Figure 5.

Differential gene expression analysis and data validation of mature pollen transiently heat stressed at the tetrad stage. A, Differential gene expression (the base 2 logarithm fold change) in mature maize pollen samples from plants exposed to heat stress relative to control (nonstressed) is plotted versus average gene expression level (i.e. logarithm of mean counts normalized for difference in library sizes). Red color indicates differentially expressed genes (DEG) exhibiting significant expression. B, RT-qPCR analysis shows that expression of HSP genes is still increased in mature pollen 2 weeks after application of heat stress at the tetrad stage. The asterisk indicates significant difference at P < 0.001; one-tailed t test comparing heat-stressed samples to nonstressed samples. n = 3 biological replicates, each with 3 technical replicates. C, Analysis of interactions of differentially expressed genes in response to heat stress. Well-known HSP markers for heat-stress responses are highlighted in yellow. A threshold of 0.7 of edge confidence was used. Thicker and thinner lines represent edge confidence of 0.9 and 0.7, respectively. A detailed list of the genes included in the gene interaction analysis can be found in Supplemental Table S4A. D, A number of genes encoding kinases, including RLKs, are differentially expressed in mature pollen after application of heat stress at the tetrad stage.