Abrahamsson Malin, Valladares Silvia, Merino Irene, Larsson Emma, von Arnold Sara
Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences, P.O. Box 7080, 750 07 Uppsala, Sweden.
Plant Biotechnology Laboratory, Fundación Promiva, Ctra M501 Km 5,1, 28670 Villaviciosa de Odón, Madrid Spain.
In Vitro Cell Dev Biol Plant. 2017;53(2):86-96. doi: 10.1007/s11627-016-9797-y. Epub 2017 Jan 26.
Somatic embryos can be used for propagating forest trees vegetatively, which is of great importance for capturing the genetic gain in breeding programs. However, many economically important species are difficult or impossible to propagate via somatic embryogenesis. In order to get a better understanding of the difficulties to propagate species via somatic embryogenesis, we are studying the developmental pathway of somatic embryos in different cell lines. In a previous study, we showed that the morphology of early somatic embryos in Scots pine () differs between cell lines giving rise to normal or abnormal cotyledonary embryos. In this study, we have compared the proliferation and degeneration pattern of early and late embryos in a normal and abnormal cell line. In both cell lines, a high frequency of the embryos degenerated. Among the degenerating embryos, two main degeneration patterns could be distinguished. In the normal cell line, the embryos degenerated similar to how the subordinate embryos are degraded in the seed. In the abnormal cell line, the degeneration of the embryos resulted in a continuous loop of embryo degeneration and differentiation of new embryos. We observed a similar degeneration pattern when embryogenic tissue was initiated from megagametophytes containing zygotic embryos at the stage of cleavage polyembryony. Based on our results, we suggest that the degeneration pattern in abnormal cell lines starts during initiation of embryogenic cultures.
体细胞胚可用于无性繁殖林木，这对于在育种计划中获取遗传增益至关重要。然而，许多具有重要经济价值的物种很难或无法通过体细胞胚胎发生进行繁殖。为了更好地理解通过体细胞胚胎发生繁殖物种的困难，我们正在研究不同细胞系中体细胞胚的发育途径。在之前的一项研究中，我们表明，欧洲赤松（Pinus sylvestris）早期体细胞胚的形态在产生正常或异常子叶胚的细胞系之间存在差异。在本研究中，我们比较了正常和异常细胞系中早期和晚期胚的增殖和退化模式。在这两种细胞系中，胚的退化频率都很高。在退化的胚中，可以区分出两种主要的退化模式。在正常细胞系中，胚的退化方式类似于种子中从属胚的降解方式。在异常细胞系中，胚的退化导致胚退化和新胚分化的持续循环。当从处于裂生多胚阶段含有合子胚的雌配子体起始胚性组织时，我们观察到了类似的退化模式。基于我们的结果，我们认为异常细胞系中的退化模式在胚性培养物起始时就开始了。
