Christensenia aesculifolia is a morphological distinct but locally rare fern. This fern was recorded only from two limestone forests located in the South Yunnan counties Jinping and Hekou in China. Because of its extreme rarity and very small population size, the Chinese occurrences of Christensenia have been considered as requiring protection. 

In a recent study published in Journal of Plant Research, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) reported critical data on the cytology and plastome from the highly threatened Christensenia occurrences in China for the first time. They generated the first complete plastid genome for the genus and reconstructed the phylogenetic relationships of the Chinese occurrences using rbcL sequences and reevaluated its distribution range. 

Furthermore, they investigated the ploidy level of the Chinese occurrences using a combination of chromosome counts and DNA C-value measures. They also revalued the taxonomic status of the Chinese occurrences by comparing the sequence variations with those recorded in Malay Peninsula. Finally, the conservation status of Christensenia was assessed in the context of its local and global distribution. 

“Our study provided new evidence in cytology, plastid genome, and geographical distribution of the relict fern genus Christensenia. These data are crucial to elucidate the species delimitation and develop protection protocols for sustainable preservation the occurrences in China and adjacent regions by either in situ or ex situ procedures”, said Dr. LIU Hongmei, first author of the study. 

“To our knowledge, it is the first integrative study concerning the taxonomic status and diversity of this threatened Mesozoic relict and molecular living fossil”, added Dr.LIU. 

Contact 

LIU Hongmei Ph.D 

Department of Gardening and Horticulture, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China     

E-mail: liuhongmei@xtbg.ac.cn    

Sporophytes of Christensenia. a, b Living plants cultivated at XTBG. c Rhizome of Christensenia. d Pedately lobed leaf. e Fertile leaf with young synangia. f Fertile leaf with mature synangia. (Images by LIU Hongmei)