Genome-wide comparative transcriptome profiling of two contrasting chilling tolerant rice genotypes in response to early chilling stress

To understand the molecular mechanisms underlying chilling tolerance in rice, transcriptomic deep sequencing was performed to reveal the differentially expressed genes between chilling tolerance chromosome substitution line (CSL), DC90 and its chilling-sensitive recurrent parent 9311 under early chilling stress events. Our results revealed a set of DEGs with higher basal expression in DC90 by comparison with 9311. They were functionally enriched in GO terms, such as, response to stress, response to stimulus, and response to abiotic stimulus, suggesting their positive role in intrinsic chilling tolerance. Common up-regulated and down-regulated DEGs were enriched in 26 and 34 GO terms, including response to stimulus, response to stress, and response to abiotic stimulus, respectively. Furthermore, comparative transcriptomic analysis between DC90 and 9311 in response to early chilling stress revealed 502 DEGs specifically identified in DC90. Most of gene loci were located beyond introgressed regions, implying that the introgression led to reprogramming of transcriptome in response to early chilling stress. CARMO platform analysis of these DEGs presented a complex regulatory network, including phytohormone signaling, photosynthesis pathway, that coordinately involved in chilling tolerance response of DC90. Here, the unveiled molecular regulatory network shed light on deep understanding the mechanisms of rice chilling tolerance. As well, chilling tolerant-QTLs and co-localized DEGs in introgressed fragments, will be focused for further functional investigation of the molecular mechanisms of early chilling stress response in rice. Overall design: Transcriptomic profiling of DC90 and 9311 (YD6) were performed by RNA sequencing using Illumina Hiseq platform

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