Characterisation of Indica Special Protein (ISP), a marker protein for the differentiation of Oryza sativa subspecies indica and japonica.
ABSTRACT: Based on both morphological and physiological traits, Asian cultivated rice (Oryza sativa L.) can be classified into two distinct subspecies, indica and japonica. To better understand the differences between the two subspecies, a proteomic approach was used to profile proteins present in the yellow seedling stage of 10 indica and 10 japonica rice varieties. We report the discovery of a new protein, Indica Special Protein (ISP), which was only detected in yellow seedlings of indica varieties, and was absent from japonica varieties. Hence, ISP may represent a key gene for the differentiation of indica and japonica subspecies.
Project description:Indica and japonica are two main subspecies of Asian cultivated rice (Oryza sativa L.) that differ clearly in morphological and agronomic traits, in physiological and biochemical characteristics and in their genomic structure. However, the proteins and genes responsible for these differences remain poorly characterized. In this study, proteomic tools, including two-dimensional electrophoresis and mass spectrometry, were used to globally identify proteins that differed between two sequenced rice varieties (93-11 and Nipponbare). In all, 47 proteins that differed significantly between 93-11 and Nipponbare were identified using mass spectrometry and database searches. Interestingly, seven proteins were expressed only in Nipponbare and one protein was expressed specifically in 93-11; these differences were confirmed by quantitative real-time PCR and proteomic analysis of other indica and japonica rice varieties. This is the first report to successfully demonstrate differences in the protein composition of indica and japonica rice varieties and to identify candidate proteins and genes for future investigation of their roles in the differentiation of indica and japonica rice.
Project description:Japonica and indica are two important subspecies in cultivated Asian rice. Irradiation is a classical approach to induce mutations and create novel germplasm. However, little is known about the differential response between japonica and indica rice after γ radiation. Here, we utilized the RNA sequencing and Weighted Gene Co-expression Network Analysis (WGCNA) to compare the transcriptome differences between japonica Nipponbare (NPB) and indica Yangdao6 (YD6) in response to irradiation. Japonica subspecies are more sensitive to irradiation than the indica subspecies. Indica showed a higher seedling survival rate than japonica. Irradiation caused more extensive DNA damage in shoots than in roots, and the severity was higher in NPB than in YD6. GO and KEGG pathway analyses indicate that the core genes related to DNA repair and replication and cell proliferation are similarly regulated between the varieties, however the universal stress responsive genes show contrasting differential response patterns in japonica and indica. WGCNA identifies 37 co-expressing gene modules and ten candidate hub genes for each module. This provides novel evidence indicating that certain peripheral pathways may dominate the molecular networks in irradiation survival and suggests more potential target genes in breeding for universal stress tolerance in rice.
Project description:Potential environmental risks of genetically modified (GM) crops have raised concerns. To better understand the effect of transgenic rice on the bacterial community in paddy soil, a field experiment was carried out using pairs of rice varieties from two subspecies (indica and japonica) containing bar transgene with herbicide resistance and their parental conventional rice. The 16S rRNA gene of soil genomic DNA from different soil layers at the maturity stage was sequenced using high-throughput sequencing on the Illumina MiSeq platform to explore the microbial community diversity among different rice soils. There were no significant differences in diversity indices between transgenic japonica rice and its sister conventional rice (japonica pair) among different soil layers, but, significant differences was observed between transgenic indica rice and its conventional rice (indica pair) in the topsoil layer around concentrated rice roots according to the ace diversity index. Though the japonica rice soil and indica rice soil were shared several key genera, including Rivibacter, Anaeromyxobacter, Roseomonas, Geobacter, Thiobacillus, Clostridium, and Desulfobulbus, the primary bacterial genera in indica rice soil were different from those in japonica rice. Synechococcus and Dechloromonas were present in japonica rice samples, while Chloronema, Flexibacter, and Blastocatella were observed in indica rice soil. Moreover, the abundance of genera between GM and non-GM varieties in japonica rice was significantly different from indica rice, and several bacterial communities influenced these differences. Anaerovorax was more abundant in transgenic japonica rice soil than conventional rice soil, while it was deficient in transgenic indica rice soil compared to conventional rice soil, and opposite responses to Deferrisoma were in that of indica rice. Thus, we concluded that transgenic indica and japonica rice had different effects on soil bacteria compared with their corresponding sister conventional rice. However, these composition and abundance difference only occurred for a few genera but had no effect on the primary genera and soil characteristics were mainly contributed to these differences. Thus, differences in bacterial community structure can be ignored when evaluating the impacts of transgenic rice in the complex soil microenvironment.
