Institute of Insect Science, Zhejiang University, Hangzhou 310058, China.
State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo 315211, China.
Genome Biol Evol. 2022 Nov 4;14(11). doi: 10.1093/gbe/evac160.
In insects, sex chromosome differentiation often results in unequal gene dosages between sexes. Dosage compensation mechanisms evolve to balance gene expression, but the degree and mechanism of regulation often vary by insect species. In hemipteran species, the small brown planthopper (SBPH), Laodelphax striatellus, is an injurious crop pest, with a sex chromosome type XX in females and XO in males. This species offers the opportunity to study dosage compensation and sex-biased gene expression. In this study, we generated a chromosome-level genome of SBPH using Oxford Nanopore Technologies and high-throughput chromatin conformation capture (Hi-C) technology. We also sequenced RNA-seq data from 16 tissue samples to annotate the genome and analyze gene dosage compensation. We finally obtained a 510.2 megabases (Mb) genome with 99.12% of the scaffolds anchored on 15 chromosomes (14 autosomes and 1 X chromosome) and annotated 16,160 protein-coding genes based on full-length cDNA sequencing data. Furthermore, we found complete dosage compensation in all L. striatellus somatic tissues, but lack of dosage compensation in gonad tissue testis. We also found that female-biased genes were significantly enriched on the X chromosome in all tissues, whereas male-biased genes in gonad tissues were enriched on autosomes. This study not only provides a high-quality genome assembly but also lays a foundation for a better understanding of the sexual regulatory network in hemipteran insects.
在昆虫中，性染色体分化通常导致雌雄之间的基因剂量不均等。剂量补偿机制进化以平衡基因表达，但调节的程度和机制通常因昆虫物种而异。在半翅目物种中，小褐飞虱（SBPH），Laodelphax striatellus，是一种有害的作物害虫，雌性为 XX 型性染色体，雄性为 XO 型。该物种为研究剂量补偿和性别偏向基因表达提供了机会。在这项研究中，我们使用牛津纳米孔技术和高通量染色质构象捕获（Hi-C）技术生成了 SBPH 的染色体水平基因组。我们还从 16 个组织样本中测序了 RNA-seq 数据，以注释基因组并分析基因剂量补偿。我们最终获得了一个 510.2 兆碱基（Mb）的基因组，其中 99.12%的支架锚定在 15 条染色体（14 条常染色体和 1 条 X 染色体）上，并基于全长 cDNA 测序数据注释了 16160 个蛋白质编码基因。此外，我们发现 L. striatellus 所有体细胞组织都存在完全的剂量补偿，但在性腺组织睾丸中缺乏剂量补偿。我们还发现，所有组织中雌性偏向基因在 X 染色体上显著富集，而性腺组织中的雄性偏向基因在常染色体上富集。这项研究不仅提供了高质量的基因组组装，还为更好地理解半翅目昆虫的性调控网络奠定了基础。
