Mining for heat-stress responsive genes by large scale gene expression data from Betula luminifera

Abstract

Global average temperature has been predicted to rise by 1.8–4.0 °C within this century, accompanied by an increase in the magnitude and frequency of high-temperature events. Developing new cultivars better adapted to high temperature is essential for forestry ecosystems. Analyzing smooth-bark birch (Betula luminifera) gene expression profiles in response to heat stress is critical to understanding how birch manages heat stress, and provides vital information to improve thermoresistance for stable wood production. In this study, the leaf transcriptomics of B. luminifera were evaluated, thus up- and down-regulated genes were identified under heat stress through digital gene expression analysis. Expression patterns of 17 related genes of two genotypes following exposure to heat stress were compared. A total of 867 differentially expressed genes were identified, including 447 upregulated genes and 420 downregulated genes under heat stress, while 10 genes and 58 genes were detected only in control and heat-stress leaves, respectively. Among them, Hsfs, HSPs, DREB2, Cpn60-β2, ATP9 and other genes involved in the response to heat stress displayed quantitative differences in expression between the genotypes. The expression levels of the transcription factors MybC2-L1 and MYC1 were repressed significantly under heat stress. These results showed that a panoply of genes were induced by heat stress, while the expression of many genes were reduced or off in the presence of excessively high temperatures. It can be speculated that the distinct expression levels between genotypes in response to heat stress underlie their different capacities to resist high temperatures.