Project description:The prolamin-box binding factor-1 (pbf1) gene encodes a transcription factor that controls the expression of seed storage protein (zein) genes in maize. Prior studies show that pbf1 underwent selection during maize domestication, although how it affected trait change during domestication is unknown. To assay how pbf1 affects phenotypic differences between maize and teosinte, we compared isogenic lines (NILs) that differ for a maize vs.and teosinte alleles of pbf1. Kernel weight for the teosinte NIL (162 mg) is slightly and significantly greater than that for the maize NIL (156 mg). RNAseq data for developing kernels show that the teosinte allele of pbf1 is expressed at about twice the level of the maize allele. However, RNA and protein assays showed no difference in zein profiles between the two NILs. The lower expression for the maize pbf1 allele suggests that selection may have favored this change, however, how reduced pbf1 expression alters phenotype remains unknown. One possibility is that pbf1 regulates genes other than zeins and thereby a domestication trait. The observed drop in seed weight associated with the maize allele of pbf1 is counterintuitive, but could represent a negative pleiotropic effect of selection on some other aspect of kernel composition.
Project description:Maize kernel is an important source of food, feed and industrial raw materials. The illustration of the molecular mechanisms of maize kernel development will be helpful for the manipulation of maize improvements. Although a great many researches based on molecular biology and gecetics have greatly increased our understanding on the kernel development, many of the mechanisms controlling this important process remain elusive. In current study, a microarray with approximately 58,000 probes was used to study the dynamic gene expression during kernel development from the fertilization to physiological maturity. Samples from two consecutive time-points were paired and labeled using different fluorescent dyes (Cy3 and Cy5) and hybridized in the same array. Hybridization of slides was performed according to the manufacturer’s instructions (http://www.maizearray.org/). The hybridized slides were scanned by a Genepix 4000B (Axon, USA). A loop design was applied for running the microarray. Two replicates of each pair of samples were carried out to test both the reproducibility and quality of the chip hybridizations. By comparing six consecutive time-points, namely 1, 5, 10, 15, 25 and 35 days after pollination (DAP), 3,445 differentially expressed genes were identified. These genes were then grouped into 10 clusters showing specific expression patterns using a K-means clustering algorithm. An investigation of function and expression patterns of genes expanded our understanding of the regulation mechanism underlying the important developmental processes, cell division and kernel filling. The differential expression of genes involved in plant hormone signaling pathways suggested that phytohormone might play a critical role in the kernel developmental process. Moreover, regulation of some transcription factors and protein kinases might be involved in the whole developmental process. Keywords: Time course, development
Project description:Maize kernel is an important source of food, feed and industrial raw materials. The illustration of the molecular mechanisms of maize kernel development will be helpful for the manipulation of maize improvements. Although a great many researches based on molecular biology and gecetics have greatly increased our understanding on the kernel development, many of the mechanisms controlling this important process remain elusive. In current study, a microarray with approximately 58,000 probes was used to study the dynamic gene expression during kernel development from the fertilization to physiological maturity. Samples from two consecutive time-points were paired and labeled using different fluorescent dyes (Cy3 and Cy5) and hybridized in the same array. Hybridization of slides was performed according to the manufacturer’s instructions (http://www.maizearray.org/). The hybridized slides were scanned by a Genepix 4000B (Axon, USA). A loop design was applied for running the microarray. Two replicates of each pair of samples were carried out to test both the reproducibility and quality of the chip hybridizations. By comparing six consecutive time-points, namely 1, 5, 10, 15, 25 and 35 days after pollination (DAP), 3,445 differentially expressed genes were identified. These genes were then grouped into 10 clusters showing specific expression patterns using a K-means clustering algorithm. An investigation of function and expression patterns of genes expanded our understanding of the regulation mechanism underlying the important developmental processes, cell division and kernel filling. The differential expression of genes involved in plant hormone signaling pathways suggested that phytohormone might play a critical role in the kernel developmental process. Moreover, regulation of some transcription factors and protein kinases might be involved in the whole developmental process. To obtain the global gene expression profile during maize kernel development, a microarray with approximately 58,000 probes was used. The maize inbred line X178 was planted on the field. Each plant was self-pollinated by hand. The ears were harvested from healthy plants at 1, 5, 10, 15, 25 and 35 days after pollination (DAP), respectively. In order to increase the consistency & uniformity of the isolated kernels, the upper half and about one sixth of ears from the bottom were cut and discarded, the kernels were isolated from the rest part of the ears. Samples at each time-point were collected from at least thirty ears and pooled to represent the line characteristics of X178. Two sub-samples for replication in the microarray analysis were randomly drawn. Samples from two consecutive time-points were paired and labeled using different fluorescent dyes (Cy3 and Cy5) and hybridized in the same array. A loop design was applied for running the microarray. Two replicates of each pair of samples were carried out to test both the reproducibility and quality of the chip hybridizations.
