Abstract:

Plant artificial chromosomes (PACs) are human-designed chromosomes that can independently replicate and are stably inherited in plant cells, offering significant potential for genetic engineering. A key advantage of PACs lies in their capacity to accommodate large genetic cassettes while functioning independently of the host genome, establishing PACs as a versatile platform for stable and biosafe genetic manipulation. This review systematically outlines current strategies for PAC construction, methodologies, and future application prospects from a synthetic biology perspective. Current strategies for PAC construction are broadly categorized into top-down and bottom-up approaches. The top-down strategy utilizes endogenous chromosomal elements through techniques such as telomere-mediated chromosomal truncation (TMCT) to generate minichromosomes. In contrast, the bottom-up strategy focuses on the de novo assembly of functional elements, such as centromeres, telomeres, and autonomous replication sequences to synthesize novel chromosomes. Significant progress has also been made in developing extra-nuclear PACs based on plastid or mitochondrial genomes, which benefits from prokaryotic-like transcription and translation systems and offer higher transgene containment. However, the efficient delivery of large PAC constructs into plant cells remains a major technical hurdle. This review evaluates various delivery methodologies to address this challenge. By enabling high-capacity, chromosome-scale engineering, PACs significantly expand the scope of synthetic biology, supporting not only large-scale genomic modifications in existing species but also the de novo design of synthetic gene networks and metabolic pathways. Delivering large PAC constructs into plant cells remains a major bottleneck, and the review evaluates various methods. By enabling chromosomal-level engineering, PACs expand the scope of synthetic biology. Beyond supporting large-scale modifications in existing plants, PACs also allow the de novo assembly of novel gene networks and metabolic pathways, paving the way for engineering plant systems with novel, non-native traits and functions. To fully unleash this potential, several technical challenges must be addressed, including efficient synthesis and delivery of large DNA fragments, enhancement of genetic stability, and the integration of artificial intelligence (AI) with synthetic biology for precise design and functional optimization of PACs. Through iterative design-build-test-learn (DBTL) cycles, PACs can be developed into predictable and stable biological systems. The convergence of these approaches is expected to drive transformative applications across agriculture, pharmaceuticals, and ecology.

Key words: artificial chromosome, genome engineering, plant artificial chromosome, plastid artificial chromosome, synthetic biology

摘要：

植物人工染色体（PAC）是一种人工构建、能在植物细胞中独立复制并稳定遗传的染色体载体，具有高度工程化潜力。其核心优势在于能够承载超大容量基因模块并且独立于天然染色体系统，被视为一种潜在的通用基因操作平台，具有遗传稳定性与安全性。本文从合成生物学视角，系统评述了PAC的构建策略、递送技术，并讨论了其在植物核外基因组中的研究进展。当前，PAC构建主要采取自上而下与自下而上两种策略。然而，PAC的大容量也使其递送更为困难。PAC的构建不仅能在染色体尺度上改造现有植物，更能通过构建全新的基因网络和代谢途径，尝试设计和创造自然界尚未存在的、具有特殊功能或属性的新生命形式，极大地拓展了合成生物学在植物领域的疆界。为充分释放这一潜力，未来研究需攻克超大DNA片段合成与递送的技术瓶颈，持续优化其遗传稳定性，并深度融合人工智能与合成生物技术，以实现PAC的精准设计与高效功能调控，从而驱动其在农业、医药及环保等领域的突破性应用。

关键词: 人工染色体, 基因组工程, 植物人工染色体, 叶绿体人工染色体, 合成生物学