Meiosis in Aneuploids of Tetraploid Lathyrus Odoratus and L. Pratensis

Abstract

Meiosis was studied in one hypoploid (trisomic, 2n = 4x -1 = 27) of an induced tetraploid (2n = 28) of Lathyrus odoratus and two hyperploids (single pentasomic, 2n = 4x + 1 = 29 and double pentasomic, 2n = 4x + 1 + 1 = 30, respectively) of an induced tetraploid of L. pratensis. Multivalent frequencies in the aneuploids were high, but the numbers of chiasmata were not sufficient to maintain all pairing configurations till metaphase I. Interstitial chbdsmata were relatively frequent. Chiasma frequencies were considerably reduced in all three aneuploids, compared with the eutetraploids. The two pentasomes (sets of five homologous chromosomes) of the double pentasomic were both present as a quinquivalent more frequently than expected when they would behave independently. The single pentasomic and the trisomic did not deviate much from expected, although, like in the eutetraploids, the multivalent frequencies were considerably higher than corresponds with the assumption that pairing initiation is restricted to the chromosome ends. The conclusion is that aneuploids of Lathyrus at the tetraploid level tend to behave similar to euploids, except that the chiasma frequency is considerably reduced. When maintained in the population their progeny will contain even more aneuploids than the euploids, not only because the aneuploidy will be perpetuated, but also because of lower chiasma frequencies leading to univalent formation.

RETRACTED ARTICLE: Karyotype analysis and identification of extra chromosomes in primary aneuploid stocks of grass pea (Lathyrus sativus L.) by fluorescence chromosome banding

“…Although polyploidy has been studied in Lathyrus spp. (Khawaja et al 1998;Talukdar 2010Talukdar , 2012, mitotic fidelity in aneuploid genomes was not known in grass pea. Characterization of aneuploid chromosomes through molecular karyotyping for the first time in grass pea thus assumes significance.…”

Structural karyotypic variability and polyploidy in natural populations of the South American Lathyrus nervosus Lam. (Fabaceae)

“…The extensive similarity observed in the chromosome morphology, the banding pattern and the mapping of rDNA loci between the additional complements of the polyploid individuals and those of the diploid ones belonging to the same population strongly suggests that 3x and 4x cytotypes may have originated by autopolyploidy. Although interpopulation cytotype polymorphisms in L. palustris and L. pratensis were considered as cases of autopolyploidy (Gutiérrez et al 1994), and allopolyploidy has been suggested for L. venosus (Khawaja et al 1997(Khawaja et al , 1998, the mechanism by which polyploidization occurred in the genus has not been considered yet. In general, it is proposed that polyploids may be formed by somatic chromosome doubling or by sexual polyploidization (Darlington 1965;Harlan and De Wet 1975).…”

“…Those analyses revealed high constancy in the basic chromosome number (x = 7) of the taxa and demonstrated that the genus is largely composed of diploid species. The only recognized polyploid species is L. venosus Müch (2n = 4x = 28) (Sybenga 1995;Khawaja et al 1997Khawaja et al , 1998Yamamoto et al 1984), which is endemic to North America and belongs to the ancestral section Orobus (Kupicha 1983). Two other species have polyploidy but as interpopulation polymorphism.…”

Cytogenetic characterization of induced autotetraploids in grass pea (Lathyrus sativusL.)

“…Different morphological and cytological parameters indicated autopolyploid origin of present tetraploid plants which can be further confi rmed by studying tetrasomic inheritance pattern of different isozyme markers in the present material as suggested by SOLTIS et al, (2007). KHAWAJA et al(1998) used colchicineinduced autotetraploids as valuable source for development and maintenance of different aneuploids including trisomics in other Lathyrus spp. The information gathered from the present study on induced tetraploids could be useful in future improvement of grass pea breeding.…”