Heat stress during male meiosis impairs cytoskeletal organization, spindle assembly and tapetum degeneration in wheat

We demonstrate here that heat stress severely alters the cytoskeletal configuration, cell structure, and global gene expression in male meiocytes and the tapetum layer, in a genotype-dependent manner. 'Ellvis', a heat-tolerant winter wheat cultivar, showed high fertility and only scarce structural aberrations upon exposure to high temperature. In addition, heat shock genes and genes involved in the alleviation of reactive oxygen species were significantly upregulated in 'Ellvis' and the expression of meiosis-specific and important developmental genes showed high stability in this cultivar. In the heat-sensitive Mv 17-09, however, genes participating in cytoskeletal fiber nucleation, the spindle assembly checkpoint (SAC) genes, and tapetum-specific developmental regulators were all downregulated. These alterations may be related to the decreased cytoskeleton content, frequent micronuclei formation, and the erroneous persistence of the tapetum layer observed in the sensitive genotype. Overall design: Control and heat stressed (35 °C for 24h at the time of meiosis) anthers of Mv 17-09 and Ellvis cultivars were subjected to RNA seq to reveal the transcriptional background of heat susceptibility of meiosis.