Project description:We performed a molecular characterization of the maize small kernel mutant with endosperm developmental deficiency phenotypes.To elucidate how SMK8 affects kernel development, we performed RNA sequencing (RNA-seq), and the results revealed numerous differentially expressed genes related to storage proteins and starch biosynthesis and biosynthesis of amino acids.
Project description:Modern maize was domesticated from Teosinte parviglumis, with subsequent introgressions from Teosinte mexicana, yielding increased kernel row number, loss of the hard fruit case and dissociation from the cob upon maturity, as well as fewer tillers. Molecular approaches have identified several transcription factors involved in the development of these traits, yet revealed that a complex regulatory network is at play. MaizeCODE deploys ENCODE strategies to catalog regulatory regions in the maize genome, generating histone modification and transcription factor ChIP-seq in parallel with transcriptomics datasets in 5 tissues of 3 inbred lines which span the phenotypic diversity of maize, as well as the teosinte inbred TIL11. Integrated analysis of these datasets resulted in the identification of a comprehensive set of regulatory regions in each inbred, and notably of distal enhancers which were differentiated from gene bodies by their lack of H3K4me1. Many of these distal enhancers expressed noncoding enhancer RNAs bi-directionally, reminiscent of “super enhancers” in animal genomes. We show that pollen grains are the most differentiated tissue at the transcriptomic level, and share features with endosperm that may be related to McClintock’s chromosome breakagefusion-bridge cycle. Conversely, ears have the least conservation between maize and teosinte, both in gene expression and within regulatory regions, reflecting conspicuous morphological differences selected during domestication. The identification of molecular signatures of domestication in transcriptional regulatory regions provides a framework for directed breeding strategies in maize.
Project description:Two maize inbred lines, DAN3130 and JI63, with different patterns of folate accumulation and different total folate contents in mature kernels were used to investigate the transcriptional regulation of folate metabolism during late stages of kernel formation by comparative transcriptome analysis; The fresh kernel samples of each inbred line were collected on DAP 24, DAP 35 days, respectively. Mature kernel samples were harvested after all the plants turned yellow. Three biological replicates of each sample were collected, and total RNA with high quality was pooled and sent for sequencing. Total RNA of high quality was pooled for transcriptome analysis, and raw RNA-seq data of DAP 24, DAP35 and mature kernels for both two inbred lines were obtained. The folate accumulation during DAP 24 to mature kernels could be controlled by circumjacent pathways of folate biosynthesis, such as pyruvate metabolism, glutamate metabolism and serine/glycine metabolism. In addition, the folate variation between these two inbred lines was related to those genes among folate metabolism, such as genes in the pteridine branch, ρ-ABA branch, serine/THF/5-M-THF cycle and the conversion of tetrahydrofolate monoglutamate to tetrahydrofolate polyglutamate; The findings provided insight into folate accumulation mechanisms during maize kernel formation to promote folate biofortification.
