Constitutive BoHAK5 expression and early robust induction of salicylic acid biosynthesis genes as candidates to explain the tolerance of broccoli to limiting potassium
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ABSTRACT: Potassium is vital for optimum plant growth and crop yield and so is an important component of fertilizers. However, our knowledge of the physiological and molecular response in response to limiting potassium conditions is incomplete. Here we performed a detailed transcriptomic analysis of the model plant, Arabidopsis and the crop plant, broccoli to compare and contrast the response to this abiotic stress. Our results show that broccoli plants lose potassium at a much slower rate than Arabidopsis. This may be explained by the high levels of expression of the BoHAK5 gene. Both Arabidopsis and broccoli showed characteristic responses observed in other plant species, related to oxidative stress and hypoxia and jasmonic, salicylic and abscisic acid signaling. In broccoli, we also observed alterations in the gene expression patterns of enzymes and in the levels of intermediates involved in the biosynthesis of glucosinolates, which are important molecules contributing to the added nutritional value of broccoli. Lastly, we provide evidence for concomitant alterations in the transport of several other ions, such as iron, phosphate and nitrate. Our data help to characterize the response of broccoli to limiting potassium conditions and may provide insights for the development of varieties of broccoli with reduced fertilization requirements.
Project description:Purpose: The goals of this study are to analyze the transcriptome of five time point in broccoli seed germination and sprout development and to find the putative glucosinolate metabolism genes in the stage. Methods: Total mRNA of germinated seeds, 3 day cotyledons, 7 day botyledons, 11 day cotyledons and 11 day euphyllas of wild-type broccoli were harvested. Each sample was harvested in three independent biological replicates with equal weight and subsequently pooled together for sequencing. The sequence reads that passed quality filters were de novo assembled using VELVET followed by OASES. Then the assembled unigenes were used for the abundance and functional analysis. Results: A total of ~85million 251bp reads were obtained. After de novo assembly and searching the assembled transcripts against the Arabidopsis thaliana and Nr databases, 19,441 top-hit transcripts were clustered as unigenes with an average length of 2,133bp. These unigenes were classified according to their putative functional categories. Cluster analysis of total unigenes with similar expression patterns and differentially expressed unigenes among different tissues,as well as transcription factor analysis were performed. We identified 25 putative glucosinolate metabolismgenes sharing 62.04-89.72% nucleotide sequence identity with the Arabidopsis orthologs. This established a broccoli glucosinolate metabolic pathway with high colinearity to Arabidopsis. Many of the biosynthetic and degradation genes showed higher expression after germination than in seeds; especially the expression of the myrosinaseTGG2 was 20-130 times higher.These results along with the previous reports that glucosinolate concentration decreased exponentially once after germination indicate the breakdown products of glucosinolates may play important roles in broccoli seed germination and sprout development. Conclusion: Our study provides the largest genetic resource of broccoli to date. These data will pave the way for further studies and genetic engineering of broccoli sprouts to develop functional vegetables containing high levels of the anticarcinogenic glucosinolates. They will also provide new insight into the genomic research of this species and its relatives.
Project description:Purpose: The goals of this study are to analyze the transcriptome of five time point in broccoli seed germination and sprout development and to find the putative glucosinolate metabolism genes in the stage. Methods: Total mRNA of germinated seeds, 3 day cotyledons, 7 day botyledons, 11 day cotyledons and 11 day euphyllas of wild-type broccoli were harvested. Each sample was harvested in three independent biological replicates with equal weight and subsequently pooled together for sequencing. The sequence reads that passed quality filters were de novo assembled using VELVET followed by OASES. Then the assembled unigenes were used for the abundance and functional analysis. Results: A total of ~85million 251bp reads were obtained. After de novo assembly and searching the assembled transcripts against the Arabidopsis thaliana and Nr databases, 19,441 top-hit transcripts were clustered as unigenes with an average length of 2,133bp. These unigenes were classified according to their putative functional categories. Cluster analysis of total unigenes with similar expression patterns and differentially expressed unigenes among different tissues,as well as transcription factor analysis were performed. We identified 25 putative glucosinolate metabolismgenes sharing 62.04-89.72% nucleotide sequence identity with the Arabidopsis orthologs. This established a broccoli glucosinolate metabolic pathway with high colinearity to Arabidopsis. Many of the biosynthetic and degradation genes showed higher expression after germination than in seeds; especially the expression of the myrosinaseTGG2 was 20-130 times higher.These results along with the previous reports that glucosinolate concentration decreased exponentially once after germination indicate the breakdown products of glucosinolates may play important roles in broccoli seed germination and sprout development. Conclusion: Our study provides the largest genetic resource of broccoli to date. These data will pave the way for further studies and genetic engineering of broccoli sprouts to develop functional vegetables containing high levels of the anticarcinogenic glucosinolates. They will also provide new insight into the genomic research of this species and its relatives. Wild-type broccoli mRNA profiles of seeds, 3 day cotyledons, 7 day botyledons, 11 day cotyledons and 11 day euphyllas were generated by deep sequencing, three biological replicates pooling together for each tissue, using Illumina Myseq platform.
