Molecular evidence of the hybrid origin of Cryptocoryne ×purpurea Ridl. nothovar. purpurea (Araceae).

Rusly Rosazlina,Niels Jacobsen,Marian Ørgaard,Ahmad Sofiman Othman,Tzen-Yuh Chiang

doi:10.1371/journal.pone.0239499

Rusly Rosazlina, Niels Jacobsen + Show 3 more

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https://doi.org/10.1371/journal.pone.0239499

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Journal: PloS one	Publication Date: Jan 21, 2021
Citations: 1	License type: CC BY 4.0

Affiliation: Universiti Sains Malaysia, University of Copenhagen

Abstract

Natural hybridization has been considered a source of taxonomic complexity in Cryptocoryne. A combined study of DNA sequencing data from the internal transcribed spacer (ITS) of nuclear ribosomal DNA and the trnK-matK region of chloroplast DNA was used to identify the parents of Cryptocoryne putative hybrids from Peninsular Malaysia. Based on the intermediate morphology and sympatric distribution area, the plants were tentatively identified as the hybrid Cryptocoryne ×purpurea nothovar. purpurea. The plants were pollen sterile and had long been considered as hybrids, supposedly between two related and co-existing species, C. cordata var. cordata and C. griffithii. The status of C. ×purpurea nothovar. purpurea was independently confirmed by the presence of an additive ITS sequence pattern from these two parental species in hybrid individuals. An analysis of the chloroplast trnK-matK sequences showed that the hybridization is bidirectional with the putative hybrids sharing identical sequences from C. cordata var. cordata and C. griffithii, indicating that both putative parental species had been the maternal parent in different accessions.

Highlights

Natural interspecific hybridization has been demonstrated to be an important force in forming new species [1, 2] and plays a crucial role in plant evolution and diversification [3, 4]
C. schulzei had identical internal transcribed spacer (ITS) profiles to those of C. cordata var. cordata and C. ×purpurea nothovar. purpurea. This additivity strongly supports the fact that C. ×purpurea nothovar. purpurea is the hybrid of C. cordata var. cordata and C. griffithii, ITS data alone cannot reject the possibility of it being C. griffithii × C. schulzei
The nuclear ITS sequences of C. ×purpurea nothovar. purpurea showed nucleotide polymorphism at some sites, whereas those of C. cordata var. cordata and C. griffithii did not (Table 2); the data from the C. ×purpurea nothovar. purpurea accessions exhibited polymorphism patterns which are consistently formed by additive sequences derived from two hypothesized parental species

Summary

Introduction

Natural interspecific hybridization has been demonstrated to be an important force in forming new species [1, 2] and plays a crucial role in plant evolution and diversification [3, 4]. The occurrence of natural hybridization between different species, is not universal but is concentrated among a limited fraction of plant families and genera [5]. Natural hybridization has been suggested to occur frequently in Cryptocoryne. The genus can be seen as having multiple populations in various river systems and hybridization can be an evolutionary driving force that constantly creates new genotypes that are spread across the ever-changing river systems [6,7,8,9,10]. Not until after 1975 was it realized and accepted that some of the plants were probably interspecific hybrids [17].

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