Project description:Somatic embryogenesis is a unique process in plants and has considerable interest for biotechnological application. Compare to japonica, indica rice has been less responsive to in vitro culture. We used Illumina Hiseq 2000 sequencing platform for comparative transcriptome analysis between two rice subspecies at six different developmental stages combined with a tag-based digital gene expression profiling. Global gene expression among different samples showed greater complexity in japonica rice compared to indica which may be due to polyphyletic origin of two rice subspecies. Expression pattern in initial stage indicate major differences in proembryogenic callus induction phase that may serve as key regulator to observe differences between both subspecies. Our data suggests that phytohormone signaling pathways consist of elaborate networks with frequent crosstalk, thereby allowing plants to regulate somatic embryogenesis pathway. However, this crosstalk varies between the two rice subspecies. Down regulation of positive regulators of meristem development (i.e. KNOX, OsARF5) and up regulation of its counterparts (OsRRs, MYB, GA20ox1/GA3ox2) in japonica may be responsible for its better regeneration and differentiation of somatic embryos. Comprehensive gene expression information in the present experiment may also facilitate to understand the monocot specific meristem regulation for dedifferentiation of somatic cell to embryogenic cells.
Project description:Hybrid sterility is a major form of postzygotic reproductive isolation. Although reproductive isolation has been a key issue in evolutionary biology for many decades in a wide range of organisms, only very recently a few genes for reproductive isolation were identified. The Asian cultivated rice (Oryza sativa L.) is divided into two subspecies, indica and japonica. Hybrids between indica and japonica varieties are usually highly sterile. A special group of rice germplasm, referred to as wide-compatibility varieties, is able to produce highly fertile hybrids when crossed to both indica and japonica. In this study, we cloned S5, a major locus for indica-japonica hybrid sterility and wide compatibility, using a map-based cloning approach. We show that S5 encodes an aspartic protease conditioning embryo-sac fertility. The indica (S5-i) and japonica (S5-j) alleles differ by two nucleotides. The wide compatibility gene (S5-n) has a large deletion in the N terminus of the predicted S5 protein, causing subcellular mislocalization of the protein, and thus is presumably nonfunctional. This triallelic system has a profound implication in the evolution and artificial breeding of cultivated rice. Genetic differentiation between indica and japonica would have been enforced because of the reproductive barrier caused by S5-i and S5-j, and species coherence would have been maintained by gene flow enabled by the wide compatibility gene.
Project description:Understanding how fungi specialize on their plant host is crucial for developing sustainable disease control. A traditional, centuries-old rice agro-system of the Yuanyang terraces was used as a model to show that virulence effectors of the rice blast fungus Magnaporthe oryzaeh play a key role in its specialization on locally grown indica or japonica local rice subspecies. Our results have indicated that major differences in several components of basal immunity and effector-triggered immunity of the japonica and indica rice varieties are associated with specialization of M. oryzae. These differences thus play a key role in determining M. oryzae host specificity and may limit the spread of the pathogen within the Yuanyang agro-system. Specifically, the AVR-Pia effector has been identified as a possible determinant of the specialization of M. oryzae to local japonica rice.
