Department of Plant Biology, University of California, Davis, CA, USA.
Department of Plant Sciences, University of California, Davis, CA, USA.
Plant Reprod. 2024 Nov 29;38(1):3. doi: 10.1007/s00497-024-00512-y.
Induction of parthenogenesis (embryo formation from unfertilized egg cells) by embryogenic transcription factors is associated with twin formation at high frequencies, and involves two distinct mechanisms. Synthetic apomixis has been achieved through the induction of parthenogenesis by ectopic expression of the Baby Boom family of transcription factors. An associated phenomenon from this process is the formation of polyembryony including twin progeny at high frequencies, but the underlying mechanisms have not been explored. Here, we provide a brief description of the phenomenon, discuss potential mechanisms for twin formation in flowering plants, propose two possible models for their occurrence, and evaluate the available evidence from both dizygotic and monozygotic twins in relation to these models. The two proposed models are independent, but they can operate in combination. We conclude that both models are required to explain the types of twins and triplets that we and others have observed. These models provide future directions for basic research, as well as suggest possible approaches towards reducing polyembryony when incorporating synthetic apomixis into crop plants such as maize where twinning is not desirable.
通过胚胎发生转录因子诱导孤雌生殖（未受精卵细胞形成胚胎）与高频双胞胎形成有关，涉及两种不同的机制。通过异位表达 Baby Boom 转录因子家族诱导孤雌生殖，已经实现了人工无融合生殖。该过程的一个相关现象是多胚形成，包括高频双胞胎后代，但潜在机制尚未探索。在这里，我们简要描述了这一现象，讨论了开花植物中双胞胎形成的潜在机制，提出了两种可能的发生模型，并根据这些模型评估了来自双生子和单卵双胞胎的现有证据。这两个提出的模型是独立的，但它们可以组合使用。我们得出的结论是，需要这两个模型来解释我们和其他人观察到的双胞胎和三胞胎的类型。这些模型为基础研究提供了未来的方向，并为在将人工无融合生殖纳入玉米等作物时减少多胚形成提供了可能的方法，因为在玉米中，多胚形成是不理想的。
