Yu Yan, Jiang Yuanyuan, Wang Long, Wu Yichao, Liao Jinqiu, Zhong Mingzhi, Yang Ruiwu, Chen Xingfu, Li Qingmiao, Zhang Li
College of Sciences, Sichuan Agricultural University, Ya'an, Sichuan, China.
College of Life Science, China West Normal University, Nanchong, Sichuan, China.
PeerJ. 2021 Apr 27;9:e11326. doi: 10.7717/peerj.11326. eCollection 2021.
Large-scale heterosis breeding depends upon stable, inherited male sterility lines. We accidentally discovered a male sterility line (SW-S) in the Fprogeny of a Bunge from Shandong, China (purple flowers) crossed with a f. alba from Sichuan, China (white flowers). We sought to provide insights into the pollen development for male sterility in .
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.
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: , and ) 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: , and ). 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 , and the results can be further exploited in functional and mechanism studies.
大规模杂种优势育种依赖于稳定的、可遗传的雄性不育系。我们在中国山东的一个白花翠雀（白花）与中国四川的一个白花翠雀（白花）杂交的F后代中意外发现了一个雄性不育系（SW-S）。我们试图深入了解白花翠雀雄性不育的花粉发育情况。
利用扫描电子显微镜和石蜡切片观察SW-S和可育对照SW-F的表型和细胞学特征，以确定雄性不育的关键阶段。使用Illumina RNA-Seq记录SW-S和SW-F四分体阶段花药的转录组图谱。
石蜡切片显示，不育主要发生在小孢子发育的四分体阶段，在此期间，花药隔室中的绒毡层细胞完全脱落并在不育系中逐渐降解。小孢子细胞周围几乎没有或没有胼胝质沉积。四分体小孢子皱缩且形态异常。因此，选择SW-S和可育对照SW-F四分体阶段的花药进行比较转录组分析。从SW-S和SW-F中总共获得了266,722,270条clean reads，其中包含36,534个基因。SW-S和SW-F中有2,571个差异表达基因（DEG），其中63.5%下调。基因本体（GO）富集分析表明，差异表达基因富集在56个功能组（GO术语）中；其中，所有参与小配子发生和发育成熟的DEG在SW-S中均下调。这些结果通过定量RT-PCR得到证实。这两个GO术语包含18个DEG，其中8个DEG（即： ，和 ）与配子发育相关。有10个DEG与发育和成熟相关，其中3个基因与花粉发育直接相关（即： ，和 ）。因此，我们认为这些基因直接或间接参与了SW-S的花粉败育。我们的研究深入了解了白花翠雀中与不育性状相关的关键基因，其结果可在功能和机制研究中进一步利用。
