Comparative transcriptome analysis reveals key insights into male sterility in Salvia miltiorrhiza Bunge

Yan Yu; Yuanyuan Jiang; Long Wang; Yichao Wu; Jinqiu Liao; Mingzhi Zhong; Ruiwu Yang; Xingfu Chen; Qingmiao Li; Li Zhang

doi:10.7717/peerj.11326

Comparative transcriptome analysis reveals key insights into male sterility in Salvia miltiorrhiza Bunge

PeerJ. 2021 Apr 27:9:e11326. doi: 10.7717/peerj.11326. eCollection 2021.

Authors

Yan Yu^{1

2}, Yuanyuan Jiang¹, Long Wang¹, Yichao Wu², Jinqiu Liao³, Mingzhi Zhong¹, Ruiwu Yang³, Xingfu Chen⁴, Qingmiao Li⁵, Li Zhang¹

Affiliations

¹ College of Sciences, Sichuan Agricultural University, Ya'an, Sichuan, China.
² College of Life Science, China West Normal University, Nanchong, Sichuan, China.
³ College of Life Science, Sichuan Agricultural University, Ya'an, Sichuan, China.
⁴ College of Agronomy, Sichuan Agricultural University, Wenjiang, Sichuan, China.
⁵ Sichuan Provincial Key Laboratory of Quality and Innovation Research of Chinese Materia Medica, Sichuan Academy of Chinese Medicine Sciences, Chengdu, Sichuan, China.

Abstract

Background: Large-scale heterosis breeding depends upon stable, inherited male sterility lines. We accidentally discovered a male sterility line (SW-S) in the F₁progeny of a Salvia miltiorrhiza Bunge from Shandong, China (purple flowers) crossed with a S. miltiorrhiza f. alba from Sichuan, China (white flowers). We sought to provide insights into the pollen development for male sterility in S. miltiorrhiza.

Methods: The phenotypic and cytological features of the SW-S and fertile control SW-F were observed using scanning electron microscopy and paraffin sections to identify the key stage of male sterility. Transcriptome profiles were recorded for anthers at the tetrad stage of SW-S and SW-F using Illumina RNA-Seq.

Results: The paraffin sections showed that sterility mainly occurred at the tetrad stage of microspore development, during which the tapetum cells in the anther compartment completely fell off and gradually degraded in the sterile line. There was little-to-no callose deposited around the microspore cells. The tetrad microspore was shriveled and had abnormal morphology. Therefore, anthers at the tetrad stage of SW-S and fertile control SW-F were selected for comparative transcriptome analysis. In total, 266,722,270 clean reads were obtained from SW-S and SW-F, which contained 36,534 genes. There were 2,571 differentially expressed genes (DEGs) in SW-S and SW-F, of which 63.5% were downregulated. Gene Ontology (GO) enrichment analysis indicated that the differentially expressed genes were enriched in 56 functional groups (GO terms); of these, all DEGs involved in microgametogenesis and developmental maturation were downregulated in SW-S. These results were confirmed by quantitative RT-PCR. The two GO terms contained 18 DEGs, among which eight DEGs (namely: GPAT3, RHF1A, phosphatidylinositol, PFAS, MYB96, MYB78, Cals5, and LAT52) were related to gamete development. There were 10 DEGs related to development and maturation, among which three genes were directly related to pollen development (namely: ACT3, RPK2, and DRP1C). Therefore, we believe that these genes are directly or indirectly involved in the pollen abortion of SW-S. Our study provides insight into key genes related to sterility traits in S. miltiorrhiza, and the results can be further exploited in functional and mechanism studies.

Keywords: Differentially expressed genes; Male sterility; RNA-Seq; Salvia miltiorrhiza bunge.

Grants and funding

This research was funded by the National modern agricultural industry technology system Sichuan innovation team (SCCXTD-2020-19), the Sichuan Science and Technology Program (21ZDYF0391, 2020YFN0002, 2019YFS0021), the Sichuan Crops and Animals Breeding Special Project (2016NYZ0036) and the Foundation of Science & Technology Department of Sichuan Province, China (2021JDRC0147). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.