Project description:EMF2 genes play an important function in inhibiting reproductive programs during vegetative stage of plant development. We knocked down the expression of endogenous EMF2 genes in broccoli by introduing a 35S::antisenseBoEMF2.1 contruct. The transgenic broccoli with knocking-down expression of endogenous EMF2s showed aberrant phenotypes during development. We used microarrays to study the global programme of gene expression and to identified genes misexpressed in broccoli with knocking-down expression of endogenous EMF2 genes
Project description:EMF2 genes play an important function in inhibiting reproductive programs during vegetative stage of plant development. We knocked down the expression of endogenous EMF2 genes in broccoli by introduing a 35S::antisenseBoEMF2.1 contruct. The transgenic broccoli with knocking-down expression of endogenous EMF2s showed aberrant phenotypes during development. We used microarrays to study the global programme of gene expression and to identified genes misexpressed in broccoli with knocking-down expression of endogenous EMF2 genes 11-day-old seedlings of broccoli harboring the empty vector pCAMBIA1380 and that harboring 35S::antisenseBoEMF2.1 (asBoEMF2.1) were used for RNA extraction and hybridization on Affymetrix microarrays.
Project description:The associated files are mass spec data from individual fractions of mixed-bed ion exchange fractionations of native extract made from broccoli plant leaves (Brassica oleracea var. italica).
Project description:Both exogenously supplied and transgenic induced cytokinin production can effectively delay senescence of broccoli florets during postharvest storage. However, a substantial comparison between the mechanisms of these two treatments on delaying broccoli florets senescence was absent. Here, we conduct microarray analysis on broccoli florets of N6-benzylaminopurine treated and ipt-transgenic broccoli that harbor a senescence-associated-gene promoter triggering isopentenyltransferase gene expression during postharvest storage.
Project description:Isothiocyanates (ITCs) are degradation products of the plant secondary metabolites glucosinolates (GSLs) and are known to affect human health as well as plant herbivores and pathogens. To investigate the processes engaged in plants upon exposure to isothiocyanate we performed a genome scale transcriptional profiling of Arabidopsis thaliana at different time points in response to an exogenous treatment with allyl-isothiocyanate.
Project description:We report the application of RNA-seq to uncover the underlying mechanism of 10 mM calcium chloride spray on broccoli seedlings (Brassica oleracea var. italic) boosted the hypocotyl elongation and delayed the senescence.
Project description:Background: Over application of phosphate fertilizers in modern agriculture contaminates waterways and disrupts natural ecosystems. Nevertheless, this is a common practice among farmers, especially in developing countries as abundant fertilizers are believed to boost crop yields. The study of plant phosphate metabolism and its underlying genetic pathways is key to discovering methods of efficient fertilizer usage. The work presented here describes the first genome-wide resource on the molecular dynamics underpinning the response and recovery in roots and shoots of Arabidopsis thaliana to phosphate-starvation. Results: Genome-wide profiling revealed minimal overlap between root and shoot transcriptomes suggesting two independent phosphate-starvation regulons. Novel gene expression patterns were detected for over 1000 candidates and were classified as either initial, persistent, or latent responders. Comparative analysis to AtGenExpress identified novel cohorts of genes co-regulated across multiple stimuli. The hormone ABA displayed a dominant role in regulating many phosphate-responsive candidates. Analysis of co-regulation enabled the determination of primary versus redundant members of closely related gene families with respect to phosphate-starvation. Thus, among others, we show that PHO1 acts in shoot, whereas PHO1;H1 is likely the primary regulator in root. Conclusion: Our results uncover a much larger, staged responses to phosphate-starvation than previously described. To our knowledge, this work describes the highest resolution of genome-wide data on plant nutrient stress to date. 2 tissues X 3 treatments X 3 biological replicates
Project description:Background: Over application of phosphate fertilizers in modern agriculture contaminates waterways and disrupts natural ecosystems. Nevertheless, this is a common practice among farmers, especially in developing countries as abundant fertilizers are believed to boost crop yields. The study of plant phosphate metabolism and its underlying genetic pathways is key to discovering methods of efficient fertilizer usage. The work presented here describes the first genome-wide resource on the molecular dynamics underpinning the response and recovery in roots and shoots of Arabidopsis thaliana to phosphate-starvation. Results: Genome-wide profiling revealed minimal overlap between root and shoot transcriptomes suggesting two independent phosphate-starvation regulons. Novel gene expression patterns were detected for over 1000 candidates and were classified as either initial, persistent, or latent responders. Comparative analysis to AtGenExpress identified novel cohorts of genes co-regulated across multiple stimuli. The hormone ABA displayed a dominant role in regulating many phosphate-responsive candidates. Analysis of co-regulation enabled the determination of primary versus redundant members of closely related gene families with respect to phosphate-starvation. Thus, among others, we show that PHO1 acts in shoot, whereas PHO1;H1 is likely the primary regulator in root. Conclusion: Our results uncover a much larger, staged responses to phosphate-starvation than previously described. To our knowledge, this work describes the highest resolution of genome-wide data on plant nutrient stress to date. 6 Sample types, 3 replicates each