Project description:Maize kernels are susceptible to infection by the opportunistic pathogen Aspergillus flavus. Infection results in reduction of grain quality and contamination of kernels with the highly carcinogenic mycotoxin, aflatoxin. To understand host response to infection by the fungus, transcription of approximately 9,000 maize genes were monitored during the host-pathogen interaction with a custom-designed Affymetrix GeneChip® DNA array. More than 1,000 maize genes were found differentially expressed at a fold change of 2 or greater. This included the up regulation of defense-related genes and signaling pathways. Transcriptional changes also were observed in primary metabolism genes. Starch biosynthetic genes were down regulated during infection, while genes encoding maize hydrolytic enzymes, presumably involved in the degradation of host reserves, were up regulated. These data indicate that infection of the maize kernel A. flavus induced metabolic changes in the kernel, including the production of a defense response, as well as a disruption in kernel development.
Project description:We explored the gene expression profiles of developing maize kernel by RNA sequencing. Our purpose was to explore the sequence diversity across the inbred lines, especially in the gene regions, and to discover the gene regulatory networks employed in immature maize kernels.
Project description:Modern maize was domesticated from Teosinte parviglumis, with subsequent introgressions from Teosinte mexicana, yielding increased kernel row number, loss of the hard fruit case and dissociation from the cob upon maturity, as well as fewer tillers. Molecular approaches have identified several transcription factors involved in the development of these traits, yet revealed that a complex regulatory network is at play. MaizeCODE deploys ENCODE strategies to catalog regulatory regions in the maize genome, generating histone modification and transcription factor ChIP-seq in parallel with transcriptomics datasets in 5 tissues of 3 inbred lines which span the phenotypic diversity of maize, as well as the teosinte inbred TIL11. Integrated analysis of these datasets resulted in the identification of a comprehensive set of regulatory regions in each inbred, and notably of distal enhancers which were differentiated from gene bodies by their lack of H3K4me1. Many of these distal enhancers expressed noncoding enhancer RNAs bi-directionally, reminiscent of “super enhancers” in animal genomes. We show that pollen grains are the most differentiated tissue at the transcriptomic level, and share features with endosperm that may be related to McClintock’s chromosome breakagefusion-bridge cycle. Conversely, ears have the least conservation between maize and teosinte, both in gene expression and within regulatory regions, reflecting conspicuous morphological differences selected during domestication. The identification of molecular signatures of domestication in transcriptional regulatory regions provides a framework for directed breeding strategies in maize.
Project description:Modern maize was domesticated from Teosinte parviglumis, with subsequent introgressions from Teosinte mexicana, yielding increased kernel row number, loss of the hard fruit case and dissociation from the cob upon maturity, as well as fewer tillers. Molecular approaches have identified several transcription factors involved in the development of these traits, yet revealed that a complex regulatory network is at play. MaizeCODE deploys ENCODE strategies to catalog regulatory regions in the maize genome, generating histone modification and transcription factor ChIP-seq in parallel with transcriptomics datasets in 5 tissues of 3 inbred lines which span the phenotypic diversity of maize, as well as the teosinte inbred TIL11. Integrated analysis of these datasets resulted in the identification of a comprehensive set of regulatory regions in each inbred, and notably of distal enhancers which were differentiated from gene bodies by their lack of H3K4me1. Many of these distal enhancers expressed noncoding enhancer RNAs bi-directionally, reminiscent of “super enhancers” in animal genomes. We show that pollen grains are the most differentiated tissue at the transcriptomic level, and share features with endosperm that may be related to McClintock’s chromosome breakagefusion-bridge cycle. Conversely, ears have the least conservation between maize and teosinte, both in gene expression and within regulatory regions, reflecting conspicuous morphological differences selected during domestication. The identification of molecular signatures of domestication in transcriptional regulatory regions provides a framework for directed breeding strategies in maize.