The chloroplast genome of the desiccation-tolerant moss Pseudocrossidium replicatum (Taylor) R.H. Zander

Abstract Mosses in conjunction with hornworts and liverworts are collectively referred to as bryophytes. These seedless, nonvascular plants are the closest extant relatives of early terrestrial plants and their study is essential to understand the evolutionary first steps of land plants. Here we report the complete chloroplast (cp) genome sequence of Pseudocrossidium replicatum, a moss belonging to the Pottiaceae family that is common in the central highlands of Mexico, in South America, in southern USA, and in Kenia. The cp genome (plastome) of P. replicatum is 123,512 bp in size, comprising inverted repeats of 9,886 bp and single-copy regions of 85,146 bp (LSC) and 18,594 bp (SSC). The plastome encodes 82 different proteins, 31 different tRNAs, and 4 different rRNAs. Phylogenetic analysis using 16 cp protein-coding genes demonstrated that P. replicatum is closely related to Syntrichia ruralis, and the most basal mosses are Takakia lepidozioides followed by Sphagnum palustre. Our analysis indicates that during the evolution of the mosses’ plastome, eight genes were lost. The complete plastome sequence reported here can be useful in evolutionary and population genetics.

摘要：苔藓与角苔、地钱共同被称为苔藓植物（bryophytes）。这类无籽、无维管的植物是现存最早陆生植物的近亲，对其开展研究对于解析陆地植物的演化起源至关重要。本研究报道了拟反扭藓（Pseudocrossidium replicatum）的完整叶绿体基因组（chloroplast genome，cp基因组）序列。该苔藓隶属于丛藓科（Pottiaceae），在墨西哥中部高原、南美洲、美国南部以及肯尼亚均有广泛分布。该物种的cp基因组（质体基因组，plastome）全长123512 bp，由长度为9886 bp的反向重复序列，以及85146 bp的大单拷贝区（LSC）和18594 bp的小单拷贝区（SSC）组成。该质体基因组共编码82种蛋白质、31种转运RNA（tRNA）以及4种核糖体RNA（rRNA）。基于16个cp基因组蛋白编码基因的系统发育分析表明，拟反扭藓与Syntrichia ruralis亲缘关系密切；最基部的苔藓类群为藻苔（Takakia lepidozioides），其次为泥炭藓（Sphagnum palustre）。本研究分析显示，在苔藓质体基因组的演化过程中，共有8个基因发生了丢失。本研究报道的完整质体基因组序列，可用于进化遗传学与群体遗传学相关研究。