Molecular evidence for natural hybridization in the mangrove fern genus Acrostichum

BMC Plant Biology

Research Article

Yunqin Li¹  Wei Wu²  Ting Liu³  Lishi Huang³  Suhua Shi³  Yelin Huang³  Lifang Chao³  Rongshu Zhang³  Renchao Zhou³ 

[1] Experimental Center of Fundamental Teaching, Zhuhai Campus, Sun Yat-sen University, 519802, Zhuhai, China;Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, 510650, Guangzhou, China;State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, Sun Yat-sen University, 510275, Guangzhou, China;

关键词: Acrostichum;    Chloroplast DNA;    Ferns;    Mangroves;    Natural hybridization;    Nuclear genes;   

DOI  :  10.1186/1471-2229-13-74

 received in 2012-09-06, accepted in 2013-04-26,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundNatural hybridization is prevalent in ferns, and plays an important role in fern evolution and speciation. In the Indo West-Pacific region, the mangrove fern genus Acrostichum consists of two largely sympatric species, A. aureum and A. speciosum. Although there has been no report of interspecific hybridization before, we found some individuals morphologically intermediate between them in Guangdong and Hainan, China, for the first time, which were suspected to be hybrids. In this study, we aimed to test the hypothesis of natural hybridization between A. aureum and A. speciosum in Guangdong and Hainan using three low-copy nuclear genes. A chloroplast intergenic spacer was used to infer the hybridization direction once the hybrid status was confirmed. In addition, we examined spore shapes and germination for these taxa.ResultsBoth A. aureum and A. speciosum showed a low level of polymorphism at all three nuclear genes; however, they were well separated at these loci. At both locations, each individual of the putative hybrid showed additivity in chromatograms at all sites where the two species showed fixed differences. Haplotype analysis at all three nuclear genes indicated that each individual of the putative hybrid possessed two haplotypes, matching with those of A. aureum and A. speciosum, respectively. Sequencing of the chloroplast trnV-trnM regions showed that A. aureum differed from A. speciosum by eleven nucleotide substitutions and three indels (insertions/deletions), and all sampled individuals of the putative hybrid had the identical sequences with A. speciosum. Compared with A. aureum and A. speciosum, the putative hybrid had much reduced spore germination rate.ConclusionsSequence data of the three nuclear genes provide compelling evidence for natural hybridization between A. aureum and A. speciosum, and all the hybrid individuals are likely F1s. The hybridization is unidirectional and A. speciosum is the maternal parent of the hybrid based on the assumption of maternal inheritance of chloroplast DNA. Human disturbance on mangrove habitats may facilitate the establishment of hybrids of Acrostichum.

【 授权许可】

Unknown   
© Zhang et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.