Polyploidy in the Ginger Family from Thailand

Abstract

Polyploidy is common in the ginger family Zingiberaceae. The aims of the present paper are (1) to provide a general introduction on species diversity with emphasis on conservation; (2) to highlight the human-use significance of this family, focusing on the two major genera, Zingiber (ginger) and Curcuma (turmeric); (3) to present chromosome number data from 45 natural and cultivated Curcuma taxa from Thailand, of which polyploids are predominant; and (4) to describe our own work on cytotaxonomy of selected Thai Curcuma species. We obtained somatic chromosome numbers from root tips and analysed meiotic chromosome behaviour from flowers. We also used the molecular cytogenetic method of ribosomal gene mapping on chromosomes to infer mechanism of polyploidization and reveal genomic relationships among closely related species. The main results of our cytogenetic studies include the following. The most sought-after medicinal Curcuma cultivars growing on a large-scale basis are secondary triploids, so as taxa in natural habitats that are harvested for local utilisation. These triploids are sexually deficient, due to meiotic pairing abnormalities, but they are propagated asexually via rhizomes. The ribosomal mapping results indicate natural triploidization process via hybridisation, either within populations or across the species boundaries.

Genome sequencing of turmeric provides evolutionary insights into its medicinal properties

“…Genomic polyploidy in members of Curcuma genus is well known from previously reported experimental studies 27,85,86 . In this study, we estimated the ploidy level of C. longa genome using next-generation sequencing (NGS) reads, and showed the triploid nature of C. longa genome, which is also supported by the previous experimental studies 27,28,85,86 . The application of Oxford Nanopore long-reads and 10x Genomics linked read sequencing that has the potential to resolve complex polyploid genomes 87 , helped in successfully constructing the C. longa draft genome of 1.02 Gbp with a decent N50 of 100.6 Kbp.…”

“…According to the Plant DNA c-values database 25 , C. longa genome has an estimated size of 1.33 Gbp with 2n = 63 chromosomes, but a wide range of genome size variation (4C values ranging from 4.30 to 8.84 pg) and chromosome number variation (2n = 48 to 2n = 64) in C. longa was suggested 26 . Recent studies showed evidence for a ploidy level of 3X (2n = 63 chromosomes, basic chromosome number X = 21) 27,28 .…”

A chromosome-scale genome assembly of turmeric provides insights into curcumin biosynthesis and tuber formation mechanism

“…The complex diversity of morphology, chromosome numbers and chromosome sizes in curcuma species indicates that these species have a unique evolutionary history in which polyploid events may play an important role ( Leong-Skornicková et al., 2007 ). Polyploidy is more common in the curcuma and zingiber genus ( Anamthawat-Jónsson and Umpunjun, 2020 ). We identified the polyploidy events in two sequenced Zingiberaceae species, which observed one recent WGD shared between turmeric and ginger.…”

Genomic Designing of Climate Smart Turmeric

“…Ginger which shares the same family along with turmeric is known to have almost similar genome size which is about 1.5Gbp very near to turmeric and so known to have same growth and development cycle apart from medicinal and therapeutic properties. Different turmeric species are known to have changes in their diploid chromosome numbers [30]. India 42 Several turmeric cultivars belonging to same species differ in their diploid chromosome numbers depending the type of species which also effects their medical properties.…”