Genetic diversity patterns in Curcuma reflect differences in genome size

Abstract

The relationships between genome size and the systematic and evolutionary patterns in vascular plants are equivocal, although a close relationship between genome size and evolutionary patterns has been previously reported. However, several studies have also revealed the dynamic nature of genome size evolution and its considerable 'ups' and 'downs'. Thus, in this study, the phylogenetic relationships among three previously revealed genome size groups and among species of the highly polyploid genus Curcuma were evaluated using AFLP. Our results suggest two main lineages within Indian Curcuma reflecting evolution of genome size. The first one includes hexaploids and higher polyploids of the previously recognized genome size group I, and the second one includes mainly hexaploids of genome size groups II and III. Within genome size group I, relationships among species seem to be influenced by reticulate evolution and higher polyploids are likely to be of allopolyploid origin. Reproductive systems in Indian Curcuma vary considerably among ploidy levels and these differences considerably affect morphological and genetic variation. In general, clonally reproducing species are expected to exhibit low genotypic diversity, but, at the same time, species of allopolyploid origin are expected to maintain higher levels of heterozygosity compared with their progenitors. We investigated intra-populational genetic variability in Curcuma spp. to evaluate whether mode of reproduction or ploidy represent the main factor influencing the degree of genetic diversity. We found that hexaploid species exhibited significantly higher genetic diversity than higher polyploids (9x, 15x). Our results suggest that this genetic diversity pattern is largely influenced by the mode of reproduction, as higher polyploids reproduce exclusively vegetatively, whereas hexaploids reproduce mainly sexually.

Prospects for discriminating Zingiberaceae species in India using DNA barcodes

“…Divergent ribosomal DNA sequences arise in hybrids due to differences in the evolutionary trajectories of parental sequences during the process of concerted evolution (Alvarez and Wendel ; Bailey et al ). Thus, the results of the present study and previous studies (Leong‐Skornickova et al ; Zaveska et al , ) clearly indicate that Curcuma species are the products of recent hybridization events wherein the concerted evolution of ITS is at an initial phase and the ancestral haplotype of the plastid persists, affecting the barcode potential of both plastid and ITS loci.…”

Chromosome number variation and polyploidy in 19 Kaempferia (Zingiberaceae) taxa from Thailand and one species from Laos

“…A sexual mode of reproduction is a known mechanism for maintaining high genetic diversity within species. For the genus Curcuma (Zingiberaceae), Záveská et al () found that Nei's gene diversity in sexually‐reproducing diploid taxa is significantly greater than in vegetatively‐reproducing (triploid and pentaploid) taxa. Based on chloroplast DNA sequence divergence (Techaprasan et al, ), this appears to be the case for Kaempferia as well.…”

The origin of unique diversity in deglaciated areas: traces ofPleistocene processes in north‐European endemics from theGalium pusillumpolyploid complex (Rubiaceae)

“…) was carried out for 403 individuals using the AFLP Core Reagent Kit I (Invitrogen) and the AFLP Pre‐Amp Primer Mix I (Invitrogen) following the manufacturer's instructions, with modifications described in Záveská et al . () and as follows: DNA (~40 ng) was digested for 12 h at 37 °C with 0.6 U each of EcoRI and MseI (Invitrogen) and 1 μL 5× reaction buffer (Invitrogen) in a total volume of 5 μL. Adaptors were ligated to the digested fragments by adding 4.8 μL adaptor/ligation solution (Invitrogen) and 0.3 U T4 DNA ligase (Invitrogen), and the reaction (total volume 10 μL) was incubated for 12 h at 37 °C.…”