Identification and characterization of MicroRNAs in gonads of Helicoverpa armigera (Lepidoptera: Noctuidae)

Authors: LI, LEYAO - Zhengzhou University; WANG, SHAN - Zhengzhou University; HUANG, KAIYUAN - Zhengzhou University; ZHANG, YUTING - Zhengzhou University; LI, YALU - Zhengzhou University; ZHANG, MIN - Zhengzhou University; HUANG, JINYONG - Zhengzhou University; DENG, ZHONGYUAN - Zhengzhou University; Ni, Xinzhi; LI, XIANCHUN - University Of Arizona

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2021
Publication Date: 8/19/2021
Citation: Li, L., Wang, S., Huang, K., Zhang, Y., Li, Y., Zhang, M., Huang, J., Deng, Z., Ni, X., Li, X. 2021. Identification and characterization of MicroRNAs in gonads of Helicoverpa armigera (Lepidoptera: Noctuidae). Insects. 12:749. https://doi.org/10.3390/insects12080749.
DOI: https://doi.org/10.3390/insects12080749

Interpretive Summary: For most insects, the full development of the testis and ovary directly determines their reproductive ability. The old-world cotton bollworm (a close relative of the corn earworm in the North America) is a polyphagous crop pest due to its broad range of host plants and high reproductive potential, which causes huge economic losses to agricultural crop production worldwide. Acting as a type of post-transcriptional regulatory factor, microRNAs participate in the gonadal development and reproductive regulation of the old-world cotton bollworm. In the current study, we used the old-world cotton bollworm as a model system to identify and characterize the microRNAs and to determine their potential functions in the testis and ovary development. The libraries of the small RNAs of not more than 50 basepairs for the testis and ovary tissues were constructed and sequenced. Length distribution analysis showed that the main types of small RNAs in the testis and ovary were different: more piwi-interacting RNA but less microRNA in the ovary than in the testis. Among the 74 known microRNAs examined, 60 of them existed in the ovary, while 72 existed in the testis tissue. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses indicated that the eight gonad-biased microRNAs had many target transcripts involved in the reproduction tissue development process. The current study has established the critical foundation for comprehensive understanding of the roles of microRNAs in the development of ovary and testis tissues in the prolific and polyphagous crop pests. The findings could be utilized in designing novel pest management tools, such as new RNA interference techniques targeting gonad tissues of insect pests of economic importance.

Technical Abstract: The high fecundity of the most destructive pest Helicoverpa armigera and its great resistance risk to insecticides and Bt crops make the reproductive-destruction-based control of this pest extremely appealing. To find suitable targets for disruption of its reproduction, we observed the testis and ovary development of H. armigera and conducted deep sequencing of the ovary and testis small RNAs of H. armigera and quantitative RT-PCR (RT-qPCR) validation to identify reproduction-related micro RNAs (miRNAs). A total of 7,592,150 and 8,815,237 clean reads were obtained from the testis and ovary tissues, respectively. After further analysis, we obtained 173 novel and 74 known miRNAs from the two libraries. Among the 74 known miRNAs, 60 miRNAs existed in the ovary and 72 existed in the testis. Further RT-qPCR validation of five miRNAs from the ovary and six miRNAs from the testis confirmed eight of them were indeed ovary- (miR-989a, miR-263-5p, miR-34) or testis biased (miR-2763, miR-998, miR-2c, miR-2765, miR-252a-5p). The eight ovary- or testis-biased miRNAs had a total of 30,172 putative non-redundant target transcripts, as predicted by miRanda and RNAhybrid. Many of these target transcripts are assigned to reproduction-related gene oncology (GO) terms (e.g., oocyte maturation, vitellogenesis, spermatogenesis) and are members of multiple reproduction-related GO term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, such as, the Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) pathway (JAK-STAT) signaling pathway, oocyte meiosis, the insulin signaling pathway, and insect hormone biosynthesis. These results suggest that the eight gonad-biased miRNAs play important roles in reproduction and may be used as the targets for the development of reproductive-destruction-based control of H. armigera and, possibly, other lepidopteran pests.