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Bulletin of Botanical Research ›› 2020, Vol. 40 ›› Issue (5): 648-658.doi: 10.7525/j.issn.1673-5102.2020.05.002

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Adaptive Differentiation of NBA1/MERIT40 of Three Species of Hippophae L.——Discussion on the Application of Next-generation Sequencing Technology in Hybrid Identification

SUN Kun, DING Xue-Yang, ZHANG Hui, LI Xue-Li, WANG Ying, WANG Juan, LIU Ben-Li   

  1. College of Life Science, Northwest Normal University, Lanzhou 730070
  • Received:2019-11-20 Online:2020-09-05 Published:2020-07-10
  • Supported by:
    Under the auspices of the National Natural Science Foundation of China(30660060)

Abstract: With the development of high-throughput sequencing technology, the study of molecular mechanisms of adaptive evolution in the "Omics" level has become a hotspot of evolutionary research. In this study, transcriptome sequencing was carried out using materials of Hippophae rhamnoides ssp. sinensis, H.neurocarpa and H.goniocarpa that is a hybrid species from homoploid hybridization between the former two species, and the gene of subunit NBA1 of BRA1-A&BRISC complex was selected to deeply study on the basis of its positive selection(w>1). Bioinformatics analysis found that the coding region of NBA1 gene was 771 bp in three sea buckthorns in length, which was a nuclear localized hydrophilic protein that encoding a total of 256 amino acids. The amino acid sequence of NBA1 of H.rhamnoides ssp. sinensis and H.neurocarpa have different loci which is loci of 218 and 236. The site of 218 which close to ligand binding sites in H.rhamnoides ssp. sinensis is different from the VWA domain of H.neurocarpa and terrestrial plants, and it has been mutated from conserved leucine to methionine. This resulted in a significant change in the protein tertiary structure of H.rhamnoides ssp. sinensis and H.neurocarpa, and makes the protein binding sites have significant difference in spatial structure. Above all, we speculated that the NBA1 subunits differ in binding to another subunit. Mainly led to the difference in the BRCA1-A complex repair DNA damage repair function that caused by UV radiation, and it may be related to the adaptation of H.rhamnoides ssp. sinensis and H.neurocarpa to different elevations. In addition, Sanger sequencing has verified the accuracy of the next generation sequencing results, and has proved that is a homozygous gene of single copy in two parental species H.rhamnoides ssp. sinensis and H.neurocarpa, and exists in codominant allele way in H.goniocarpa. Further analysis found that the next generation sequencing data is not suitable for identifying hybrids at the level of individual, but it can reflect the parental source of the hybrid randomly to some extent if we parallel sequencing in multiple individuals within the populations. This study provides a reference data for further revealing the molecular mechanism of adaptation of Hippophae L. to different altitudes, and proposes advice in choose transcriptome sequencing methods to identify hybrid species.

Key words: NBA1, Hippophae rhamnoides ssp. sinensis, H.neurocarpa, H.goniocarpa, adaptive differentiation, hybrid identification

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