Heat Tolerance of Maize - Improving the Tolerance By Next Generation Plant Science

Due to climate change, the number and intensity of heat waves in Central Europe is expected to increase. This in turn will affect maize cultivation. Especially anther fertility and the coordination of male and female flowering are disturbed by heat stress. Further, young seedlings can be impaired when maize is sown as a biomass crop after cereals in a hot summer period. Our project aims to identify candidate genes for heat tolerance and understand the basic mechanisms of response to heat stress in maize by transcriptome profiling.

Eight European Flint and Dent inbred lines were compared concerning their reaction upon heat stress. Phenotyping was performed in growth chambers at three heat levels (25°C, 32°C and 38°C) during seedling stage. A phenotypic heat tolerance index was defined as change of six growth traits over heat levels. Transcriptomic variation was revealed by RNA sequencing with a total of about 1.5 billion sequence reads. After aligning to a reference sequence, the data was subjected to differential expression analysis. A linear model served to identify 607 differentially expressed genes with increasing stress intensity. To find genes playing an important role for heat tolerance, a second linear model was used where change of gene expression with increasing heat stress correlated with phenotypic heat tolerance of the inbred lines. By means of this 23 candidate genes were selected.

To get further tools for practical breeding, molecular markers for heat tolerance will be identified by QTL mapping with segregating populations derived from aforementioned inbred lines.