Ferradás Yolanda, López Marián, Rey Manuel, González Ma Victoria
Departamento de Fisiología Vegetal, Facultad de Farmacia, Universidad de Santiago, Campus Sur, 15872 Santiago de Compostela, Spain.
Departamento de Biología Vegetal y Ciencia del Suelo, Facultad de Biología, Universidad de Vigo, 36310 Vigo, Spain.
Ann Bot. 2014 Jul;114(1):35-45. doi: 10.1093/aob/mcu073. Epub 2014 Apr 29.
Kiwifruit is a crop with a highly successful reproductive performance, which is impaired by the short effective pollination period of female flowers. This study investigates whether the degenerative processes observed in both pollinated and non-pollinated flowers after anthesis may be considered to be programmed cell death (PCD).
Features of PCD in kiwifruit, Actinidia chinensis var. deliciosa, were studied in both non-pollinated and pollinated stigmatic arms using transmission electron microscopy, DAPI (4',6-diamidino-2-phenylindole) staining, TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling) assays, DNA gel electrophoresis and caspase-like activity assays.
In the secretory tissues of the stigmatic arms, cell organelles disintegrated sequentially while progressive vacuolization was detected. At the same time, chromatin condensation, nuclear deformation, and DNA fragmentation and degradation were observed. These features were detected in both non-pollinated and pollinated stigmatic arms; they were evident in the stigmas of pollinated flowers by the second day after anthesis but only by 4 d after anthesis in non-pollinated flowers. In addition, in pollinated stigmatic arms, these features were first initiated in the stigma and gradually progressed through the style, consistent with pollen tube growth. This timing of events was also observed in both non-pollinated and pollinated stigmatic arms for caspase-3-like activity.
The data provide evidence to support the hypothesis that PCD processes occurring in the secretory tissue of non-pollinated kiwifruit stigmatic arms could be the origin for the observed short effective pollination period. The results obtained in the secretory tissue of pollinated kiwifruit stigmatic arms upon pollination support the idea that PCD might be accelerated by pollination, pointing to the involvement of PCD during the progamic phase.
猕猴桃是一种繁殖性能非常成功的作物，但雌花有效的授粉期较短，这对其繁殖造成了不利影响。本研究调查了花期后在授粉和未授粉花朵中观察到的退化过程是否可被视为程序性细胞死亡（PCD）。
利用透射电子显微镜、DAPI（4',6-二脒基-2-苯基吲哚）染色、TUNEL（末端脱氧核苷酸转移酶介导的dUTP缺口末端标记）分析、DNA凝胶电泳和类半胱天冬酶活性分析，对中华猕猴桃美味变种授粉和未授粉的柱头臂中PCD的特征进行了研究。
在柱头臂的分泌组织中，细胞器依次解体，同时检测到渐进性空泡化。与此同时，观察到染色质浓缩、核变形以及DNA片段化和降解。在未授粉和授粉的柱头臂中均检测到这些特征；它们在授粉花朵的柱头中在花期后第二天就很明显，但在未授粉花朵中直到花期后4天才明显。此外，在授粉的柱头臂中，这些特征首先在柱头中开始，并逐渐通过花柱发展，这与花粉管的生长一致。在未授粉和授粉的柱头臂中，类半胱天冬酶-3样活性也观察到了这种事件发生的时间。
数据提供了证据支持以下假设，即未授粉猕猴桃柱头臂分泌组织中发生的PCD过程可能是观察到的有效授粉期短的根源。授粉后在授粉猕猴桃柱头臂分泌组织中获得的结果支持了PCD可能因授粉而加速的观点，表明PCD在配子体前期参与其中。
