Kawamoto Hiroki, Yamanaka Kaori, Koizumi Ayako, Hirata Aiko, Kawano Shigeyuki
Department of Integrated Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan.
Bioscience and Biotechnology Center, Nagoya University, Chikusa, Nagoya, Japan.
Plant Cell Physiol. 2017 Feb 1;58(2):320-328. doi: 10.1093/pcp/pcw193.
Mechanisms of suppression of pistil primordia in male flowers and of stamen primordia in female flowers differ in diclinous plants. In this study, we investigated how cell death and cell cycle arrest are related to flower organ formation in Silene latifolia. Using in situ hybridization and a TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assay, we detected both cell cycle arrest and cell death in suppressed stamens of female flowers and suppressed pistils of male flowers in S. latifolia. In female flowers infected with Microbotryum lychnidis-dioicae, developmental suppression of stamens is released, and cell cycle arrest and cell death do not occur. Smut spores are formed in S. latifolia anthers infected with M. lychnidis-dioicae, followed by cell death in the endothelium, middle layer, tapetal cells and pollen mother cells. Cell death is difficult to detect using a fluorescein isothiocyanate-labeled TUNEL assay due to strong autofluorescence in the anther. We therefore combined a TUNEL assay in an infrared region with transmission electron microscopy to detect cell death in anthers. We show that following infection by M. lychnidis-dioicae, a TUNEL signal was not detected in the endothelium, middle layer or pollen mother cells, and cell death with outflow of cell contents, including the nucleoplast, was observed in tapetal cells.
在雌雄异花植物中，雄花中雌蕊原基和雌花中雄蕊原基的抑制机制有所不同。在本研究中，我们调查了细胞死亡和细胞周期停滞与宽叶蝇子草花器官形成之间的关系。通过原位杂交和TUNEL（末端脱氧核苷酸转移酶dUTP缺口末端标记）检测，我们在宽叶蝇子草雌花中受抑制的雄蕊和雄花中受抑制的雌蕊中均检测到了细胞周期停滞和细胞死亡。在感染了二型麦角菌的雌花中，雄蕊的发育抑制被解除，细胞周期停滞和细胞死亡均未发生。在感染二型麦角菌的宽叶蝇子草花药中形成了黑粉孢子，随后在内皮层、中层、绒毡层细胞和花粉母细胞中发生细胞死亡。由于花药中强烈的自发荧光，使用异硫氰酸荧光素标记的TUNEL检测很难检测到细胞死亡。因此，我们将红外区域的TUNEL检测与透射电子显微镜相结合，以检测花药中的细胞死亡。我们发现，在感染二型麦角菌后，在内皮层、中层或花粉母细胞中未检测到TUNEL信号，而在绒毡层细胞中观察到了细胞内容物（包括核质体）外流的细胞死亡现象。
