Genome-wide investigation on transcriptional responses to drought stress in wild and cultivated rice

Whole transcriptomic sequencing of the drought-tolerant (DT) and drought-sensitive (DS) accessions of cultivated and wild rice under drought treatments was performed to uncover the mechanism of plant adaptation to drought and to facilitate the development of drought-tolerant cultivars in crops. By analyzing the differentially expressed genes (DEGs) between the drought-treated and untreated samples and their co-expressed pattern, we revealed distinct susceptibilities of different samples to the stress treatments and identified some specific transcription factors (TFs) and genes that play critical roles in rice adaptation to drought. Some drought-responsive genes or pathways unique to the wild rice were also detected, highlighting the importance of wild rice resources in developing elite cultivars. Furthermore, we showed that the DEGs in the DT accessions were enriched in the genome as clusters or hotspots in which previously identified drought-associated quantitative trait loci (QTLs) were overrepresented. The finding that a single hotspot contained up to 52 QTLs and involved as many as 20 traits implicates the complicated genetic architecture underlying the DT traits. These results provide new insights into the understanding of plant adaptation to drought and help effective manipulation of specific genes or gene cluster in crop breeding.