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

Abstract

Natural hybridization has been considered a source of taxonomic complexity in Cryptocoryne. A combined study of DNA sequencing data from internal transcribed spacer (ITS) of nuclear ribosomal DNA and trnK-matK region of chloroplast DNA was used to identify the parents of Cryptocoryne putative hybrids from Peninsular Malaysia. Based on the morphological intermediary and sympatric distribution, the plants were tentatively identified as the hybrid Cryptocoryne xpurpurea nothovar. purpurea; plants were pollen sterile and had long been considered to be hybrids, possibly between two related and co-existing species, C. cordata var. cordata and C. griffithii. The C. xpurpurea nothovar. purpurea status was independently confirmed by the presence of an additive ITS sequence pattern from these two parental species in hybrid individuals. 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.