Zhang Ming, Wang Aibin, Qin Mou, Qin Xuejing, Yang Shiwen, Su Shuchai, Sun Yongjiang, Zhang Lingyun
Key Laboratory of Forest Silviculture and Conservation of the Ministry of Education, The College of Forestry, Beijing Forestry University, Beijing, China.
Baise Forestry Bureau of Guangxi Zhuang Autonomous Region, Baise, China.
Front Plant Sci. 2021 Mar 26;12:644389. doi: 10.3389/fpls.2021.644389. eCollection 2021.
Abel. is an important woody oil species; however, the shortage of rapid and industrialized seedling culture is a large constraint on the development of the tea oil industry. Somatic embryogenesis (SE) is one of the main powerful biotechnological tools for plant mass regeneration, but the largely unknown SE in limits the scale production of clonal plants. In this study, we described a high-efficiency SE system via direct and indirect pathways in and investigated the effect of genotype, explant age and phytohormones on SE. In the direct pathway, somatic embryos were highly induced from immature seeds 220 days after full blossom, and the development of embryoids was achieved with a combination of 0.19 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.05 mg/L thidiazuron (TDZ). In the indirect pathway, embryogenic calli were induced from the same explants in medium containing 1.5 mg/L 2,4-D, while 0.75 mg/L 2,4-D treatment led to high proliferation rates for embryogenic calli. The addition of 0.19 mg/L 2,4-D alone stimulated the production of globular embryos while causing a 75% loss of the induction rate in the heart embryo stage. Upon transfer of the globular embryos to phytohormone-free medium, an optimal induction rate of 62.37% from globular embryos to cotyledonary embryos was obtained. These data suggest that the subsequent differentiation process after the globular embryo stage in ISE is more similar to an endogenous phytohormones-driven process. Mature embryos germinated to produce intact plantlets on half-strength MS basal medium with a regeneration rate of 63.67%. Histological analysis confirmed the vascular bundle isolation of embryoids from the mother tissue. We further studied the different varieties and found that there were no significant genotype differences for SE induction efficiency in . Thus, we established a high-efficiency induction system for direct and indirect somatic embryogenesis (ISE) in and regenerated intact plantlets via SE, not organogenesis. ISE has a more complicated induction and regulatory mechanism than direct somatic embryogenesis. The improved protocol of SE would benefit mass propagation and genetic manipulation in .
油桐是一种重要的木本油料树种；然而，快速且工业化育苗的短缺是制约油茶产业发展的一个重大因素。体细胞胚胎发生（SE）是植物大规模再生的主要强大生物技术工具之一，但油桐中 largely unknown SE 限制了克隆植物的规模化生产。在本研究中，我们描述了一种通过直接和间接途径在油桐中建立的高效 SE 体系，并研究了基因型、外植体年龄和植物激素对 SE 的影响。在直接途径中，在盛花 220 天后从未成熟种子中高效诱导出体细胞胚，通过 0.19 mg/L 2,4 - 二氯苯氧乙酸（2,4 - D）和 0.05 mg/L 噻苯隆（TDZ）的组合实现胚状体的发育。在间接途径中，在含有 1.5 mg/L 2,4 - D 的培养基中从相同外植体诱导出胚性愈伤组织，而 0.75 mg/L 2,4 - D 处理导致胚性愈伤组织的高增殖率。单独添加 0.19 mg/L 2,4 - D 刺激球形胚的产生，同时导致心形胚阶段诱导率损失 75%。将球形胚转移到无植物激素的培养基上，从球形胚到子叶胚的最佳诱导率为 62.37%。这些数据表明，油桐体细胞胚胎发生中球形胚阶段后的后续分化过程更类似于内源植物激素驱动的过程。成熟胚在 1/2 强度的 MS 基本培养基上萌发产生完整植株，再生率为 63.67%。组织学分析证实胚状体与母体组织的维管束分离。我们进一步研究了不同品种，发现油桐中 SE 诱导效率没有显著的基因型差异。因此，我们建立了油桐直接和间接体细胞胚胎发生（ISE）的高效诱导体系，并通过 SE 而非器官发生再生出完整植株。ISE 具有比直接体细胞胚胎发生更复杂的诱导和调控机制。改进的 SE 方案将有利于油桐的大规模繁殖和遗传操作。
