Genome Size Variation within Species of Chinese Jujube (Ziziphus jujuba Mill.) and Its Wild Ancestor Sour Jujube (Z. acidojujuba Cheng et Liu)

Abstract

One of the most important attributes of a genome is genome size, which can to a large extent reflect the evolutionary history and diversity of a plant species. However, studies on genome size diversity within a species are still very limited. This study aims to clarify the variation in genome sizes of Chinese jujube and sour jujube, and to characterize if there exists an association between genome sizes and geographical variation. We measured the genome sizes of 301 cultivars of Chinese jujube and 81 genotypes of sour jujube by flow cytometry. Ten fruit traits, including weight, vertical diameter, horizontal diameter, size, total acids, total sugar, monosaccharide, disaccharide, soluble solids, and ascorbic acid were measured in 243 cultivars of Chinese jujube. The estimated genome sizes of Chinese jujube cultivars ranged from 300.77 Mb to 640.94 Mb, with an average of 408.54 Mb, with the highest number of cultivars (20.93%) falling in the range of 334.787 to 368.804 Mb. The genome size is somewhat different with geographical distribution. The results showed weakly significant positive correlation (p < 0.05) between genome size and fruit size, vertical diameter, horizontal diameter, and weight in the Chinese jujube. The estimated sour jujube genome sizes ranged from 346.93 Mb to 489.44 Mb, with the highest number of genotypes (24.69%) falling in the range of 418.185 to 432.436 Mb. The average genome size of sour jujube genotypes is 423.55 Mb, 15 Mb larger than that of Chinese jujube. There exists a high level of variation in genome sizes within both Chinese jujube cultivars and sour jujube genotypes. Genome contraction may have been occurred during the domestication of Chinese jujube. This study is the first large-scale investigation of genome size variation in both Chinese jujube and sour jujube, which has provided useful resources and data for the characterization of genome evolution within a species and during domestication in plants.

Haplotype Analysis of Chloroplast Genomes for Jujube Breeding

“…For a long time, the taxonomic status of jujube and sour-jujube has been controversial ( Li et al, 2018 ; Wang et al, 2019 ; Liu M. et al, 2020 ). To address these questions, many studies have been carried using molecular markers to analyze the nuclear genome, including those focusing on the haplotype composition, genetic diversity, and geographical origin of jujube ( Liu et al, 2014 ; Shen et al, 2020 ; Song et al, 2021 ).…”

Determination of Genome Size and Chromosome Number of a Ziziphus Species (Z. mauritiana Lam.) from Eastern Senegal

“…Most of the genomic information on Ziziphus species is related to Z. jujuba, for which the entire genome has been sequenced (Huang et al, 2017;Liu et al, 2014). Genome size variation within two diploid Ziziphus species, Z. jujuba [(2n = 2x = 24) and Z. acidojujuba (2n = 2x = 24)], was reported recently (Wang et al, 2019) (Wang et al, 2019). Factors that can affect plant nuclear DNA include the internal standard used and environmental conditions, so a more comprehensive investigation involving a more diverse Z. mauritiana collection of germplasms consisting of both cultivars, and wild species of all ploidy levels from Asia and Africa, and growing under the same conditions is necessary to assess the extent of this intraspecific variation.…”

“…Molecular tools, including amplified length polymorphism (Singh et al, 2006) and simple sequence repeat (Liang et al, 2019), have been used to assess the genetic diversity of Z. mauritiana accessions, but these studies were generally limited to Asian germplasms. In addition, reports on nuclear DNA content analyses have been published, but these studies were mostly done on Z. jujuba and its wild ancestor, the sour jujube, Z. acidojujuba (Wang et al, 2019). Wu et al (2013) reported a nuclear DNA content of 0.40 to 0.44 pg C-DNA (393.6-429.6 Mb) for Z. jujuba, depending on the cultivar, and 0.45 pg C-DNA for Z. acidojujuba.…”

Pomological Traits and Genome Size of Prunus armeniaca L. Considering to Geographical Origin

“…Some studies predicted that genome size variation could be changing together with fruit size, similar to ploidy levels [12,31,32]. The obtained data were evaluated as possible correlations between relative genome size and pomological traits.…”