Molecular cytogenetic study on the plants of Elymus nutans with varying fertility on the Qinghai-Tibet Plateau

Bo Liu; Xiao-Yan Tao; Quan-Wen Dou

doi:10.1016/j.pld.2021.12.003

Molecular cytogenetic study on the plants of Elymus nutans with varying fertility on the Qinghai-Tibet Plateau

Plant Divers. 2021 Dec 28;44(6):617-624. doi: 10.1016/j.pld.2021.12.003. eCollection 2022 Nov.

Authors

Bo Liu^{1

2

3}, Xiao-Yan Tao^{1

2

3}, Quan-Wen Dou^{1

2}

Affiliations

¹ Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, China.
² Qinghai Province Key Laboratory of Crop Molecular Breeding, Xining, China.
³ University of Chinese Academy of Sciences, Beijing, China.

Abstract

A molecular cytogenetic investigation was conducted on plants of the allohexaploid species Elymus nutans with varying fertility on the Qinghai-Tibet Plateau. Molecular karyotyping revealed that chromosome variants were distributed unevenly among genomes and among different homologue chromosomes in each genome. The plants with varying fertility exhibited significantly higher numbers of chromosome variants than did the normal fertility samples, although both kinds of plants showed the same pattern of high-to-low polymorphism from the Y to St and H genomes. Heterozygosis and karyotype heterozygosity in the plants with varying fertility were 3- and 13-fold higher than those in normal samples, respectively. Significant negative correlations were found not only between seed setting rates and total genome heterozygosity but also between seed setting rates and heterozygosity of each genome in the plants of varying fertility. Chromosome pairing analysis was performed using genomic in situ hybridization in selected plants of different fertility levels. The pairing of chromosomes at meiotic metaphase I was mostly bivalent, although univalent, trivalent, quadrivalent, and other polyvalents also occurred; in addition, chromosome configuration forms and frequencies varied among the studied samples. ANOVA results showed that the average number of ring bivalents in the Y genome was significantly higher than those in the St and H genomes. Significant positive correlations between pollen grain fertility and ring bivalent number were found in the St and H genomes but not in the Y genome. Furthermore, chromosome configuration parameters (total bivalents, numbers of ring and rod bivalents) were found to be significantly correlated with heterozygosity and seed setting rates in the St and H genomes, respectively, but not in the Y genome. It was inferred that the seed setting rate and pollen grain fertility in E. nutans are strongly influenced by the heterozygosity of each genome, but the Y genome differs from the St and H genomes due to chromosome pair alterations. The St and H genomes may contain more chromosome structural variations than the Y genome in E. nutans.

Keywords: Chromosome pairing; Elymus nutans; FISH and GISH; Fertility; Karyotype variation.