Transcriptome profiling provide new insights into the molecular mechanism of grapevine response to heat, drought, and combined stress

Grapes are a globally important fruit and usually grown in arid- and semi-arid areas. Investigating the molecular mechanism of drought and heat tolerance will provide important information for the improvement of grapevine response to drought and heat stresses. In the present study, one-year-old 'Cabernet Sauvignon' cuttings were subjected to drought (D), heat (H), and a combination of the two (HD), and RNA-seq was conducted using the Illumina Hiseq 4000 platform; 47.67-66.80 million clean reads were generated. In total, 2958, 1286, and 5057 differentially expressed genes (DEGs) were detected in the H, D, and HD groups, respectively. Based on the GO database, DEGs were annotated to 2732 (H), 2008 (D), and 3281 (HD) functional groups. A total of 733 (D), 1129 (H), and 1954 (HD) DEGs were annotated to 97, 107, and 121 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, respectively. Photosynthesis-related and hormone signal pathways were significantly regulated in these stresses. Many transcription factors (TFs), including MYBs, NACs, HSFs, and bHLH, played an important role in heat and drought grapevine stress. Notably, a total of 19 (H), 4 (D), and 36 (HD) DEGs were enriched in the spliceosome (vvi03040) pathway, suggesting that alternative splicing (AS) plays a key post-transcriptional regulatory role in response to the single and combination stressors. This study not only clarifies the mechanism underlying grapevine responses to heat and drought stress, but it also provides the candidate genes involved with these stressors.