Project description:RNA-directed DNA methylation (RdDM) in plants is a well-characterized example of RNA interference-related transcriptional gene silencing. To determine the relationships between RdDM and heterochromatin in the repeat-rich maize (Zea mays) genome, we performed whole-genome analyses of several heterochromatic features: dimethylation of lysine 9 and lysine 27 (H3K9me2 and H3K27me2), chromatin accessibility, DNA methylation, and small RNAs; we also analyzed two mutants that affect these processes, mediator of paramutation1 and zea methyltransferase2.
Project description:The differentiation of specialized feeding sites in Zea mays root cells in response to nematode infestation involves substantial cellular reprogramming of host cells that is not well characterized at the molecular level. Expression data was generated from Zea mays root cells undergoing giant cell formation due to nematode infestation and from non-infested control root cells. Cells were laser captured 14 and 21 days after infestation. Overall design: Each time point (14 day and 21 day) consisted of three biological replicates per treatment (control root cells or giant cells). Control cells were captured from an area ~13,000,000 um2 in size and giant cells were captured from an area ~5,000,000 um2 in size. RNA samples were isolated using the PicoPure RNA Isolation Kit (Arcturus, Mountain View, USA). RNA amplifications were carried out with the NuGEN WT-Ovation Pico kit.
Project description:Epigenetic variation describes heritable differences that are not attributable to changes in DNA sequence. Methylation of cytosine residues provides a mechanism for the inheritance of epigenetic information. We have profiled the distribution of DNA methylation in the large, complex genome of Zea mays (ssp. mays). DNA methylation levels are higher near the centromeres and are generally inversely correlated with recombination and gene expression levels. However, genes that are located in non-syntenic genomic positions relative to species related closely to maize exhibit higher levels of DNA methylation independent of expression state. A comparison of the DNA methylation levels in two different inbred genotypes, B73 and Mo17, allowed for the identification of approximately 700 differentially methylated regions. The regions of differential methylation in B73 and Mo17 often occur in intergenic regions but some of these regions are located within or near genes. There is evidence that variation in DNA methylation levels can occur in genomic regions that are identical-by-descent, illustrating the potential for epigenetic variation that is not tightly linked to genetic changes. A comparison of the genotype and epigenotype in a panel of near-isogenic lines reveals evidence for epigenetic variation that is conditioned by linked regions as well as examples of epigenetic variation that is conditioned by unlinked genomic regions. Our many examples of epigenetic variation, including some without tightly linked genetic variation, have implications for plant breeding and for natural selection. Overall design: Methylation profiles in seedling tissue of the maize inbred lines B73 and Mo17. Each genotype was compared for three biological replications using a gene-focused custom 2.1M NimbleGen array.
Project description:In this study we perform a transcriptomics analysis of two maize (Zea mays) organs, roots and leaves, from plants grown in the presence of a sufficient (1000 uM) or limiting (10 uM) concentration of soil phosphate. Overall design: Duplicate root and leaf mRNA profiles for plants grown in the presence of 1000 uM or 10 uM soil phosphate.
Project description:Papain-like cysteine proteases (PLCPs) play important roles in plant defense mechanisms. Previous work identified a set of five apoplastic PLCPs (CP1A, CP1B, CP2, XCP2 and CatB) which are crucial for the orchestration of SA-dependent defense signaling and vice versa in maize (Zea mays). One central question from these findings is which mechanism is triggered by apoplastic PLCPs to induce SA-dependent defenses. By a mass spectrometry approach we discovered a novel peptide (Zip1 = Zea mays immune signaling peptide) to be enriched in apoplastic fluid upon SA treatment. Zip1 induces PR-gene expression when applied to naїve maize leaves. Moreover, it activates apoplastic PLCPs similar as SA does, suggesting Zip1 to play an important role in SA-mediated defense signaling. In vitro studies using recombinant protein showed that CP1A and CP2, but not XCP2 and CatB, release Zip1 from its pro-peptide (PROZIP1) in vitro. Strikingly, metabolite analysis showed direct induction of SA de novo synthesis by Zip1 in maize leaves. In line with this, RNA sequencing revealed that Zip1-mediated changes in maize gene expression largely resemble SA-induced responses. Consequently, Zip1 increases maize susceptibility to the necrotrophic fungal pathogen Botrytis cinerea. In summary, this study identifies the PLCP-released peptide signal Zip1, which triggers SA signaling in maize.
Project description:In this study RNA-sequencing was used to monitor gene expression changes in four tissues (meristematic zone, elongation zone, and cortex and stele of the mature zone) of maize (Zea mays L.) primary roots in response to water deficit to gain a better understanding of the mechanisms underlying drought tolerance.