尖萼报春苣苔叶斑的观察与分析

Identification and Analysis of the Type of Leaf Variegation of Primulina pungentisepala

为探讨尖萼报春苣苔的叶斑类型,对其叶片表皮形态特征、叶片近轴表皮光学特性和叶片解剖组织结构进行分析,测定其斑区与非斑区的叶绿素含量及叶绿素荧光参数(F_(v)/F_(m)),结果显示:尖萼报春苣苔叶斑稳定存在,呈现鱼骨状特征;叶片斑区存在点状反射(spotted pattern)和多角形反射(polygonal pattern)两种反光模式;斑区组织间界限模糊,栅栏组织细胞间及其与近轴表皮细胞间均存在大量空隙;非斑区栅栏组织间无空隙;斑区叶绿体垛叠程度较低且疏松,亲锇颗粒数量较多且密,非斑区叶绿体垛叠程度较高,亲锇颗粒数量较少;斑区叶绿素a含量与非斑区无显著差异,叶绿素b及总叶绿素含量均显著低于非斑区;斑区与非斑区叶绿素荧光参数(F_(v)/F_(m))无显著差异。认为尖萼报春苣苔鱼骨状银白色叶斑主要由栅栏组织细胞与近轴表皮细胞间及栅栏组织细胞间存在的大量细胞空隙形成,同时受到叶绿素含量减少的影响,故其属于兼具空隙型叶斑与叶绿素型叶斑二者特征的新类型。

Several features of Primulina pungentisepala leaf to determine the type of leaf variegation were analyzed.These features include:the morphological characteristics of leaf epidermis,the optical characteristics of leaf adaxial epidermis,the anatomical structure of leaf,and chlorophyll content and chlorophyll fluorescence parameters(F_(v)/F_(m))of leaf.The results indicated relatively stable leaf variegation,showing fishbone-like characteristics.The variegated areas presented two reflection modes:spot reflection(spotted pattern)and polygon reflection(polygonal pattern).Boundaries between tissues were blurry in variegated areas.Conspicuous intercellular spaces existed between the epidermal and palisade cells,and among palisade cells.In non-variegated areas,intercellular spaces were not observed between palisade cells.In variegated areas,the stacking degree was low and chloroplasts were sparse,but profuse and dense osmiophilic were presented.On the contrary,the stacking degree of chloroplast was high with fewer osmiophilic droplets in non-variegated areas.Between the variegated and non-variegated areas,the chlorophyll a content did not differ significantly,while the chlorophyll b content and the total chlorophyll content differed remarkably.The chlorophyll fluorescence parameters(F_(v)/F_(m))showed no significant differences between the variegated and non-variegated areas.Collectively,these results indicate that the formation of silver-white leaf variegation of P.pungentisepala is mainly related to the conspicuous intercellular spaces between the epidermal and palisade cells,and among palisade cells,but is also affected by the reduction of chlorophyll contents.