Chromosome numbers of Carex (Cyperaceae) and their taxonomic implications

Abstract

Counting chromosomes is the first step towards a better understanding of the karyotype evolution and the role of chromosome evolution in species diversification within Carex; however, the chromosome count is not known yet for numerous sedges. In this paper chromosome counts were performed for 23 Carex taxa from Armenia, Austria, the Czech Republic, and Poland. Chromosome numbers were determined for the first time in three species (Carex cilicica, 2n = 54; C. phyllostachys, 2n = 56; C. randalpina, 2n = 78), two subspecies (C. muricata subsp. ashokae, 2n = 58; C. nigra subsp. transcaucasica, 2n = 84) and two hybrids (C. ×decolorans, 2n = 74; C. ×walasii, 2n = 108). Among the taxa whose number of chromosomes had been known before, the largest difference was found in C. hartmaniorum (here 2n = 52) and C. aterrima subsp. medwedewii (here 2n = 52). A difference in the chromosome count was demonstrated for C. cilicica (2n = 54) versus the species of the section Aulocystis (2n = 30 to 40) and for C. tomentosa (2n = 48) versus the species of the section Acrocystis (2n = 18 to 38). The results of this study indicate that the position of C. cilicica in Aulocystis section may raise doubts. Attention was paid to the relationship between C. phyllostachys and taxa of the subgenus Carex section Gynobasidae.

Meiosis Progression and Recombination in Holocentric Plants: What Is Known?

“…In the Cyperaceae family, which is the largest group of holocentric plants, chromosomes vary from n = 2 to n = 108 (Roalson, 2008). Although the lowest chromosome number in angiosperms is found in Rhynchospora tenuis (n = 2), we can also find extraordinarily very high chromosomes numbers in other genera within this family, for instance in Carex (Wieclaw et al, 2020) and Cyperus (Roalson, 2008). Since the number of chromosomes is proportional to recombination rates, high chromosome numbers would also impose higher recombination rates in holocentric plants, specially, in this case where the number of chiasmata tends to be typically low, with one or two CO per bivalent.…”

Hybrid enrichment of adaptive variation revealed by genotype–environment associations in montane sedges

“…Meiotic aberrations are also quite common in Carex and can cause these taxa to behave unlike most other angiosperms, especially with regard to hybridization (Hipp, 2007). There are no chromosome count data available for either of the parental species; counts in the genus range from n = 6–62 (Więcław et al, 2020), limiting our ability to consider the viability of this alternative explanation for the outlier loci. However, it seems peculiar that we observed a similar number of loci with extreme ancestry for each parent; this is consistent with a drift hypothesis, but the environmental association of outlier loci and their position in environmental space makes this unlikely.…”

Morphological variability and genetic diversity in Carex buxbaumii and Carex hartmaniorum (Cyperaceae) populations

“…buxbaumii , and 2n = 52, 68 for C . hartmaniorum (see Więcław, Kalinka & Koopman, 2020 ). Generally, polyploidy in Carex is relatively rare and is fairly difficult to find due to chromosomal traits (i.e., holocentric chromosomes) ( Hipp, Rothrock & Roalson, 2009 ).…”

“…Lipnerová et al (2013) demonstrated that a substantial increase in the chromosome count (mostly doubling) corresponded with a concomitant increase in the genome size in the sections Clandestinae and Racemosae; in the latter, the genome size and the chromosome counts in C. buxbaumii and C. adelostoma were almost twice those in C. aterrima, C. parviflora, C. atrata, C. norvegica and C. hartmaniorum. Moreover, the species were referred to as having different cytotypes; mainly 2n = 100, 102, 106 for C. buxbaumii, and 2n = 52, 68 for C. hartmaniorum (see Więcław, Kalinka & Koopman, 2020). Generally, polyploidy in Carex is relatively rare and is fairly difficult to find due to chromosomal traits (i.e., holocentric chromosomes) (Hipp, Rothrock & Roalson, 2009).…”