Institute of Dendrology, Polish Academy of Sciences, Kórnik, Poland.
Faculty of Biological Sciences, University of Zielona Góra, Zielona Góra, Poland.
J Plant Res. 2021 Sep;134(5):947-962. doi: 10.1007/s10265-021-01296-2. Epub 2021 Apr 16.
Causes of secondary sexual dimorphism (SSD) in dioecious plants are very poorly understood, especially in woody plants. SSD is shown mainly in mature plants, but little is known about whether secondary sexual dimorphism can occur in juveniles. It is also assumed that stress conditions intensify differences between the sexes due to the uneven reproductive effort. Therefore, the following research hypotheses were tested: (1) secondary sexual dimorphism will be visible in juveniles; (2) unfavourable soil conditions are the cause of more pronounced differences between the sexes. Rooted shoots of the common yew (Taxus baccata L.) and common juniper (Juniperus communis L.), previously harvested from parental individuals of known sex were used in the study. During two growing seasons vegetation periods and four times a year, comprehensive morphological features of whole plants were measured. Some SSD traits were visible in the analysed juveniles. Contrary to expectations, differences were more pronounced in the fertilized treatment. Both species reacted to fertilization in different ways. Female yew had a clearly higher total plant mass, root mass, and mean root area when fertilized, whereas male juniper had a higher root mass when fertilized. Differences between the sexes independent of the fertilization treatment were seen, which can be interpreted as sexual adaptations to a continued reproduction. Female yews and male junipers made better use of fertile habitats. Our study showed that SSD may be innate, and sexual compensatory mechanisms could generate uneven growth and development of both sexes. Because the SSD pattern was rather different in both species, it was confirmed that SSD is connected with the specific life histories of specific species rather than a universal strategy of dioecious species.
雌雄异株植物中次生性别二态性（SSD）的成因知之甚少，尤其是在木本植物中。SSD 主要表现在成熟植物中，但对于次生性别二态性是否会在幼体中发生知之甚少。人们还假设，由于生殖投入的不平衡，胁迫条件会加剧性别差异。因此，提出了以下研究假设：（1）次生性别二态性将在幼体中显现；（2）不利的土壤条件是导致性别差异更加明显的原因。本研究使用了先前从已知性别的亲代个体中采集的普通红豆杉（Taxus baccata L.）和普通刺柏（Juniperus communis L.）的生根枝条。在两个生长季节的植被期和一年中的四个时间点，测量了整个植株的综合形态特征。在分析的幼体中可以看到一些 SSD 特征。与预期相反，在受精处理中差异更为明显。两个物种对施肥的反应方式不同。雌性红豆杉在受精时总植物质量、根质量和平均根面积明显更高，而雄性刺柏在受精时根质量更高。在不受施肥处理影响的情况下，观察到了两性之间的差异，可以将其解释为两性对持续繁殖的适应性。雌性红豆杉和雄性刺柏更好地利用了肥沃的栖息地。我们的研究表明，SSD 可能是先天的，而性补偿机制可能会导致两性生长和发育的不均衡。由于两种物种的 SSD 模式差异很大，证实了 SSD 与特定物种的特定生活史有关，而不是雌雄异株物种的普遍策略。
