五个猕猴桃种的皮孔、气孔器和叶片下表皮微观特征

为了探讨不同种类猕猴桃皮孔、气孔器和叶片下表皮特征的差异及其分类学意义,该文利用光学显微镜观察五个猕猴桃种共计9份样品材料的一年生枝条韧皮部上皮孔的形态,结果发现供试猕猴桃皮孔呈长椭圆形或长梭形,不同种皮孔的长×宽、皮孔密度、皮孔面积和皮孔面积的百分比值存在差异但与种类划分无明显规律,皮孔的宽可明显区分所选4个中华猕猴桃品种。利用扫描电镜观察气孔器和叶片下表皮特征,结果发现猕猴桃气孔器呈宽椭圆形或椭圆形,仅分布在叶背的叶肉区域,气孔器类型有辐射型、环列型、不规则型和不等型4种。中华猕猴桃的气孔器是辐射型,美味猕猴桃的气孔器是环列型,阔叶猕猴桃和毛花猕猴桃的气孔器是不规则型,长果猕猴桃的气孔器是不等型。保卫细胞围绕气孔器排列,与表皮水平或突起。叶片下表皮细胞一般为不规则形或乳状突起,垂周壁浅波状或深波状;表面覆着颗粒状纹饰和分叉单细胞非腺毛,其中阔叶猕猴桃为不分叉单细胞非腺毛,长果猕猴桃多为双分叉单细胞非腺毛,其余为多分叉单细胞非腺毛。部分具有鳞片状蜡质层。气孔器外拱盖内缘浅波状,纹饰光滑或有颗粒状物。测量猕猴桃气孔器长×宽、气孔长轴、气孔器密度,结果发现不同种之间存在差异但与猕猴桃种类划分无明显规律,其气孔器类型与种类划分一致,4个中华猕猴桃品种可通过气孔器的长、气孔长轴和密度大小来区分。此外,新种长果猕猴桃的微表观形态与其他种类存在明显差异,为其识别提供基本的微观依据。

Microscopic characteristics of lenticel, stomatal apparatus and lower epidermis of leaf from five kiwifruit species

In order to explore the difference and taxonomic significance through the characteristics of the lenticel, stomatal apparatus and lower epidermis of leaf of different kiwifruit species, the optical microscope was used to observe kiwifruit lenticels on one-year-old phloem of nine samples from five different species. Kiwifruit lenticels showed long elliptical or spindle shape. The values of length × width, lenticle density, lenticle area and percentage of lenticle area of different species were different and no obvious rule with species division. However, the four Actinidia chinensis varieties from selected samples could be clearly distinguished by the width of the lenticels. The results of scanning electron microscope showed that the stomatal apparatus only existed in blade back and mesophyll area with wide oval and elliptical shape, and the stomatal apparatus types were actinotytic, cyclocytic, anisocytic and anomocytic. Among these species, the stomatal apparatus shape of A. chinensis was actinotytic, the stomatal apparatus shape of A. deliciosa was cyclocytic, the stomatal apparatuses shapes of A. latifolia and A. eriantha were anisocytic, and the stomatal apparatus shape of A. longicarpa was anomocytic. Guard cells were arranged around stomatal apparatus, horizontal or protruding from the lower epidermis. The lower epidermal cells were papillose or anomocytic with sinuate or sinuolate anticlinal wall. The lower epidermis was granulated with furcal pubescence and bifurcate single cell without glandular trichome. Some germplasm had papillose or flake-like waxy layer. Inner margin of outer stomatal rim were sinuolate with ornamentation. According to the measure of length × width, axis and density of stomatal apparatus, there was no obvious rule with kiwifruit species division. However, the stomatal apparatus type and the species division were consistent well. Four A. chinensis varieties could be distinguished by the length, axis of stomatal and density of stomatal apparatus. In addition, there were significant differences in the microapparent morphology between A. longicarpa and other species, which provides microcosmic basis for its identification.