Project description:China is the first country to use heterosis successfully for commercial rice production. This study compared the main quality characteristics (head rice rate, chalky rice rate, chalkiness degree, gel consistency, amylose content, and length-to-width ratio) of 635 rice varieties (not including upland and glutinous rice) released from 2000 to 2014 to establish the quality status and offer suggestions for future rice breeding for grain quality in China. In the past 15 years, grain quality in japonica rice and indica hybrid rice has improved. In japonica rice, inbred varieties have increased head rice rates and decreased chalkiness degree over time, while hybrid rice varieties have decreased chalky rice rates and chalkiness degree. In indica hybrid rice, the chalkiness degree and amylose contents have decreased and gel consistency has increased. Improvements in grain quality in indica inbred rice have been limited, with some increases in head rice rate and decreases in chalky rice rate and amylose content. From 2010 to 2014, the percentage of indica varieties meeting the Grade III national standard of rice quality for different quality traits was low, especially for chalky rice rate and chalkiness degree. Japonica varieties have more superior grain quality than indica rice in terms of higher head rice rates and gel consistency, lower chalky rice rates and chalkiness degree, and lower amylose contents, which may explain why the Chinese prefer japonica rice. The japonica rice varieties, both hybrid and inbred, had similar grain qualities, but this varied in indica rice with the hybrid varieties having higher grain quality than inbred varieties due to significantly better head rice rates and lower chalkiness degree. For better quality rice in future, the chalky rice rate and chalkiness degree should be improved in japonica rice along with most of the quality traits in indica rice.
Project description:To understand the genetic diversity and indica-japonica differentiation in Bangladesh rice varieties, a total of 151 accessions of rice varieties mostly Bangladesh traditional varieties including Aus, Boro, broadcast Aman, transplant Aman and Rayada varietal groups were genotyped using 47 rice nuclear SSRs. As a result, three distinct groups were detected by cluster analysis, corresponding to indica, Aus and japonica rice. Among deepwater rice varieties analyzed some having particular morphological features that mainly corresponded to the japonica varietal group. Some small seeded and aromatic varieties from Bangladesh also corresponded to the japonica varietal group. This research for the first time establishes that the japonica varietal group is a prominent component of traditional varieties in Bangladesh, particularly in deepwater areas.
Project description:Aluminum (Al) at high concentrations inhibits root growth, damage root systems, and causes significant reductions in rice yields. Indica and Japonica rice have been cultivated in distinctly different ecological environments with different soil acidity levels; thus, they might have different mechanisms of Al-tolerance. In the present study, transcriptomic analysis in the root apex for Al-tolerance in the seedling stage was carried out within Al-tolerant and -sensitive varieties belonging to different subpopulations (i.e., Indica, Japonica, and mixed). We found that there were significant differences between the gene expression patterns of Indica Al-tolerant and Japonica Al-tolerant varieties, while the gene expression patterns of the Al-tolerant varieties in the mixed subgroup, which was inclined to Japonica, were similar to the Al-tolerant varieties in Japonica. Moreover, after further GO (gene ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) analyses of the transcriptomic data, we found that eight pathways, i.e., "Terpenoid backbone biosynthesis", "Ribosome", "Amino sugar and nucleotide sugar metabolism", "Plant hormone signal transduction", "TCA cycle", "Synthesis and degradation of ketone bodies", and "Butanoate metabolism" were found uniquely for Indica Al-tolerant varieties, while only one pathway (i.e., "Sulfur metabolism") was found uniquely for Japonica Al-tolerant varieties. For Al-sensitive varieties, one identical pathway was found, both in Indica and Japonica. Three pathways were found uniquely in "Starch and sucrose metabolism", "Metabolic pathway", and "Amino sugar and nucleotide sugar metabolism".
Project description:<h4>Background</h4>Cultivated rice consists of two subspecies, Indica and Japonica, that exhibit well-characterized differences at the morphological and genetic levels. However, the differences between these subspecies at the transcriptome level remains largely unexamined. Here, we provide a comprehensive characterization of transcriptome divergence and cis-regulatory variation within rice using transcriptome data from 91 accessions from a rice diversity panel (RDP1).<h4>Results</h4>The transcriptomes of the two subspecies of rice are highly divergent. Japonica have significantly lower expression and genetic diversity relative to Indica, which is likely a consequence of a population bottleneck during Japonica domestication. We leveraged high-density genotypic data and transcript levels to identify cis-regulatory variants that may explain the genetic divergence between the subspecies. We identified significantly more eQTL that were specific to the Indica subspecies compared to Japonica, suggesting that the observed differences in expression and genetic variability also extends to cis-regulatory variation.<h4>Conclusions</h4>Using RNA sequencing data for 91diverse rice accessions and high-density genotypic data, we show that the two species are highly divergent with respect to gene expression levels, as well as the genetic regulation of expression. The data generated by this study provide, to date, the largest collection of genome-wide transcriptional levels for rice, and provides a community resource to accelerate functional genomic studies in rice.