Denaeghel Hanne E R, Van Laere Katrijn, Leus Leen, Lootens Peter, Van Huylenbroeck Johan, Van Labeke Marie-Christine
Applied Genetics and Breeding, Plant Sciences Unit, Flanders Research Institute for Agriculture, Fisheries and Food, Melle, Belgium.
Department of Plant Production, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
Front Plant Sci. 2018 Mar 20;9:354. doi: 10.3389/fpls.2018.00354. eCollection 2018.
To induce new variation within the genus, chromosome doubling was performed in , and , three important species within this genus of mainly evergreen woody ornamental species. Obtained tetraploids and diploid controls were analyzed for rooting capacity, leaf and flower characteristics, and plant architecture using image analysis and cold tolerance. In the present study, a breeders' collection of 23 accessions was characterized cytogenetically and described morphologically. All analyzed species and cultivars were diploid (2n = 2x = 24), with exception of , a tetraploid. Today, breeding in is limited to lucky finds in seedling populations and few efforts in interspecific hybridization. Three selected species underwent an chromosome doubling with both oryzalin and trifluralin applied as either a continuous or shock treatment. The treatments successfully induced polyploids in all three species. Image analysis revealed that tetraploid had decreased shoot length (from 3.8 to 1.3 cm), higher circularity and more dense growth habit compared to diploids. No significant changes in cold tolerance were seen. Tetraploid did not differ in shoot length, but an increased outgrowth of axillary buds on the main axis led to denser plants. For tetraploid , an increase in plant height (from 4.9 to 5.5 cm) was observed together with a large decrease in circularity and density due to a more polar outgrowth of branches on the main axis. tetraploids bore larger flowers than diploids and had an increased cold tolerance (from -7.7 to -11.8°C). Leaf width and area of tetraploids increased for both and , while a decrease was seen in genotypes. For all three species, the rooting capacity of the tetraploids did not differ from the diploids. We conclude that the effect of polyploidization on was highly variable and species dependent.
为了在该属内诱导新的变异，对该属内三种主要常绿木本观赏植物的重要物种进行了染色体加倍操作。使用图像分析和耐寒性对获得的四倍体和二倍体对照进行生根能力、叶和花的特征以及植株形态分析。在本研究中，对23个品种的育种材料进行了细胞遗传学特征分析并进行了形态学描述。所有分析的物种和品种均为二倍体（2n = 2x = 24），但有一种四倍体除外。如今，该属的育种仅限于在幼苗群体中偶然发现以及在种间杂交方面的少量努力。选择的三个该属物种使用氨磺乐灵和氟乐灵进行了染色体加倍，采用连续或休克处理。这些处理成功地在所有三个物种中诱导出了多倍体。图像分析显示，与二倍体相比，四倍体的茎长度减少（从3.8厘米降至1.3厘米），圆度更高，生长习性更密集。耐寒性未见显著变化。四倍体的茎长度没有差异，但主轴上腋芽的生长增加导致植株更密集。对于四倍体，观察到植株高度增加（从4.9厘米增至5.5厘米），同时由于主轴上枝条的极性生长增加，圆度和密度大幅降低。该属四倍体的花比二倍体大，耐寒性增强（从-7.7°C降至-11.8°C）。对于该属的两个物种，四倍体的叶宽和叶面积增加，而在另一个基因型中则减少。对于所有三个物种，四倍体的生根能力与二倍体没有差异。我们得出结论，多倍体化对该属的影响高度可变且因物种而异。
