Data from: Monophyletic origin and evolution of the largest crucifer genomes

Clade E, or the Hesperis-clade is one of the major Brassicaceae (Crucifereae) clades comprising some 48 genera and 351 species classified into seven tribes and is predominantly distributed across arid and montane regions of Asia. Several taxa have socio-economic significance, being important ornamental but also weedy and invasive species. From the comparative genomic perspective, the clade is noteworthy as it harbors species with the largest crucifer genomes but low numbers of chromosomes (n = 5 - 7). By applying comparative cytogenetic analysis and whole-chloroplast phylogenetics, we constructed the first partial and complete cytogenetic maps for selected representatives of Clade E tribes and investigated their relationships in a family-wide context. The Hesperis-clade is a well-supported monophyletic lineage comprising seven tribes: Anchonieae, Buniadeae, Chorisporeae, Dontostemoneae, Euclidieae, Hesperideae, and Shehbazieae. The clade diverged from other Brassicaceae crown-group clades during the Oligocene, followed by subsequent Miocene tribal diversifications in central/south-western Asia. The inferred Ancestral Karyotype of Clade E (CEK, n = 7) originated from an older n = 8 genome, which was also the purported progenitor of tribe Arabideae (KAA genome). In most taxa of Clade E, the seven linkage groups of CEK either remained conserved (Chorisporeae) or were reshuffled by chromosomal translocations (Euclidieae). In c. 50% of Anchonieae and Hesperideae species, the CEK genome has undergone descending dysploidy toward n = 6 (5). This genomic data elucidates early genome evolution in Brassicaceae, and paves the way for future whole-genome sequencing and assembly efforts in this, as yet genomically neglected group of crucifer plants.演化支E（Clade E），又称香花芥演化支（Hesperis-clade），是十字花科（Brassicaceae，原分类名为Crucifereae）的主要演化支之一，包含约48个属、351个物种，划分为7个族，主要分布于亚洲的干旱与山地区域。该演化支内多个类群具有重要社会经济价值：既是优质观赏植物，同时也可成为杂草与入侵物种。从比较基因组学视角来看，该演化支极具研究价值：其包含的物种拥有十字花科中最大的基因组，但染色体数目极少（染色体基数n=5~7）。本研究通过比较细胞遗传学分析与全叶绿体系统发育学分析，为香花芥演化支各选定族的代表类群构建了首批部分及完整的细胞遗传图谱，并在十字花科的整体分类框架下探究了这些类群间的系统发育关系。香花芥演化支是一个得到充分统计支持的单系支系，包含7个族：锚果芥族（Anchonieae）、匙荠族（Buniadeae）、离子芥族（Chorisporeae）、花旗竿族（Dontostemoneae）、高原芥族（Euclidieae）、香花芥族（Hesperideae）以及谢氏芥族（Shehbazieae）。该演化支于渐新世时期与十字花科冠群的其他演化支发生分化，随后在中新世时期于亚洲中南部与西南部发生族级类群的多样化演化。本研究推断的香花芥演化支祖先核型（CEK，n=7）起源于更古老的n=8基因组，而该基因组同时被认为是阿拉伯芥族（Arabideae）的推测祖先核型（KAA基因组）。在香花芥演化支的多数类群中，CEK的7个连锁群要么保持结构保守（如离子芥族），要么通过染色体易位发生重排（如高原芥族）。在约50%的锚果芥族与香花芥族物种中，CEK基因组已发生下行非整倍化，染色体基数向n=6（部分类群为n=5）演化。该基因组数据阐明了十字花科的早期基因组演化历程，同时为这一迄今在基因组学领域尚未得到充分研究的十字花科类群的后续全基因组测序与组装工作铺平了道路。