Biology subjects

Mengiste, T.

Publications and source records attributed to Mengiste, T..

4 recordsLinked to original sources

bioRxiv2026

Sorghum ANTHRACNOSE RESISTANCE GENE3 Is a Non-Coding RNA That Confers Fungal Resistance through Enhanced Cell Death

The fungal pathogen Colletotrichum sublineola is a major constraint to sorghum production. The sorghum genotype IS18760 is resistant to multiple C. sublineola strains, but the genetic basis of this resistance is unknown. Bulk segregant analysis using whole-genome resequencing of a biparental mapping population identified a major resistance locus, designated ANTHRACNOSE RESISTANCE GENE LOCUS 3 (ARG3), associated with extensive cell death. Fine mapping delimited the ARG3 locus to a 30 kb interval containing three predicted protein-coding genes and one unannotated non-coding RNA gene. Among these, only the non-coding RNA gene showed consistent sequence polymorphisms between resistant and susceptible lines and elevated pathogen-induced expression in the resistant parent, suggesting that it underlies ARG3-mediated resistance. Regions syntenic to ARG3 across grass species contain conserved non-coding sequences enriched for H3K27me3 and H2A.Z chromatin marks, suggesting a conserved regulatory function. The resistance allele is absent from a 111-line sorghum pangenome. The resistant sorghum line harboring ARG3 and the corresponding avirulent pathogen strain originate from the same geographic region, suggesting co-evolution between host resistance and a prevalent pathogen strain. Phylogenetic analysis suggests that loss of resistance in susceptible lines may relate to insertion of a 12.4 kb repetitive sequence. Importantly, silencing of the ARG3 transcript in the resistant parental line abrogated resistance to C. sublineola, confirming that ARG3 non-coding RNA gene underlies the fungal resistance mediated by the ARG3 locus in IS18760. These lines of evidence show that ARG3 is an important target for resistance breeding and provide new insight into non-coding RNA-mediated disease resistance.

plant biology↗

bioRxiv2022

ANTHRACNOSE RESISTANCE GENE2 confers fungal resistance in sorghum

Sorghum is an important food and feed crop globally; its production is hampered by anthracnose disease caused by the fungal pathogen Colletotrichum sublineola (Cs). Here, we report identification and characterization of ANTHRACNOSE RESISTANCE GENE 2 (ARG2) encoding a nucleotide-binding leucine-rich repeat (NLR) protein that confers race-specific resistance to Cs strains. ARG2 is one of a cluster of several NLR genes in the sorghum differential line SC328C that is resistant to some Cs strains. This cluster shows structural and copy number variations in different sorghum genotypes. Different sorghum variants carrying independent ARG2 alleles provided the genetic validation for the identity of the ARG2 gene. ARG2 expression is induced by Cs, and chitin induce ARG2 expression in resistant but not in susceptible lines. ARG2-mediated resistance is accompanied by higher expression of defense and secondary metabolite genes at early stages of infection, and anthocyanin and zeatin metabolisms are upregulated in resistant plants. Interestingly, ARG2 localizes to the plasma membrane when transiently expressed in Nicotiana benthamiana. Importantly, ARG2 plants produced higher shoot dry matter than near-isogenic lines carrying the susceptible allele suggesting absence of an ARG2 associated growth trade-off. Further, ARG2-mediated resistance is stable at a wide range of temperatures. Our observations open avenues for resistance breeding and for dissecting mechanisms of resistance.

plant biology↗

bioRxiv2022

Improved pathogen and stress tolerance in tomato mutants of SET domain histone 3 lysine methyltransferases

Histone lysine methylations (HLMs) are implicated in control of gene expression in different eukaryotes. However, the role of HLMs in regulating desirable crop traits and the enzymes involved in these modifications are poorly understood. We studied the functions of tomato histone H3 lysine methyltransferases Set Domain Group 33 (SDG33) and SDG34 in biotic and abiotic stress responses. SDG33 and SDG34 mutants were altered in H3K36 and H3K4 methylations, and expression of genes involved in diverse processes and responses to biotic and abiotic stimuli. The double but not the single mutants show resistance to the fungal pathogen Botrytis cinerea. Interestingly, single mutants were tolerant to drought and the double mutant showed superior tolerance consistent with independent and additive functions. Mutants maintained higher water status during drought and improved recovery and survival after lapse of drought. Notably, diminution of H3K4 and H3K36 trimethylation and expression of negative regulators in challenged plants contributes to stress tolerance of the mutants. Mutations in SDG33 and SDG34 remove predisposition to biotic and abiotic stress by disrupting permissive transcriptional context promoting expression of negative regulatory factors. These allows improvement of stress and pathogen tolerance through modification of histone epigenetic marks.

plant biology↗

bioRxiv2020

The Botrytis cinerea Crh transglycosylae is a cytoplasmic effector triggering plant cell death and defense response

Crh proteins catalyze crosslinking of chitin and glucan polymers in the fugal cell wall. We revealed a novel and unexpected role of Botrytis cinerea BcCrh1 as a cytoplasmic effector and elicitor of plant defense. During saprophytic growth the BcCrh1 protein is localized in vacuoles and ER. Upon plant infection the protein accumulates to high levels in infection cushions, it is then secreted to the apoplast and translocated into plant cells, where it induces cell death and defense responses. Two regions of 53 and 35 amino acids were found sufficient for protein uptake and cell death induction, respectively. Dimerization of BcCrh proteins was necessary for the transglycosylation activity and proper fungal development, while the monomeric proteins was sufficient for induction of cell death. Arabidopsis lines expressing the bccrh1 gene had reduced sensitivity to B. cinerea, demonstrating the potential use of the protein in plant immunization against necrotrophic pathogens.

microbiology↗