Meiotic behaviour and karyotype features of endangered endemic fodder speciesHedysarum perrauderianum(Fabaceae) in some populations from Algeria

Abstract

The Mediterranean basin is considered to be one of the 33 mega biodiversity hotspots with the greatest number of endemic plants. This region has been exposed to a prolonged anthropogenic influence rendering its biodiversity prone to a rapid change. The first cytogenetic data are presented for Hedysarum perrauderianum Coss. and Durieu (Fabaceae), an endangered stenoendemic fodder species from Algeria. Karyotype features, heterochromatin organization, physical mapping of rRNA genes and meiotic behaviour were studied in six native populations. The transcriptional rDNA activity was evaluated by nucleoli number. The tetraploid chromosome number 2n = 4x = 32 was found in all populations studied. However, in two roadside populations we observed cells of the same individuals that had 32 and 18 chromosomes. Constitutive heterochromatin is mainly present in intercalary and telomeric positions. Four strong GC-rich DNA bands situated on two pairs of satellite chromosomes are colocalized with 18S-5.8S-26S rDNA loci. Sixteen additional weak CMA bands are also observed in centromeric regions. FISH revealed two loci of both 18S and 5S rDNA, distributed on different chromosome pairs. The similarity of certain chromosome pairs (morphological type of chromosome, constitutive heterochromatin) and presence of univalents, trivalents and tetravalents suggest an autotetraploid origin of this species. One to four heterochromatic B chromosomes were also observed in some populations. The frequencies of different types of chromosome pairing and meiotic abnormalities revealed two groups of populations according to environmental conditions.

Molecular Cytogenetics of Eurasian Species of the Genus Hedysarum L. (Fabaceae)

“…Also, variations in the number of 45S rDNA loci were observed in karyotypes of plant species ( Phaseolus vulgaris , Capsicum species, Brassica rapa ) grown in different locations [ 51 , 52 , 53 ]. On the other hand, no variations in number and location of 45S rDNA clusters were earlier revealed among accessions of Hedysarum perrauderianum from different regions of Algeria [ 26 ].…”

“…Hedysarum have the basic chromosome number x = 7 unlike the species from other sections having x = 8 [ 4 , 21 , 25 ]. FISH-based chromosomal localization of rRNA genes was carried out in five Algerian species [ 26 , 27 ]. Molecular cytogenetic analysis of other Hedysarum species has not been conducted, and intra- or interspecific variability in chromosome localization of rRNA genes still remains uncertain.…”

Comparative male meiotic studies in some Indian representative species ofCucumisL. (Cucurbitaceae)

“…Kumar and Singhal (2013) has discussed the occurrence of structural heterozygosity, univalent chromosomes and their apparent effect on chiasma frequency and pollen fertility. Among the group II taxa, some wild species such as C. setosus, C. maderaspatanus, C. silentvalleyii, C. prophetarum and C. hystrix have fewer univalents, and an equal proportion of rod and ring bivalents, indicating the heterozygosity in the genetic makeup between the n = 7 and n = 12 groups Benhizia et al (2013). Further it may be recorded here that our observations on chromosome association of C. sativus and C. mello group are at variance with those of Yadava et al (1984) and Benhizia et al (2013).…”