Key message Stamen degeneration and meiosis failure during the second flowering of ‘Changchun’ were mainly attributed to the coordinated regulation of hormone metabolism, environmental temperature, and genetic factors. Abstract Magnolia × soulangeana ‘Changchun’, a woody ornamental plant, blossoms twice a year after once flower bud differentiation, with fertile flower buds in spring and sterile flower buds in summer. The phenotype of stamens of ‘Changchun’ in summer displays a decrease in length and width, and no pollen, thus aborting. Cytological evidence exhibited that the microspore mother cells in anthers failed to complete meiosis during summer flowering. Compared with spring flowering period, the contents of endogenous substances and hormones decreased in summer, such as IAA/GA, ABA/GA, IAA/ABA hormone ratios also changed, indicating that energy and substances needed for stamen development in summer were insufficient, and hormone balance was broken. Transcriptome data showed that there were 46,230 differentially expressed genes (DEGs) between spring and summer flower buds, including 19,816 up-regulated genes and 26,414 down-regulated genes. Further analysis identified that most of the significantly enriched DEGs were involved in DNA, nucleus, microtubules and other GO items related to meiosis process, which was mutually confirmed with cytological results, suggesting that abnormal meiosis may be the core problem of fertility decline of stamen in summer flower buds of ‘Changchun’. Besides, genes related to hormone signaling and heat stress that may affect stamen development were also differentially expressed. This study provided a basis for further understanding the stamen abortion mechanism of ‘Changchun’, and also provided a reference for exploring the fertility regulation of woody ornamental plants.
Nie, Tangjie & Jiang, Zheng & Sun, Liyong & Chen, Yao & Li, Jia & Yang, Aixiang & Yin, Zengfang. (2022). Analysis on the biological basis of stamen abortion during the second flowering of Magnolia × soulangeana ‘Changchun’. Trees. 10.1007/s00468-022-02306-z.
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