Supporting data for "Genomes of trombidid mites reveal novel predicted allergens and laterally transferred genes associated with secondary metabolism"

Trombidid mites have a unique lifecycle in which only the larval stage is ectoparasitic. In the superfamily Trombiculoidea ('chiggers'), the larvae feed preferentially on vertebrates, including humans. Species in the genus <i>Leptotrombidium</i> are vectors of a potentially fatal bacterial infection, scrub typhus, which affects 1 million people annually. Moreover, chiggers can cause pruritic dermatitis (trombiculiasis) in humans and domesticated animals. In the Trombidioidea (velvet mites), the larvae feed on other arthropods and are potential biological control agents for agricultural pests. Here, we present the first trombidid mites genomes, obtained both for a chigger, <i>Leptotrombidium deliense</i>, and for a velvet mite, <i>Dinothrombium tinctorium</i>.<br>Sequencing was performed using Illumina technology. A 180 Mb draft assembly for <i>D. tinctorium</i> was generated from two paired-end and one mate-pair library using a single adult specimen. For<i>L. deliense</i>, a lower-coverage draft assembly (117 Mb) was obtained using pooled, engorged larvae with a single paired-end library. Remarkably, both genomes exhibited evidence of ancient lateral gene transfer from soil-derived bacteria or fungi. The transferred genes confer functions that are rare in animals, including terpene and carotenoid synthesis. Thirty-seven allergenic protein families were predicted in the <i>L. deliense</i> genome, of which nine were unique. Preliminary proteomic analyses identified several of these putative allergens in larvae.<br>Trombidid mite genomes appear to be more dynamic than those of other acariform mites. A priority for future research is to determine the biological function of terpene synthesis in this taxon and its potential for exploitation in disease control.

绒螨类螨类（Trombidid mites）具有独特的生活史，仅幼虫阶段为外寄生生活。在恙螨总科（Trombiculoidea，俗称“恙螨幼虫（chiggers）”）中，其幼虫偏好寄生于脊椎动物，包括人类。纤恙螨属（Leptotrombidium）内的物种是一种潜在致死性细菌性传染病——丛林斑疹伤寒（scrub typhus）的传播媒介，该疾病每年影响约100万人。此外，恙螨幼虫可引发人类与家养动物的瘙痒性皮炎，即恙螨病（trombiculiasis）。在绒螨总科（Trombidioidea，又称绒螨（velvet mites））中，其幼虫以其他节肢动物为食，可作为农业害虫的潜在生物防治媒介。本研究首次公布了两种绒螨类螨类的全基因组：一种为恙螨幼虫媒介——地里纤恙螨（Leptotrombidium deliense），另一种为绒螨——红绒螨（Dinothrombium tinctorium）。
测序工作采用Illumina测序技术完成。我们利用单只成年红绒螨样本，通过2个双端测序文库与1个配对末端（mate-pair）测序文库，组装得到了长度为180 Mb的红绒螨草图基因组。针对地里纤恙螨，我们通过混合饱血幼虫样本与单个双端测序文库，得到了覆盖度较低的草图基因组（长度117 Mb）。值得注意的是，两种螨类的基因组均存在源自土壤细菌或真菌的古老水平基因转移（lateral gene transfer）事件。这些转移而来的基因赋予了螨类在动物界中较为罕见的功能，包括萜类（terpene）与类胡萝卜素（carotenoid）的合成通路。本研究在地里纤恙螨的基因组中预测得到37个致敏蛋白家族，其中9个为该物种所特有。初步蛋白质组学分析在其幼虫样本中鉴定出了数种上述预测的致敏原。
相较于其他辐螨亚目（acariform mites）螨类，绒螨类螨类的基因组具有更高的动态性。未来研究的重点之一，是明确该类群中萜类合成的生物学功能，以及其在疾病防控领域的应用潜力。