了更高的转化效率外，Oh H1-8 还产生了高质量的转基因事件，其单拷贝、无质粒骨架插入频率高于 AGL1。Spcn _选择标记基因使用热激诱导切除系统切除，导致无标记转基因事件。大约 24.5% 的再生植物仅含有一个转基因拷贝，并且不含载体骨架。将 T3 无效分离株系与野生型对照相比，产量没有统计学上的显着差异。我们已经证明，Oh H1-8 与大观霉素选择相结合，是一种高效、快速、无标记和产量中性的优质大豆转化系统。