中国秋海棠属植物的自然杂交发生及其特点  

Occurrence and characteristics of natural hybridization in Begonia in China

作　　者：田代科[1,2] 李春[1,3] 肖艳[1,2] 付乃峰[1,2] 童毅[1,2] 吴瑞娟[1,2] 

机构地区：[1]上海辰山植物园中国科学院上海辰山植物科学研究中心,上海201602 [2]上海市资源植物功能基因组学重点实验室,上海201602 [3]四川省芦山县林业局,四川芦山625600

出　　处：《生物多样性》2017年第6期654-674,共21页Biodiversity Science

基　　金：上海市绿化与市容管理局科技公关项目(F122416);国家自然科学基金(3170199)

摘　　要：自然杂交在植物界中十分普遍,一直是物种形成和进化研究的热点。秋海棠属(Begonia)为世界最大植物属之一,其种类繁多,但关于自然杂交的相关报道很少。系统调查秋海棠属的自然杂交不仅有利于理解该属植物的多样性,也是弄清其资源和解决物种分类问题不可缺少的环节。本文通过对国产秋海棠属植物自然杂交现象的系统调查和分析,发现总计29种(占国产已知200种秋海棠的约15%)参与了杂交,产生了31个自然"杂种"约50个居群。其中,掌叶秋海棠(B.hemsleyana)和粗喙秋海棠(B.longifolia)参与杂交程度最高,分别与另外的8种和7种秋海棠发生了杂交;而裂叶秋海棠(B.palmata)发生杂交的居群最多,达16处。自然杂交以云南(尤其是南部)发生频率最高,一共有20种参与,产生了31处杂交居群;台湾和广西次之。杂交多为单向发生,个体以F1代个体为主,尚未脱离亲本独立成种。野外传粉生物学初步观察发现:秋海棠的主要访花昆虫为食蚜蝇类,其次是蜜蜂科,但各自传粉特点及效率尚待进一步研究。杂种及疑似亲本的鉴定可通过形态学、分子生物学和人工重复杂交等综合方法实现。杂种的基因组大小(C值)等于或接近两亲本的平均值,误差通常小于10%,有助于辅助鉴定杂种及亲本。我们总结后认为杂交发生及杂种形成必须满足5个条件:(1)重叠或邻近分布;(2)花期相遇;(3)有效传粉媒介;(4)杂交亲和;(5)适宜种子萌发幼苗生长的小生境及气候条件。据此,我们预测了国产秋海棠属未来可能发生的约40个新杂交组合的可能亲本及地点。到目前为止,尽管所有已知的秋海棠杂种尚未形成真正的新物种,但是,为了满足科学研究及实践交流的需要,建议按照新分类群发表的严格要求,将"杂种"逐一开展调查研究并整理发表,并将其作为物种进化过程中的一个特殊分类单元对待。鉴于秋海棠属的杂种个Natural hybridization is a very common phenomenon in plants and has continuously been a hot- spot in the scientific research of speciation and evolution. As one of the largest genera in plants, Begonia has a large number of species. However, very few cases have been reported on its natural hybrids. A systematic investigation of natural hybridization of Begonia can not only improve understanding of plant diversity and germplasm resources of this genus, but also be a step towards solving its taxonomical issues. Through a comprehensive field survey and experimental analysis of natural hybridization in Chinese begonias, we foundnearly 50 populations of 31 natural hybrids occurred among 29 species, accounting for 15% of currently about 200 accepted species. Begonia hemsleyana and B. longifolia had the highest cross frequency and crossed with 8 and 7 other species, respectively. B. palmata contributed to 16 hybrid populations, the largest number in all individual species. The largest number of hybrids （31 hybrid populations from 20 parental spe- cies） occurred in Yunnan （mainly in the southern areas）, followed by Taiwan and Guangxi. Hybridization between species was unidirectional in most cases, and the majority of hybrids were F1 individuals, which still rely on parents or hybridization zones and have not been established as a true species. Field observations showed that aphid flies, followed by members of the bee family （Apidae）, were the most frequent visitors of begonia flowers, however, further studies are necessary to examine their behavior and the efficiency of polli- nation. The natural hybrids and their putative parents were identified using integrative methods of morphol- ogy, molecular research, and artificial crossing experiments. Genome size （C value） of hybrids was usually equal or close to the average of that of the two parents, with an error less than 10%, which could assist iden- tification of hybrids and parents. In addition, we summarized the five conditions necessary for the occurren

关 键 词：秋海棠属 自然杂交 发生频率 特殊分类单元 杂交方向 传粉 

分 类 号：Q943[生物学—植物学]