壳斗科雌花不同发育时期比较胚胎学特征初探

Primary investigation on comparatively embryology characteristics of different development periods of Fagaceae female flower

关键词:  壳斗科, 解剖学, 形态学, 花粉休眠, 性状演化

Key words:  Fagaceae, anatomy, morphology, pollen dormancy, trait evolution

摘要:

壳斗科是北半球暖温带森林的优势树种之一,具有重要的生态功能和经济开发价值。该研究根据文献资料和野外考察及标本观察,对壳斗科雌花不同发育时期的重要性状进行整理和对比分析,并在系统发育框架下对雌花重要性状的演化趋势进行分析,探讨了上述性状在系统发育树上的演化趋势。选取壳斗科6个属13种雌花发育的5个性状,利用Mesquite在依据Oh & Manos基于核基因CRC和ITS构建的系统发育树上,将性状进行编码和赋值,其中合子形成滞后时间按照数量性状进行分析,其余性状按照质量性状进行分析,并用最大简约法重建雌花形态及受精特征的祖先性状。结果表明:壳斗科雌花的4个重要性状子房室无毛被、胚珠具明显珠柄、子房与花柱比值大和花粉在子房室内休眠是祖征; 合子形成滞后时间的性状是平行演化特征。针对壳斗科胚囊成熟时珠心组织残余结构的解剖术语混乱的现象,建议以后统一采用“珠心柱”指示该结构。该研究结果揭示了壳斗科花及胚胎学性状的演化趋势,也为探讨这些性状演化提供基础资料。

Abstract:

Fagaceae is one of the dominant tree species in warm temperate forest in the Northern Hemisphere, which has important ecological function and economic development value. Previous studies have shown that there is a significant difference in the process of embryo and fertilization between the genus of Fagaceae. At present, under the framework of the system, there is still a lack of knowledge and understanding of the evolution process of these important reproductive traits. In order to clarify the chaotic anatomical term and analyze the evolution trend of the importance traits of female flower under the framework of phylogenetic, on the basis of the relevant domestic and international literature, open-air investigation and specimen identification. In this paper, the important traits of the female flower at different developmental stages were sorted out and analyzed, and the evolution trend of the above traits in the phylogenetic tree was discussed. In this study, five characters from thirteen species belonging to six genera of Fagaceae were chosen, and Mesquite was used to encode and assign the trait according to the phylogenetic tree of the Oh & Manos based on the nuclear gene CRC and ITS. Among these five characters, the trait of delay time of fertilization was analyzed based on quantitative character. At the same time, the remaining traits were analyzed by qualitative character, and the ancestor traits of female flower morphology and fertilization were reconstructed by maximum parsimony. The results showed that there were four important traits in the female flower of the family, such as locule without trichomes, ovule with evident funicle, ratio of locule and style was large and pollen dormancy in locule. These four traits were plesiomorphy, and another trait of delay time of fertilization was parallel evolution characters. According to the use of anatomy terms situation in the past, aiming at the existing problems of anatomy term confusion, suggestions are put forwarded that using the “postament” to represent the remaining tissue structure of nucellar tissue in embryo sac structure at mature stage in the future. This study reveals the trend of the evolution of female flower and embryological traits in Fagaceae, and also provides the information for exploring the evolution of these traits.