花楸属3种植物的基因组大小与叶气孔特征分析

以糍粑沟花楸(Sorbus cibagouensis H.Peng&Z.J.Yin)、大理花楸(S.hypoglauca(Cardot)Hand.-Mazz.)和川滇花楸(S.vilmorinii C.K.Schneid.)为材料,采用流式细胞术对其基因组大小及倍性进行检测分析,同时应用光学显微镜和扫描电子显微镜对其气孔特征进行观察。结果显示,3种花楸属植物的基因组大小和倍性、气孔特征均存在一定差异。糍粑沟花楸、大理花楸和川滇花楸的基因组大小分别为:(1.480±0.039)pg、(1.513±0.041)pg、(2.675±0.065)pg,在此基础上推断糍粑沟花楸和大理花楸为二倍体、川滇花楸为四倍体植物。显微镜观测发现:3种花楸属植物的气孔器均分布于叶的下表皮,气孔不下陷,保卫细胞无“T”型加厚结构,气孔类型为无规则形;糍粑沟花楸和川滇花楸的气孔器外拱盖光滑,而大理花楸气孔器外拱盖具有短棒状蜡质纹饰;3种植物的气孔器大小存在极显著差异。研究结果表明花楸属植物的基因组大小与倍性呈显著正相关,可用于推断植物的倍性;而气孔器大小和密度与倍性的相关性不大,但气孔特性在种间变化显著,可为种的鉴定提供科学的理论依据。

Variation in genome size and stomatal traits among three Sorbus species

In this paper, ploidy in Sorbus cibagouensis H. Peng & Z. J. Yin, S. hypoglauca (Cardot) Hand.-Mazz., and S. vilmorinii C. K. Schneid was assessed by means of relative genome size using flow cytometry. At the same time, stomatal characteristics were observed by light microscopy and scanning electron microscopy. Based on flow cytometry profiles, the genome sizes of S. cibagouensis, S. hypoglauca, and S. vilmorinii were (1.480±0.039) pg, (1.513±0.041) pg, and (2.675±0.065) pg respectively. The cytotypes of S. cibagouensis (2x), S. hypoglauca (2x), and S. vilmorinii (4x) were also revealed. The stomata of the three Sorbus species did not sink and the guard cells had no ‘T’ type thickening structure. Furthermore, the stomata were distributed in the lower epidermis of the leaves and were anomocytic type. The outer stomatal rim ornamentation of S. cibagouensis and S. vilmorinii was smooth, whereas that of S. hypoglauca was short rod waxy. These results showed that there were significant differences in stomatal size among the three Sorbus species. Furthermore, genome size was positively associated with the ploidy of Sorbus, which could therefore be used for ploidy identification. Although the correlation between stomatal traits and ploidy was not significant, the stomatal characteristics changed significantly among species, which could provide a theoretical basis for species identification.