Definition of Eight Mulberry Species in the Genus Morus by Internal Transcribed Spacer-Based Phylogeny

PLoS One. 2015 Aug 12;10(8):e0135411. doi: 10.1371/journal.pone.0135411. eCollection 2015.

Abstract

Mulberry, belonging to the order Rosales, family Moraceae, and genus Morus, has received attention because of both its economic and medicinal value, as well as for its important ecological function. The genus Morus has a worldwide distribution, however, its taxonomy remains complex and disputed. Many studies have attempted to classify Morus species, resulting in varied numbers of designated Morus spp. To address this issue, we used information from internal transcribed spacer (ITS) genetic sequences to study the taxonomy of all the members of generally accepted genus Morus. We found that intraspecific 5.8S rRNA sequences were identical but that interspecific 5.8S sequences were diverse. M. alba and M. notabilis showed the shortest (215 bp) and the longest (233 bp) ITS1 sequence length, respectively. With the completion of the mulberry genome, we could identify single nucleotide polymorphisms within the ITS locus in the M. notabilis genome. From reconstruction of a phylogenetic tree based on the complete ITS data, we propose that the Morus genus should be classified into eight species, including M. alba, M. nigra, M. notabilis, M. serrata, M. celtidifolia, M. insignis, M. rubra, and M. mesozygia. Furthermore, the classification of the ITS sequences of known interspecific hybrid clones into both paternal and maternal clades indicated that ITS variation was sufficient to distinguish interspecific hybrids in the genus Morus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA, Ribosomal Spacer*
  • Morus / classification
  • Morus / genetics*
  • Phylogeny*
  • RNA, Ribosomal, 5.8S / genetics

Substances

  • DNA, Ribosomal Spacer
  • RNA, Ribosomal, 5.8S

Grant support

The National Natural Science Foundation of China (31201005), Scientific and Technical Assistance Project in Xingjiang (2013911102) and Scientific Research Fund for Doctor of Southwest University (swu1111080) for data collection and analysis, the Fundamental Research Funds for the Central Universities (XDJK2014C050) for data analysis, National Hi-Tech Research and Development Program of China (2013AA100605-3) for decision to publish.