Investigation On History, Culture,Germplasm And Phylogeography Of Begonia Grandis Dry

Begonia grandis Dryand. belongs to Begoniaceae. It has a long history in Chinese literature and cultivation due to its high values as an ornamental, medicinal, edible and cultural plant. B. grandis is the most northerly distributed, strongest cold-resistant, one of the widest distribution species and the only species developing tubers in leaf axils of aerial stems in Begoniaceae. Therefore, it is also especially important in scientific research. However, the distribution, germplasm and conservation status of this species have not been well understood before. Classification of B. grandis subspecies is unreasonable based on both Flora Republicae Popularis Sinicae and Flora of China since their existing criteria don’t work in practice. Therefore, the status of intraspecific taxa remains unclear. In order to better understand, protect and utilize B. grandis, the history, culture, utilization, classification, distribution, germplasm diversity were investigated, summarized and discussed in this study, through a comprehensive review on literature and worldwide specimens, field survey as well as review on the online living plants images of this species from the websites of Chinese Natural Herbarium, Google.com, etc. Meanwhile,352individuals of44wild B. grandis populations from all native regions except Tibet were used as material to investigate its intraspecific diversity and phylogeography based on analysis of the three chloroplast genes, ndhF-rpl32, atpl-atpH and ndh A intron. The results show as follows:1. B. grandis has a long history record of cultivation dating back to Song Dynasty. Its medicinal use can be dated back to Supplements Compendium of Materia Medica (Xuemin Zhao,1765). B. grandis has a high cultural value and was widely used in verses and prose fictions by the scholars in the early dynasties. Also, it could be found in traditional Chinese paintings, porcelain and sculptural arts.2. B. grandis is only native to China. Through literature and specimen review and field survey, its native distribution range and distribution provinces are accurately determined by our study for the first time. The altitude is from ca.75m to3400m with the lowest location at Shanjuandong of Jiangsu and the highest at Haba Snow Mountain of Yunnan. The distribution longitude ranges from97°27’34"E to121°47’15"E, and the latitude from22°59’19"N to40°40’05"N. Binggou of Hekanzi in Lingyuan of Liaoning is the northern boundary, and Pingbian County of Yunnan is the southern boundary; Qinnathon of Chawa Long in Chayu County of Tibet is the western boundary, and Tiantong National Forest Park in Ningbo of Zhejiang is the eastern boundary. Compared with the record in Flora of China, six provinces (municipal cities and autonomous regions) were added to distribution map, namely Chongqing, Guangdong, Jiangsu, Liaoning, Tianjin and Tibet. The wild plants of B. grandis were recently discovered in a mountain of central Taiwan, but further investigation is necessary on its native or naturalized status. In addition, this species was introduced into Japan in the Edo period (1624-1644) and now has been widely naturalized in Japan.3. After a preliminary survey on24chloroplast DNA fragments, we obtained3phylomophic fragments suitable for analysis of B. grandis, ndhF-rpl32, atpl-atpH. and ndhA intron, with a length of723bp,731bp and708bp, respectively. The46variation sites and35cpDNA haplotypes were discovered, among which,28haplotypes were unique and found in23pupulations. A high relative level of genetic diversity was observed in B. grandis. The whole genetic diversity (Hd) is0.910and haplotype diversity (Hd) is0.894. AMOVA analysis showed that83.52%of genetic variation existed among populations with genetic differentiation coefficient FST=0.835. According to chloroplast haplotype Network, SAMOVA and BEAST analysis,44B. grandis groups can be divided into three branches:Group1(mainly located in Eastern China area), Group2(mainly in the southwest region) and Group3(mainly in the north of Yangtze river).4. The inconsistence of group division between molecular data and morphological results could be explained by the following possible reasons:the morphological evidence provided by both Flora Republicae Popularis Sinicae and Flora of China on B. grandis may be not established; the infraspecific unit of B. grandis could not be divided well due to the possible insufficient information of cpDNA fragments; high frequency of gene flow between groups occurred and resulted in a complex relationship of infraspecies.5. Genetic diversity and nested clade analysis of cpDNA haplotypes revealed that B. grandis had several refuges during the Quaternary, such as the Hengduan mountains, Qin-Ba mountains and Nanling region.