Fischerová Lucie, Gemperlová Lenka, Cvikrová Milena, Matušíková Ildiko, Moravčíková Jana, Gerši Zuzana, Malbeck Jiří, Kuderna Jan, Pavlíčková Jana, Motyka Václav, Eliášová Kateřina, Vondráková Zuzana
Laboratory of Biologically Active Compounds, Institute of Experimental Botany of the Czech Academy of Sciences, Prague, Czechia.
Department of Ecochemistry and Radioecology, University of Ss. Cyril and Methodius in Trnava, Trnava, Slovakia.
Front Plant Sci. 2022 Jul 29;13:968982. doi: 10.3389/fpls.2022.968982. eCollection 2022.
In Norway spruce, as in many other conifers, the germination capacity of somatic embryos is strongly influenced by the desiccation phase inserted after maturation. The intensity of drying during desiccation eminently affected the formation of emblings (i.e., seedlings developed from somatic embryos). Compared to non-desiccated embryos, the germination capacity of embryos desiccated at 100% relative humidity was about three times higher, but the reduction of relative humidity to 95 and 90% had a negative effect on the subsequent embryo development. The water loss observed in these embryos did not lead to an increase in lipid peroxidation, as shown by malondialdehyde levels. Another metabolic pathway in plants that mediates a response to abiotic stresses is directed toward the biosynthesis of polyamines (PAs). The activities of PA biosynthetic enzymes increased steadily in embryos during desiccation at 100% relative humidity, whereas they decreased at lower humidity. The total content of free PAs in the embryos gradually decreased throughout desiccation. The increase in free putrescine (Put) and perchloric acid-insoluble Put conjugates was observed in embryos desiccated at lower humidity. These changes were accompanied to some extent by the transcription of the genes for the PA biosynthesis enzymes. Desiccation at 100% relative humidity increased the activity of the cell wall-modifying enzymes β-1,3-glucanases and chitinases; the activities of these enzymes were also significantly suppressed at reduced humidity. The same pattern was observed in the transcription of some β-1,3-glucanase and chitinase genes. Desiccation treatments triggered metabolic processes that responded to water availability, suggesting an active response of the embryo to the reduction in humidity. A positive effect was demonstrated only for desiccation at high relative humidity. Some of the physiological characteristics described can be used as markers of inappropriate relative humidity during somatic embryo desiccation.
与许多其他针叶树一样，挪威云杉体细胞胚的萌发能力受到成熟后插入的干燥阶段的强烈影响。干燥过程中的干燥强度对胚苗（即由体细胞胚发育而来的幼苗）的形成有显著影响。与未干燥的胚相比，在100%相对湿度下干燥的胚的萌发能力高出约三倍，但相对湿度降至95%和90%对随后的胚发育有负面影响。如丙二醛水平所示，这些胚中观察到的水分流失并未导致脂质过氧化增加。植物中另一条介导对非生物胁迫反应的代谢途径指向多胺（PAs）的生物合成。在100%相对湿度下干燥期间，胚中PA生物合成酶的活性稳步增加，而在较低湿度下则下降。在整个干燥过程中，胚中游离PAs的总含量逐渐降低。在较低湿度下干燥的胚中观察到游离腐胺（Put）和高氯酸不溶性Put共轭物增加。这些变化在一定程度上伴随着PA生物合成酶基因的转录。100%相对湿度下的干燥增加了细胞壁修饰酶β-1,3-葡聚糖酶和几丁质酶的活性；在湿度降低时，这些酶的活性也受到显著抑制。一些β-1,3-葡聚糖酶和几丁质酶基因的转录也观察到相同模式。干燥处理引发了对水分可利用性作出反应的代谢过程，表明胚对湿度降低有积极反应。仅在高相对湿度下干燥显示出积极效果。所描述的一些生理特征可作为体细胞胚干燥期间相对湿度不适宜的标志物。
