Gene expression profiling of Rhododendron pulchrum leaves under drought stress

Droughts, due to global warming, have become a major abiotic stress for plants. Rhododendron pulchrum is among the top 10 most sought-after flowers in China; however, because of its sensitivity to water, it is often drought-stressed in landscaping practices. This has restricted its promotion in garden landscaping. Thus, we performed transcriptomic analyses of this species under moderate to severe dehydration and rehydration to investigate the dynamics of gene expression. A total of 310, 1452, and 2610 differentially expressed genes (DEGs) were identified under moderate drought stress vs control, moderate drought vs severe drought, and severe drought vs re-watering conditions, respectively. A total of 209 transcription factors (TFs) were shown to be dehydration-responsive. Trend analysis of all the DEGs yielded 26 profiles of dynamic expression patterns. Among them, 6 profiles could be further grouped into cluster 1 (1230 DEGs) and cluster 2 (1164 DEGs) representing drought-induced and drought-repressed conditions, respectively. Transcriptomic changes in the key GO/pathways in this plant were analyzed and have been discussed in relation to hormone signal transduction, metabolic processes, and protein protective activity during drought treatment. This study provides valuable dataset regarding R. pulchrum gene expression changes in response to drought and may facilitate identification of potential genes that could be used to improve drought tolerance via genetic engineering of non-model plant species.