Interfered chromosome pairing at high temperature promotes meiotic instability in autotetraploid Arabidopsis

High temperature increases meiotic instability in newly generated autotetraploid Arabidopsis thaliana by interfering with chromosome pairing. Changes in environmental temperature affect multiple meiotic processes in flowering plants. Polyploid plants derived from whole-genome duplication (WGD) have enhanced genetic plasticity and tolerance to environmental stress but face challenges in organizing and segregating doubled chromosome sets. In this study, we investigated the impact of increased environmental temperature on male meiosis in autotetraploid Arabidopsis (Arabidopsis thaliana). Under low to mildly increased temperatures (5 degrees C-28 degrees C), irregular chromosome segregation universally occurred in synthetic autotetraploid Columbia-0 (Col-0). Similar meiotic lesions occurred in autotetraploid rice (Oryza sativa L.) and allotetraploid canola (Brassica napus cv Westar), but not in evolutionarily derived hexaploid wheat (Triticum aestivum). At extremely high temperatures, chromosome separation and tetrad formation became severely disordered due to univalent formation caused by the suppression of crossing-over. We found a strong correlation between tetravalent formation and successful chromosome pairing, both of which were negatively correlated with temperature elevation, suggesting that increased temperature interferes with crossing-over predominantly by impacting homolog pairing. We also showed that loading irregularities of axis proteins ASY1 and ASY4 co-localize on the chromosomes of the syn1 mutant and the heat-stressed diploid and autotetraploid Col-0, revealing that heat stress affects the lateral region of synaptonemal complex (SC) by impacting the stability of the chromosome axis. Moreover, we showed that chromosome axis and SC in autotetraploid Col-0 are more sensitive to increased temperature than those in diploid Arabidopsis. Taken together, our data provide evidence suggesting that WGD negatively affects the stability and thermal tolerance of meiotic recombination in newly synthetic autotetraploid Arabidopsis.

Automated summary

High temperature interferes with chromosome pairing and increases meiotic instability in newly generated autotetraploid Arabidopsis thaliana. The impact of increased environmental temperature on male meiosis in autotetraploid plants was investigated. The study found that temperature elevation disrupts proper chromosome segregation and tetrad formation, mainly by interfering with homolog pairing and suppressing crossing-over. Furthermore, the stability of the chromosome axis is affected by heat stress. These findings highlight the negative effects of whole-genome duplication and high temperature on the stability and thermal tolerance of meiotic recombination in autotetraploid plants.