Synaptonemal complex formation and metaphase I bond distribution at low temperatures in nullisomic 5D – tetrasomic 5B hexaploid wheat

Abstract

Nullisomic 5D – tetrasomic 5B wheat plants were grown at 20 and 16 °C, and the level of paired and unpaired lateral elements in synaptonemal complex (SC) spreads was quantified in early-mid prophase I cells to ascertain the origin of the low frequency of metaphase I associations observed in plants held at 16 °C in the absence of the Ltp1 gene located on the long arm of chromosome 5D. The distribution of chromosome arm associations in metaphase I cells was studied using the C-banding technique. The results obtained confirm that asynapsis was the main cause of the reduction in the level of association in metaphase I at low temperature. Although a nonrandom distribution of chromosome arm associations at metaphase I was observed at both temperatures, this tendency was more visible at 16 °C, leading to the suggestion that at low temperatures differences in the specific ability of chromosome arms to form SCs and chiasmata are enhanced.Key words: synaptonemal complex, Ltp1 gene, metaphase I bonds, wheat, C-banding.

Assessing the Heat Tolerance of Meiosis in Spanish Landraces of Tetraploid Wheat Triticum turgidum

“…The temperature-sensitive stage occurred in the premeiotic interphase, prior to DNA synthesis [40]. The chiasma number reduction is a result of synapsis failure occurred in zygotene [38,41]. The meiotic recombination gene Dmc1 located on chromosome 5D has been identified as a candidate for the maintenance of normal chiasma frequency at low and possibly high temperatures in hexaploid wheat [42].…”