Project description:The lack of MIRNA set and genome sequence of O. rufipogon (the ancestor of the cultivated rice) has limited to answer the role of MIRNA genes in rice domestication. In this study, a genome, three small RNA populations and a degradome of O.rufipogon were sequenced by Illumina platform and miRNA expression were investigated by miRNA chips. A de novo genome was assembled using ~55x coverage of raw sequencing data and a total of 387 MIRNAs were identified in the O. rufipogon genome based on ~5.2 million unique small RNA reads from three different tissues of O. rufipogon. Of these O. rufipogon MIRNAs, 259 were not found in the cultivated rice, suggesting loss of these MIRNAs in the cultivated rice. We also found that 48 MIRNAs were novel in the cultivated rice, suggesting that they were potential targets of domestication selection. Some miRNAs showed significant expression difference in the wild and cultivated rice, suggesting that expression of miRNA could also be a target of domestication, as demonstrated for the miR164 family. Our results illustrated MIRNA genes, like protein-coding genes, were significantly shaped during rice domestication and could be one of the driven forces contributed to rice domestication.
Project description:Rice has developed several morphological and physiological strategies to adapt to phosphate starvation stress. In order to elucidate the molecular bases of response due to phosphate stress particularly the transcriptional profile of genotypes with variation in tolerance to phosphate starvation, we analyzed the gene expression profiles of 3 japonica rice cultivars and an indica cultivar with different levels of tolerance to phosphate starvation using the RNA-Seq method. We constructed a total of 48 libraries corresponding to root and shoot of the 4 cultivars for control (0 d) and âP treatment (22 d) with three biological replicates for root and shoot samples in each cultivar. Approximately 254 million sequenced tags were mapped onto the reference rice genome sequence (IRGSP1.0) and an average of about 5,000 transcripts in each genotype were found to be responsive to Pi-starvation. Comparative analysis of the responsive transcripts revealed an overall similarity in the transcriptome signatures resulting from phosphate starvation as well as distinct differences that distinguish the degree of tolerance among the 4 cultivars. We elucidated a set of core responsive transcripts commonly expressed in both root and shoot with different levels of expression reflecting variation as well genotype specificity in tolerance to Pi-starvation. De novo assembly of unmapped reads generated a large set of sequence assemblies that represent potential new transcripts that may be involved in tolerance to phosphate deficiency. Characterization of 88 assemblies unaligned in the reference genome revealed several dozen transcripts which correspond to plant ESTs. This study provides an overview of the diversity in response to P-starvation stress that can be used to identify the major genes for improving Pi acquisition and utilization in rice and other cereal crops. Note: Samples in DRA were assigned the same sample accession. This is incorrect as there are different samples, hence âSource Nameâ was replaced with new values. Comment[ENA_SAMPLE] contains the original DRA sample accessions.