3-Hydroxypropanoic acid contributing to pollen abortion in ogura cytoplasmic male sterility of Brassica napus

BACKGROUND: The Ogura-type male sterile cytoplasm is commonly used in Brassicaceae plants, but its sterility mechanism still requires further investigation. RESULTS: The flower buds of Ogura CMS line ZJCMS1A and its maintainer line ZJCMS1B based on their length < 2 mm, 2 mm-3 mm, 3 mm-4 mm, grouped A2, A3, A4 and B2, B3, B4, respectively. Anthers were excised from flower buds of each group for transcriptome and metabolome sequencing. Differential comparison analysis, Venn analysis, Multi-omics Integration KEGG enrichment analysis, and pathway network analysis were performed on the data from different groups. The results showed that the abnormal propanoate metabolic pathway in ZJCMS1A was closely related to pollen abortion. The content of 3-hydroxypropionic acid (3-HP) in the propanoate metabolic pathway was higher in ZJCMS1A than in ZJCMS1B in the three comparisons A2 vs B2, A3 vs B3, and A4 vs B4. Furthermore, the content of 3-HP in ZJCMS2A flower buds was also higher than in ZJCMS2B. Quantification of 3-HP content revealed that the content in the stems, leaves, and flower buds of ZJCMS1A was higher than that in the corresponding tissues of ZJCMS1B. The 3-HP content in the flower buds of ZJCMS1A was 8.1% higher than that in ZJCMS1B. Treatment of rapeseed plants with 20 mM and 50 mM 3-HP showed that starch accumulation in pollen grains was affected. CONCLUSIONS: These results indicated that pollen abortion in Ogura-type CMS is closely related to abnormalities in the propanoate metabolic pathway, particularly the abnormal accumulation of 3-HP, which may participate in the pollen abortion process.