Meiotic behaviour in natural diploid, tetraploid, and commercial diploid crested wheatgrass

Abstract

Chiasma frequencies and chromosome associations at diakinesis and first metaphase (MI) were studied in natural and commercial diploid Agropyron cristatum and natural tetraploid Agropyron desertorum crested wheatgrass plants. The frequencies of bivalents were 6.988 and 6.980 at diakinesis and 6.980 and 6.976 at MI in the natural and commercial diploids, respectively. The frequencies of bivalents and quadrivalents in the natural tetraploid were 7.728 and 3.072 at diakinesis, and their frequencies at MI were 7.880 and 2.984, respectively. A few univalents were formed at diakinesis and MI in the three crested wheatgrasses, and these were generally associated with trivalents at the two stages in the tetraploid. There were positive and significant correlations between the frequencies of chiasmata at diakinesis and those of chiasmata at MI in the three crested wheatgrasses. Tetraploid A. desertorum, in particular, is thought to be an important breeding material for future studies when growth performance and meiotic regularity are taken into consideration.

Varietal variation and chromosome behaviour during meiosis in Solanum tuberosum

“…Alternatively, an evolved autotetraploid state may feature a high rate of quadrivalent formation in metaphase I, indicating chiasma formation between more than two homologues (Bomblies et al 2016 ). For example, in various species from purple yam (Abraham et al 2013 ) to peavines (Khawaja et al 1997 ) and various grasses (Koul et al 1999 ; Deniz and Dogru 2006 ), quadrivalent formation at metaphase I reaches 20–47%. A more extreme example is cock’s foot, in which the chromosomes mostly form quadrivalents, and the chiasma frequency in evolved autotetraploids is higher than in the diploids or newly formed tetraploids (McCollum 1958 ).…”

A tetrasomic inheritance model and likelihood‐based method for mapping quantitative trait loci in autotetraploid species

“…H2017 represents the method described in Hackett et al (2017). Quadrivalent chromosomal pairing has been observed in various autotetraploid plants, with a frequency varying from up to 10% in kiwi (Wu et al, 2014), 20-30% in potato (Bourke et al, 2015), and up to 36% in Pennisetum orientale (Deniz & Dogru, 2006). In these cases, bivalent-based methods cannot deal with the full spectrum of the data because there will be a large proportion of observed data that is incompatible with the expected distribution under the bivalent pairing assumption.…”