Cytogeography and chromosomal variation of the endemic East Asian herb Lycoris radiata

Abstract

Information on the spatial distribution of cytotypes and karyotype variation in plants is critical for studies of the origin and evolution of polyploid complexes. Here, the spatial distribution of cytological races and intraspecific variation in the karyotype of Lycoris radiata, an endemic species to East Asia, is investigated. Conventional karyotype analysis methods were used to determine ploidy level and karyotypical characteristics in 2,420 individuals from 114 populations of L. radiata nearly covering the whole distribution areas in China. Of 114 populations studied, 52 (45.61%), 58 (50.88%), and 4 (3.51%) are diploid, triploid, and mixoploid populations, respectively, with 1,224, 1,195, and 1 individuals being diploid, triploid, and tetraploid, respectively. The triploid possesses a much wider distribution range than the diploid, with the former almost occupying the entire range of this complex species in East Asia and the latter distributing in the middle and east regions of China. Triploids tend to occur at high altitudes, and the relationship between the ploidy and altitude is significantly positive but low (r2 = 0.103, p < 0.01). About 98.6% of examined bulbs have a common karyotype consisting of 22 or 33 acrocentric (A) chromosomes. Some aberrant chromosomes which should be generated from A‐type chromosome have been found including metacentrics (m), small metacentrics (m′), and B‐type chromosome. The results can provide a fundamental cytogeographic data for further studies on the evolutionary origins and adaptive divergences of polyploids, especially the triploid, within L. radiata using molecular and/or ecological methods in the future.

Chromosomal variations of Lycoris species revealed by FISH with rDNAs and centromeric histone H3 variant associated DNAs

“…Plants with karyotype 2n = 33, 31A+1M’+m have been identified in several populations with standard karyotype 2n = 33A [ 37 , 38 ]. In several Lycoris species, in some cases, the small chromosomes were considered B or supernumerary chromosome [ 2 , 4 , 35 , 38 – 40 ]. As we showed here, the m chromosome with 45S rDNA and telomeres ( Fig 1A–1C ) was evenly segregated to daughter cells in anaphase ( Fig 1D ) and so considered as an intact chromosome with a functional centromere.…”

“…Lycoris species feature diverse chromosome number and morphology [ 2 ]. The chromosome numbers of Lycoris species range from 2n = 12 to 44, including diploid, triploid, tetraploid and aneuploid [ 3 , 4 ]. The chromosome complement of Lycoris species may contain three fundamental types, including metacentric (M), telocentric (T), and acrocentric (A) chromosomes [ 2 ].…”

Comparative genomics and phylogenetic perspectives of six fertile Lycoris species endemic to East Asia based on plastome characterization

“…7 (Katoh and Standley 2013), we extracted protein coding regions, introns and intergenic spacers to explore the highly variable regions in Lycoris for future genetic diversity analysis and species identification under the criteria that aligned length is > 200 bp. For validating the effectiveness of highly variable regions at a population-level, eight populations (two individuals for each population) from our previously collected L. radiata populations were selected (Supporting information) (Liu et al 2019). Total genomic DNA were extracted from fresh leaf materials using the modified 2× CTAB method.…”

“…and the chromosome number of L. radiata has been found to be 21, 22, 32, 33 and 44, etc. (Liu et al 2019). To date, no detailed comparative genomic analysis of Lycoris has been carried out.…”

Divide to Conquer: Evolutionary History of Allioideae Tribes (Amaryllidaceae) Is Linked to Distinct Trends of Karyotype Evolution

“…The search for the causes of species geographic distributions is notable for its lack of universally applicable rules (Stebbins, 1971;Lowry and Lester, 2006;Araújo et al, 2019;Liu et al, 2019). The current species distribution reflects their dispersal ability, environmental tolerance, niche breadth, population abundance, colonization-extinction dynamics, and character diversity (Brown et al, 1996;Lowry and Lester, 2006).…”