Project description:We report the application of RNA-seq technology for highthroughput profiling of photosynthetic and non-photosynthetic seeds of Arabidopsis chlorophyll synthase mutant seeds. By generating over 21 GB of sequence data from these seeds, we showed that genes involved in oil accumulation in non-photosynthetic seeds were significantly induced compared to photosynthtic seeds. Additionally we found that genes involved in the plastidal oxidative pentos phosphate pathway were significantly upregulated in the non-photosynthetic seed opposite to photosynthetic seeds. Overall our RNA-seq analysis revealled the genes and pathway interaction underpinining oil accumulation in non-photosynthetic seeds.
Project description:Arabidopsis seeds expressing the castor fatty acid hydroxylase accumulate hydroxylated fatty acids up to 17% of total fatty acids in seed triacylglycerols, however total seed oil is also reduced up to 50%. Investigations into the cause of the reduced oil phenotype through in vivo [14C]acteate and [3H]2O metabolic labeling of developing seeds surprisingly revealed that the rate of de novo fatty acid synthesis within the transgenic seeds was approximately half that of control seeds. Addition of castor phospholipid:diacylglycerol acyltransferase (PDAT) increased hydroxylated fatty acid content of the seed oil, increased the rate of fatty acid synthesis, and mostly restored seed oil levels. RNAseq analysis indicated no changes in expression of fatty acid synthesis genes in hydroxylase-expressing plants.
Project description:Environmental stresses such as drought, salinity and both high and low temperature are frequently faced by crops all over the world and can be considered major limiting factors for plant geographical distribution and productivity. Breeding has allowed creation of crops more adapted to some of the adverse environmental conditions and to overcome the geographical limitation without major consequences to productivity. However, due to the climate changes observed in the last few decades, some agricultural areas have experienced the “green seed problem” characterized by chlorophyll retention in mature seeds. This is problematic in oil seed crops such as soybean and canola since it is related to lower seed and oil quality, resulting in serious financial losses. Besides the environmental factors, there are also genetic components controlling the susceptibility of different cultivars to green seed production. Understanding the molecular mechanisms controlling chlorophyll retention in seeds is crucial to allow advanced molecular breeding techniques and genetic engineering as a way to increase tolerance to this growing problem. We have used maturing soybean seeds of the cultivar MG/BR 46, harvested in R6, R7 and R8, produced under non-stressed and stressed environmental conditions, to understand he molecular basis of chlorophyll degradation and, consequently, its retention during soybean seed maturation.
Project description:Sesame seeds is an important traditional crop with high oil content and other abundant nutrients which are very beneficial for diet and health of human being. However, the molecular mechanism for metabolite accumulation, especially for oil and phenylpropanoid biosynthesis, is still not very clear in sesame. In this study, the transcriptome profiles of black and white sesame seeds were compared by RNA-sequencing. Transcriptome analysis showed that the expression patterns of genes encoding phenylpropanoid pathway enzymes were different between the two sesame cultivars. Compared with white sesame, most of genes involved in oil biosynthesis were significantly down-regulated in black sesame.
Project description:Environmental stresses such as drought, salinity and both high and low temperature are frequently faced by crops all over the world and can be considered major limiting factors for plant geographical distribution and productivity. Breeding has allowed creation of crops more adapted to some of the adverse environmental conditions and to overcome the geographical limitation without major consequences to productivity. However, due to the climate changes observed in the last few decades, some agricultural areas have experienced the âgreen seed problemâ characterized by chlorophyll retention in mature seeds. This is problematic in oil seed crops such as soybean and canola since it is related to lower seed and oil quality, resulting in serious financial losses. Besides the environmental factors, there are also genetic components controlling the susceptibility of different cultivars to green seed production. Understanding the molecular mechanisms controlling chlorophyll retention in seeds is crucial to allow advanced molecular breeding techniques and genetic engineering as a way to increase tolerance to this growing problem. We have used maturing soybean seeds of the cultivar MG/BR 46, harvested in R6, R7 and R8, produced under non-stressed and stressed environmental conditions, to understand he molecular basis of chlorophyll degradation and, consequently, its retention during soybean seed maturation. Soybean seeds were produced under stressed and non-stressed conditions and harvested in 3 different stages of maturation: R6 non-stressed, R7 non-stressed, R8 non-stressed, R6 stressed, R7 stressed, R8 stressed.
