Table1_Comparative analyses of eight complete plastid genomes of two hemiparasitic Cassytha vines in the family Lauraceae.docx

Cassytha is the sole genus of hemiparasitic vines (ca. 20 spp.) belonging to the Cassytheae tribe of the Lauraceae family. It is extensively distributed in tropical and subtropical regions. In this study, we determined the complete plastid genome sequences of C. filiformis and C. larsenii, which do not possess the typical quadripartite structure. The length of C. filiformis plastomes ranged from 114,215 to 114,618 bp, whereas that of C. larsenii plastomes ranged from 114,900 to 114,988 bp. Comparative genomic analysis revealed 1,013 mutation sites, four large intragenomic deletions, and five highly variable regions in the eight plastome sequences. Phylogenetic analyses based on 61 complete plastomes of Laurales species, 19 ITS sequences, and trnK barcodes from 91 individuals of Cassytha spp. confirmed a non-basal group comprising individuals of C. filiformis, C. larsenii, and C. pubescens in the family Lauraceae and proposed a sister relationship between C. filiformis and C. larsenii. Further morphological comparisons indicated that the presence or absence of hairs on the haustoria and the shape or size of fruits were useful traits for differentiating C. filiformis and C. larsenii.

Cassytha 为 Lauraceae 科 Cassytheae 族的独有属，包含约 20 种半寄生藤本植物。其分布广泛，遍及热带及亚热带地区。本研究中，我们确定了 C. filiformis 和 C. larsenii 的完整叶绿体基因组序列，这两个物种不具有典型的四分体结构。C. filiformis 的叶绿体基因组长度介于 114,215 至 114,618 碱基对之间，而 C. larsenii 的叶绿体基因组长度介于 114,900 至 114,988 碱基对之间。通过比较基因组分析，我们发现了 1,013 个突变位点、四个大型基因组内缺失以及五个高度可变区域。基于 61 个 Laurales 物种完整的叶绿体基因组、19 个 ITS 序列以及 91 个 Cassytha 物种个体的 trnK 条形码进行的系统发育分析，证实了 C. filiformis、C. larsenii 和 C. pubescens 在 Lauraceae 科中构成一个非基群，并提出了 C. filiformis 与 C. larsenii 之间的姐妹群关系。进一步的形态学比较表明，吸器的毛发生存与否以及果实形状或大小是区分 C. filiformis 和 C. larsenii 的有用特征。