Pathogenicity of Metarhizium anisopliae isolates on Nezara viridula and Dichelops melacanthus in wheat crop

<div><p>ABSTRACT: Bugs such as Nezara viridula (Linnaeus) and Dichelops melacanthus (Dallas) are considered the main insect pests of wheat crop in Brazil. The use of the entomopathogenic fungus Metarhizium anisopliae (Metschnikoff) may be an alternative for the management of these insects in the crop. The objective of this work was to verify the pathogenicity of different isolates of M. anisopliae on adults of N. viridula and D. melacanthus under laboratory and greenhouse conditions. In the laboratory, isolates 05RA, 11RA, 08RA and 02RA were obtained from N. viridula and D. melacanthus infested with M. anisopliae. Also, a high pathogenicity (100% of mortality) of both species was recorded in a bioassay of the topical application 8 Days After Application (DAA). However, compared to the other isolates, the 08RA isolate showed the highest pathogenicity in a shorter time interval for N. viridula (Mean Time “MT” = 2.8 days) and D. melacanthus (MT = 4.0 days). Under greenhouse conditions, the 08RA isolate provided a mortality of 44.9% (N. viridula) and 35.7% (D. melacanthus) in the same evaluation period. However, at 14 DAA, the mortality was 100% for both species, with the MT values of N. viridula and D. melacanthus being obtained at 8 days and 10 days, respectively. The fungus M. anisopliae is a promising alternative for the control of adult N. viridula and D. melacanthus in wheat crop.</p></div

SUVR5 and LDL1 act together in a repressor complex.

<p>a, analysis of the late flowering phenotype of <i>ldl1 ldl2</i> mutants and its complementation by the tagged LDL1 transgene measured by scoring number of leaves at bolting; b, table showing the mass spectrometry analyses of LDL1 affinity purifications; c, picture showing the late flowering phenotype of <i>suvr5, ldl1 ldl2</i> and <i>suvr5 ldl1 ldl2</i> plants; d, analysis of the late flowering phenotype by scoring number of leaves at bolting; e, box plot showing the expression level (in RPKM) of the 270 genes upregulated in <i>suvr5</i> and <i>ldl1 ldl2</i> (over 4 fold and P<0.01 for both, <i>suvr5</i>/Col-0 and <i>ldl1 ldl2</i>/Col-0) in Col-0, <i>suvr5, ldl1 ldl2</i> and the triple <i>suvr5 ldl1 ldl2</i> mutants, showing the epistatic relationship between the mutants.</p

The SET-Domain Protein SUVR5 Mediates H3K9me2 Deposition and Silencing at Stimulus Response Genes in a DNA Methylation–Independent Manner

<div><p>In eukaryotic cells, environmental and developmental signals alter chromatin structure and modulate gene expression. Heterochromatin constitutes the transcriptionally inactive state of the genome and in plants and mammals is generally characterized by DNA methylation and histone modifications such as histone H3 lysine 9 (H3K9) methylation. In <em>Arabidopsis thaliana,</em> DNA methylation and H3K9 methylation are usually colocated and set up a mutually self-reinforcing and stable state. Here, in contrast, we found that SUVR5, a plant Su(var)3–9 homolog with a SET histone methyltransferase domain, mediates H3K9me2 deposition and regulates gene expression in a DNA methylation–independent manner. SUVR5 binds DNA through its zinc fingers and represses the expression of a subset of stimulus response genes. This represents a novel mechanism for plants to regulate their chromatin and transcriptional state, which may allow for the adaptability and modulation necessary to rapidly respond to extracellular cues.</p> </div

Proposed model for SUVR5 function.

<p>SUVR5 is part of a multimeric complex including LDL1 that recognizes gene promoters and represses their expression by altering their epigenetic status.</p

SUVR5-specific H3K9me2 deposition correlates with the zinc finger domain binding and promotes gene silencing.

<p>a, genome browser view of a region in the arms of chromosome 1. H3K9me2 data is represented as log2 ratios from 0 to 2.5. Gene models correspond to TAIR8 protein-coding genes (PCG) and are shown for the plus or minus strand of the genome; b, Venn diagram representation of the number of H3K9me2 decreased regions defined for <i>suvr5</i> mutants that are specific to them or overlap with the ones in <i>kyp suvh5 suvh6</i>; c, box plot showing the levels of H3K9me2 in the genes that have gSELEX signal in their upstream 3 Kb region; d, meta-analysis of H3K9me2 levels on <i>suvr5-1</i> and Col-0 over the <i>suvr5</i>-specific H3K9me2 decreased regions; e, meta analysis of CG, CHG and CHH DNA methylation levels in <i>suvr5-1</i> and Col-0 over the <i>suvr5</i>-specific H3K9me2 decreased regions.</p

SUVR5 zinc finger domain binds specific sequences of DNA that map to the promoters of genes.

<p>a, Domain structure of SUVR5 (Poly-Asp: domain of unknown function rich in Asp residues); b, enriched motifs identified in the sequencing data obtained from the SELEX experiments; c, meta-gene analysis of the genomic SELEX (gSELEX) reads showing preferential binding of the SUVR5 zinc finger domain to the 3 Kb region upstream of protein coding genes (PCG). The results obtained after exponential selection of the binding sites for 9 cycles are shown (×9) in contrast with the results obtained after only one cycle of enrichment (×1), included as control; d, mobility shift assay with increasing amounts of GST-zinc finger domain (100, 250 and 500 ng) added to a binding reaction with either an unspecific oligonucleotide probe or a specific probe including the identified binding motif sequence.</p

SUVR5 is redundant with KYP/SUVH5/SUVH6 in controlling H3K9me2 accumulation in heterochromatin.

<p>a, Chromosome 1 view of the log2 ratio of H3K9me2 signal in <i>suvr5</i> mutants vs. Col-0 (red), and the log2 ratio of <i>kyp suvh5 suvh6</i> triple mutants vs. Col-0 (black); b, Chromosome 1 distribution of DNA methylation in <i>suvr5-1</i> and Col-0; c, meta-analysis of H3K9me2 levels on <i>suvr5</i> and <i>kyp suvh5 suvh6</i> mutants vs. Col-0 over TEs; d, meta analysis of CG, CHG and CHH DNA methylation levels in <i>suvr5-1</i> and Col-0 over TEs. (green = CG, blue = CHG, red = CHH; light colors are Col-0, and dark colors are <i>suvr5-1</i>).</p