Project description:A biological phenomenon in which hybrids exhibit superior phenotypes from its parental inbred lines known as heterosis, has been widely exploited in plant breeding and extensively used in crop improvement. Hybrid rice has immense potential to increase yield over other rice varieties and hence is crucial in meeting increasing demand of rice globally. Moreover, the molecular basis of heterosis is still not fully understood and hence it becomes imperative to unravel its genetic and molecular basis. In this context, RNA sequencing technology (RNA-Seq) was employed to sequence transcriptomes of two rice hybrids, Ajay and Rajalaxmi, their parental lines, CRMS31A (sterile line, based on WA-CMS) and CRMS32A (sterile line based on Kalinga-CMS) respectively along with the common restorer line of both hybrids, IR-42266-29-3R at two critical rice developmental stages viz., panicle initiation (PI) and grain filling (GF). Identification of differentially expressed genes (DEGs) at PI and GF stages will further pave the way for understanding heterosis. In addition, such kind of study would help in better understanding of heterosis mechanism and genes up-regulated and down-regulated during the critical stages of rice development for higher yield.
Project description:Heterosis is an important biological phenomenon; however, the role of small RNA (sRNA) in heterosis of hybrid rice remains poorly described. Here, we performed sRNA profiling of F1 super-hybrid rice LYP9 and its parents using high-throughput sequencing technology, and identified 355 distinct mature microRNAs and trans-acting small interfering RNAs, 69 of which were differentially expressed sRNAs (DES) between the hybrid and the mid-parental value. Among these, 34 DES were predicted to target 176 transcripts, of which 112 encoded 94 transcription factors. Further analysis showed that 67.6% of DES expression levels were negatively correlated with their target mRNAs either in flag leaves or panicles. The target genes of DES were significantly enriched in some important biological processes, including the auxin signalling pathway, in which existed a regulatory network mediated by DES and their targets, closely associated with plant growth and development. Overall, 20.8% of DES and their target genes were significantly enriched in quantitative trait loci of small intervals related to important rice agronomic traits including growth vigour, grain yield, and plant architecture, suggesting that the interaction between sRNAs and their targets contributes to the heterotic phenotypes of hybrid rice. Our findings revealed that sRNAs might play important roles in hybrid vigour of super-hybrid rice by regulating their target genes, especially in controlling the auxin signalling pathway. The above finding provides a novel insight into the molecular mechanism of heterosis. We constructed six sRNA sequencing libraries and six mRNA sequencing libraries of flag leaves and panicles of the super-hybrid rice Liangyou-pei9 (LYP9) combination at the grain-filling stage. The above hybrid rice combination includes F1 hybrid LYP9 and its parental lines including the male-sterile line Peiai64s (PA64s) and the restorer line 93-11.
Project description:Gibberellins control a wide range of aspects of plant growth and development. Although a series of mutant of the signaling pathway has been identified, the global regulatory network underlying gibberellin signal transduction has not been revealed. To address this issue, we performed microarray analysis with rice gibberellin signaling mutants, gid1, gid2, slr, and the parental cultivar Taichung 65.
Project description:Iron toxicity is one of the most common mineral disorders affecting Oryza sativa production in flooded lowland fields. Efforts have been made to develop new rice varieties tolerant to Fe toxicity (+Fe). Oryza meridionalis is an endemic from Northern Australia and grows in regions with Fe rich soils, which may provide Fe tolerance genes and mechanisms that can be used for adaptive breeding. Aiming to understand tolerance mechanisms in rice, we screened a population of interspecific introgression lines (IL) from a cross between O. sativa and O. meridionalis for the identification of QTLs contributing to Fe excess tolerance. Six putative QTLs were identified. A line carrying one introgression from O. meridionalis on chromosome 9 associated with one QTL for leaf bronzing score was identified as tolerant in terms of lipid peroxidation and electrolyte leakage despite presenting very high shoot Fe concentrations. Further physiological, biochemical, ionomic and transcriptomic analyses showed that the IL tolerance could be partly explained by Fe partitioning between the leaf sheath and culm. After the in silico construction of an interspecific hybrid genome to map the sequences from transcriptomic analysis, we identified 47 and 27 genes from O. meridionalis up and down-regulated, respectively, by Fe treatment on the tolerant IL. Among possible genes associated with shoot-based tolerance, we identified metallothionein-like proteins, genes from glutathione S-transferase family and transporters from ABC and Major Facilitator Superfamily. This is the first work to demonstrate that introgressions of O. meridionalis in O. sativa genome confer increased tolerance to +Fe
Project description:Using a whole-genome oligonucleotide microarray designed based on known and predicted indica rice genes, we investigated transcriptome profiles in developing leaves and panicles of super hybrid rice LYP9 and its parental cultivar 93-11 and PA64s. We detected 22,266 expressed genes out of 36,926 total gene set collectively from seven tissues, including leaves at seedling and tillering stages, flag leaves at booting, heading, flowering, and filling stages, and panicle at filling stage. Clustering result showed that expression profiles between F1 and its parental lines were always more similar than that between the two parental lines. Out of the total gene set, 7,078 were shared by all sampled tissues and 3,926 (10.6%) were differentially-expressed genes (DG). As we divided DG into those between the parents (DGPP) and between the hybrid and its parents (DGHP), the comparative results showed that genes in the two categories, Energy metabolism and transport, were enriched in DGHP rather than in DGPP. The majority of genes were identified as additive expression, and non-additive expression only took a minority (0.53%-1.35%) of the total genes. In addition, we correlated the concurrence of DG and yield-related QTL, providing a potential group of genes as heterosis-related. We investigated transcriptome profiles in developing leaves and panicles of super hybrid rice LYP9 and its parental cultivar 93-11 and PA64s for seven tissues, and there are at least three independent replicates for each sample pair.
Project description:Here, we present OryzaPG-DB, a rice proteome database based on shotgun proteogenomics, which incorporates the genomic features of experimental shotgun proteomics data. This version of the database was created from the results of 27 nanoLC-MS/MS runs on a hybrid ion trap-orbitrap mass spectrometer, which offers high accuracy for analyzing tryptic digests from undifferentiated cultured rice cells. Peptides were identified by searching the product ion spectra against the protein, cDNA, transcript and genome databases from Michigan State University, and were mapped to the rice genome. Approximately 3200 genes were covered by these peptides and 40 of them contained novel genomic features. Users can search, download or navigate the database per chromosome, gene, protein, cDNA or transcript and download the updated annotations in standard GFF3 format, with visualization in PNG format. In addition, the database scheme of OryzaPG was designed to be generic and can be reused to host similar proteogenomic information for other species. OryzaPG is the first proteogenomics-based database of the rice proteome, providing peptide-based expression profiles, together with the corresponding genomic origin, including the annotation of novelty for each peptide.
Project description:Based our serial analysis of gene expression (SAGE) data from an elite Chinese super-hybrid rice (LYP9) and its parental cultivars (93-11 and PA64s) in three major tissue types at three different developmental stages, we obtained a much more comprehensive view of genes that related to rice heterosis and analyzed the potential effects of gene-expression difference on the heterosis of rice.These heterotic expression genes among different genotypes provided new avenues for exploring the molecular mechanisms underlying heterosis, including variable gene expression patterns. Keywords: Heterosis study by SAGE We constructed nine SAGE libraries parallelly, including root at the first tillering stage, leaf at the milky stage of rice grain maturation, and panicle at the pollen-maturing stage of hybrid rice (LYP9) and its paternal lines (9311, PA64s).