Betula L. (birch) is a pioneer hardwood tree species with ecological, economic, and evolutionary importance in the Northern Hemisphere. We sequenced the Betula platyphylla genome and assembled the sequences into 14 chromosomes. The Betula genome lacks evidence of recent whole-genome duplication and has the same paleoploidy level as Vitis vinifera and Prunus mume. Phylogenetic analysis of lignin pathway genes coupled with tissue-specific expression patterns provided clues for understanding the formation of higher ratios of syringyl to guaiacyl lignin observed in Betula species. Our transcriptome analysis of leaf tissues under a time-series cold stress experiment revealed the presence of the MEKK1–MKK2–MPK4 cascade and six additional mitogen-activated protein kinases that can be linked to a gene regulatory network involving many transcription factors and cold tolerance genes. Our genomic and transcriptome analyses provide insight into the structures, features, and evolution of the B. platyphylla genome. The chromosome-level genome and gene resources of B. platyphylla obtained in this study will facilitate the identification of important and essential genes governing important traits of trees and genetic improvement of B. platyphylla.

中文翻译：

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白桦的基因组序列和进化

Betula L.（桦木）是北半球具有生态、经济和进化重要性的先驱硬木树种。我们对白桦基因组并将序列组装成14条染色体。白桦基因组缺乏近期全基因组重复的证据，并且具有与葡萄和梅梅. 木质素途径基因的系统发育分析与组织特异性表达模式相结合，为了解在白桦物种。我们在时间序列冷胁迫实验下对叶组织的转录组分析揭示了 MEKK1-MKK2-MPK4 级联和另外六种丝裂原活化蛋白激酶的存在，这些激酶可以与涉及许多转录因子和耐冷基因的基因调控网络相关联. 我们的基因组和转录组分析提供了对结构、特征和进化的洞察力B. platyphylla基因组。染色体水平的基因组和基因资源B. platyphylla在这项研究中获得的将有助于识别控制树木重要性状和遗传改良的重要和必需基因。B. platyphylla.