Ice plant (Mesembryanthemum crystallinum), a member of the Aizoaceae family, is a typical halophyte crop and a model plant for studying the mechanism of transition from C3 photosynthesis to crassulacean acid metabolism (CAM). Here, we report a high-quality chromosome-level ice plant genome sequence. This 98.05% genome sequence is anchored to nine chromosomes, with a total length of 377.97 Mb and an N50 scaffold of 40.45 Mb. Almost half of the genome (48.04%) is composed of repetitive sequences, and 24 234 genes have been annotated. Subsequent to the ancient whole-genome triplication (WGT) that occurred in eudicots, there has been no recent whole-genome duplication (WGD) or WGT in ice plants. However, we detected a novel WGT event that occurred in the same order in Simmondsia chinensis, which was previously overlooked. Our findings revealed that ice plants have undergone chromosome rearrangements and gene removal during evolution. Combined with transcriptome and comparative genomic data and expression verification, we identified several key genes involved in the CAM pathway and constructed a comprehensive network. As the first genome of the Aizoaceae family to be released, this report will provide a rich data resource for comparative and functional genomic studies of Aizoaceae, especially for studies on salt tolerance and C3-to-CAM transitions to improve crop yield and resistance.

中文翻译：

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高质量的冰植物参考基因组分析提供了对基因组进化的见解，并允许探索参与从 C3 到 CAM 途径转变的基因

冰植物（Mesembryanthemum crystallinum）是偶氮科的一员，是典型的盐生植物，是研究C3光合作用向景天酸代谢（CAM）转变机制的模式植物。在这里，我们报告了高质量的染色体级冰植物基因组序列。这个 98.05% 的基因组序列锚定在 9 条染色体上，总长度为 377.97 Mb，N50 支架为 40.45 Mb。几乎一半的基因组（48.04%）由重复序列组成，24 234个基因已被注释。在真双子叶植物中发生古老的全基因组三倍复制 (WGT) 之后，最近在冰植物中没有出现全基因组复制 (WGD) 或 WGT。然而，我们检测到在Simmondsia chinensis中以相同顺序发生的新 WGT 事件，这是以前被忽略的。我们的研究结果表明，冰植物在进化过程中经历了染色体重排和基因去除。结合转录组和比较基因组数据和表达验证，我们确定了参与CAM途径的几个关键基因，并构建了一个全面的网络。作为第一个发布的偶氮科基因组，本报告将为偶氮科的比较和功能基因组研究提供丰富的数据资源，特别是为研究耐盐性和C3-to-CAM转换以提高作物产量和抗性提供了丰富的数据资源。