Project description:Understanding the regulation of lipid metabolism is vital for genetic engineering of Brassica napus (B. napus) to increase oil yield or modify oil composition. We report the application of Illumina Hiseq 2000 for transcriptome profiling of seeds of B. napus at different developmental stages, which may uncover the dynamic changes in lipid metabolism and reveal key genes involved in lipid biosynthesis and degradation. Total RNA from developing seeds at 2, 4, 6, and 8 weeks after pollination (WAP) were isolated and sequenced separately. The gene expression levels of all samples were quantified and normalized by the DESeq normalization. We found that the biosynthesis of fatty acids is a dominant cellular process from 2 to 6 WAP, while the degradation mainly happens after 6 WAP. Two genes, encoding for acetyl-CoA carboxylase and acyl-ACP desaturase, might be critical for fatty acid biosynthesis in oil rape seeds. This study provides insight into the mechanism underlying lipid metabolism and reveals candidate genes that are worthy of further investigation for their values in genetic engineering of B. napus.
Project description:Arabidopsis seeds expressing the castor fatty acid hydroxylase accumulate hydroxylated fatty acids up to 17% of total fatty acids in seed triacylglycerols, however total seed oil is also reduced up to 50%. Investigations into the cause of the reduced oil phenotype through in vivo [14C]acteate and [3H]2O metabolic labeling of developing seeds surprisingly revealed that the rate of de novo fatty acid synthesis within the transgenic seeds was approximately half that of control seeds. Addition of castor phospholipid:diacylglycerol acyltransferase (PDAT) increased hydroxylated fatty acid content of the seed oil, increased the rate of fatty acid synthesis, and mostly restored seed oil levels. RNAseq analysis indicated no changes in expression of fatty acid synthesis genes in hydroxylase-expressing plants. Transcript profiles of Arabidopsis developing seeds of three lines, at three stages of development were generated by deep sequencing, in triplicate, using Illumina.
Project description:Two Euphorbiaceae oil trees, Vernicia and Jatropha, were chosen to make a comparative transcriptomic study, with a focus on the differential oil accumulation process. Transcriptome sequencing was conducted with seeds at the initial- and fast- stage of oil accumulation from both.
Project description:Tung oil, the major product of tung tree (Vernicia fordii) seeds, is one of the highest quality oils for industrial applications and has been considered to the production of biodiesel. Because of the poor agronomical traits of this crop, efforts have been made to breed tung tree for higher fruit yield and for modification of oil properties to be used as biodiesel, or to engineer higher yielding plants to produce tung oil. However, these efforts have been hampered by the lack of molecular information since there is no available genome and the identified and characterized transcripts of tung are scarce. Furthermore, there are still many knowledge gaps regarding tung oil biosynthesis. To provide a comprehensive and accurate foundation for molecular studies of tung tree, herein we present the reference transcriptome dataset of tung mature seeds. A set of 43,081,927 ESTs were assembled into 47,585 unigenes. The homology search using blastx against the GenBank non-redundant protein database and the Swiss-Prot database resulted in the annotation of 96 % and 81% of the unigenes, respectively. We also systematically arranged the series of transcripts potentially associated with oil biosynthesis and breakdown and examined the expression profile of a subset of those genes in samples from different stages of seed development, providing a valuable source of genes and transcriptional information related to these pathways. This study represents the first large-scale transcriptome annotation of tung tree seeds and will be useful to breed tung for oil properties and other agronomical traits.
Project description:Genetic/genome diversity underlying variation in seed oil composition and content among soybean varieties is largely attributed to differences in transcript sequences and/or transcript accumulation of oil production related genes in seeds. Discovery and analysis of sequence and expression variations in these genes will accelerate soybean oil quality improvement. In an effort to identify these variations, we sequenced the transcriptomes of soybean seeds from nine lines varying in oil composition and/or total oil content. Our results showed that 69,338 distinct transcripts from 32,885 annotated genes were expressed in seeds. A total of 8,037 transcript expression polymorphisms and 50,485 transcript sequence polymorphisms (48,792 SNPs and 1,693 small Indels) were identified among the lines. Effects of the transcript polymorphisms on their encoded protein sequences and functions were predicted. The studies also provided independent evidence that the lack of FAD2-1A gene activity and a non-synonymous SNP in the coding sequence of FAB2C caused elevated oleic acid and stearic acid levels in soybean lines M23 and FAM94-41, respectively. As a proof-of-concept, we developed an integrated RNA-seq and bioinformatics approach to identify and functionally annotate transcript polymorphisms, and demonstrated its high effectiveness for discovery of genetic and transcript variations that result in altered oil quality traits. The collection of transcript polymorphisms coupled with their predicted functional effects will be a valuable asset for further discovery of genes, gene variants, and functional markers to improve soybean oil quality.