Longli is not a Hybrid of Longan and Lychee as Revealed by Genome Size Analysis and Trichome Morphology

Robert VanBuren, Jianguo Li, Francis Zee, Jianhua Zhu, Chengming Liu, Aru K. Arumuganathan, Ray Ming

Research output: Contribution to journalArticlepeer-review

Abstract

Lychee, longan, longli, and rambutan are closely related, commercially important fruit trees in the Sapindaceae family. Longli fruits are morphologically similar to both lychee and longan, displaying a yellow-brown pericarp like longan, and small, sharp protuberances like lychee. These similarities have led to the hypothesis that longli is the result of intergeneric hybridization between longan and lychee. Scanning electron microscopy and flow cytometry were used to examine trichome morphology and genome size, respectively, to test this hypothesis. Longan, lychee, longli (D. confinis), and 'Malesianus' (D. longan sub spp malesianus) had morphologically distinct trichomes. The genome sizes for lychee (554 Mb), longan (444 Mb), 'Malesianus' (404 Mb), and rambutan (339 Mb) are distinctive and in a narrow range. 'Malesianus' has a genome 9% smaller than that of longan and 27% smaller than that of lychee. It is likely a species that evolved independently in northern Borneo island, and could be classified as a species, Dimocarpus malesianus, not a sub-species of longan as presently stated. Flow cytometry revealed a 50% variation in genome sizes among longli varieties, with genome sizes ranging from 450 to 678 Mb, beyond the range between longan and lychee. The genome size variation and distinct leaf hair morphology suggest that longli is not an intergeneric hybrid, and it is likely a separate genus evolved independently. The tested cultivars with distinctive genome sizes within D. confinis could be classified as separate species.

Original languageEnglish (US)
Pages (from-to)228-236
Number of pages9
JournalTropical Plant Biology
Volume4
Issue number3-4
DOIs
StatePublished - Dec 2011

Keywords

  • Flow cytometry
  • Intergeneric hybridization
  • Longli
  • Nuclear DNA content
  • Scanning electron microscopy

ASJC Scopus subject areas

  • Genetics
  • Plant Science

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