Abstract
BackgroundDNA sequence composition affects meiotic recombination. However, the correlation between tandem repeat composition and meiotic recombination in common wheat (Triticum aestivum L.) is unclear.ResultsNon-denaturing fluorescent in situ hybridization (ND-FISH) with oligonucleotide (oligo) probes derived from tandem repeats and single-copy FISH were used to investigate recombination in three kinds of the long arm of wheat 5A chromosome (5AL). 5AL535–18/275 arm carries the tandem repeats pTa-535, Oligo-18, and pTa-275, 5AL119.2–18/275 arm carries the tandem repeats pSc119.2, Oligo-18 and pTa-275, and 5AL119.2 arm carries the tandem repeats pSc119.2. In the progeny of 5AL535–18/275 × 5AL119.2, double recombination occurred between pSc119.2 and pTa-535 clusters (119–535 interval), and between pTa-535 and Oligo-18/pTa-275 clusters (535–18 interval). The recombination rate in the 119–535 interval in the progeny of 5AL535–18/275 × 5AL119.2–18/275 was higher than that in the progeny of 5AL535–18/275 × 5AL119.2. Recombination in the 119–535 interval produced 5AL119 + 535 segments with pTa-535 and pSc119.2 tandem repeats and 5ALNo segments without these repeats. The 5AL119 + 535 and 5ALNo segments were localized between the signal sites of the single-copy probes SC5A-479 and SC5A-527. The segment between SC5A-479 and SC5A-527 in the metaphase 5ALNo was significantly longer than that in the metaphase 5AL119 + 535.ConclusionThe structural variations caused by tandem repeats might be one of the factors affecting meiotic recombination in wheat. Meiotic recombination aggregated two kinds of tandemly repeated clusters into the same chromosome, making the metaphase chromosome more condensed. To conclude, our study provides a robust tool to measure meiotic recombination and select parents for wheat breeding programs.
Highlights
IntroductionThe correlation between tandem repeat composition and meiotic recombination in common wheat (Triticum aestivum L.) is unclear
The non-denaturing fluorescence in situ hybridization (ND-FISH) of this study indicated that the signals of Oligo-713 occurred on the pericentromeric region of 5AS arms of all the nine wheat cultivars/lines (Fig. 1)
Oligo-275.1 and Oligo-18 signals appeared on 5AS arms of Mian 1403 (M1403) and Mianmai 43 (MM43), they did not occur on 5AL arms of the two cultivars (Fig. 1)
Summary
The correlation between tandem repeat composition and meiotic recombination in common wheat (Triticum aestivum L.) is unclear. Increasing the chromosomal recombination rate can accelerate new cultivars’ development in common wheat (Triticum aestivum L.). Zou et al BMC Plant Biology (2021) 21:167 triple mutant displayed less recombination [5] These findings indicated that factors other than genes help control meiotic recombination. Reduced DNA methylation at the CG sites increases recombination rate in the euchromatic, but not in the pericentric heterochromatin regions [9]. Common wheat can be used as a reference model to study the role of tandem repeats in chromosomal recombination. Previous studies have indicated a correlation between the wheat chromosomal crossover and gene-rich regions [14,15,16,17,18]. Different aspects of recombination should be considered for common wheat because of allopolyploidy and repetitive sequences [19]
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