Biology subjects

Karki, S. J.

Publications and source records attributed to Karki, S. J..

3 recordsLinked to original sources

bioRxiv2026

Biocontrol efficacy of 2-pyrroldione-5-carboxylic acid (2Py-5CA), an antifungal bioactive macromolecule from the endophyte Penicillium oxalicum, against Ramularia collo-cygni in barley

Global crop production suffers significant losses (23%) due to disease caused by fungal pathogens. Biocontrol agents may be sustainable alternatives to fungicides for disease management. Ramularia leaf spot (RLS), caused by Ramularia collo-cygni (RCC), is a widespread disease of barley (Hordeum vulgare). Two Penicillium oxalicum isolates identified from a collection of endophytes from wild barley, suppress development of R. collo-cygni and exhibit functional plant growth attributes in vitro. Analysis of the P. oxalicum culture filtrate revealed antifungal activity common to both isolates. An untargeted metabolomics (LC-MS/MS) approach uncovered the secondary metabolite profile of the P. oxalicum endophytes including the identification of 2Py-5CA as an antifungal. AntiSMASH-based genome mining identified a non-ribosomal peptide synthetase (NRPSs) biosynthetic gene cluster in P. oxalicum responsible for producing paraherquamide and ultimately the antifungal 2Py-5CA. In vitro studies demonstrated that 2Py-5CA can also suppress growth of the cereal pathogens; Zymoseptoria tritici, Pyrenophora teres, Fusarium graminearum and the horticultural pathogen, Botrytis cinerea disrupting the growth of pathogenic fungal hyphae and spore structure development. Finally, 2Py-5CA reduced RLS symptoms when sprayed on barley seedlings. Therefore 2Py-5CA has potential as a biofungicide to combat fungal crop pathogens. Graphic O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=55 SRC="FIGDIR/small/701693v1_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@9d1bf2org.highwire.dtl.DTLVardef@95bc91org.highwire.dtl.DTLVardef@8f0313org.highwire.dtl.DTLVardef@1130b0c_HPS_FORMAT_FIGEXP M_FIG C_FIG

plant biology↗

bioRxiv2024

The Zymoseptoria tritici effector Zt-11 contributes to aggressiveness in wheat

Zymoseptoria tritici is an ascomycete fungus and the causal agent of Septoria tritici leaf blotch (STB) in wheat. Z. tritici secretes an array of effector proteins that are likely to facilitate host infection, colonisation and pycnidia production. In this study we demonstrate a role for Zt-11 as a Z. tritici effector during disease progression. Zt-11 is upregulated during the transition of the pathogen from the biotrophic to necrotrophic phase of wheat infection. Deletion of Zt-11 delayed disease development in wheat, reducing the number and size of pycnidia, as well as the number of macropycnidiospores produced by Z. tritici. This delayed disease development by the {Delta}Zt-11 mutants was accompanied by a lower induction of PR genes in wheat, when compared to infection with wildtype Z. tritici. Overall, these data suggest that Zt-11 plays a role in Z. tritici aggressiveness and STB disease progression possibly via a salicylic acid associated pathway.

plant biology↗

bioRxiv2021

Genome-wide identification of the oat MLO family and identification of a candidate AsMLO associated with powdery mildew susceptibility

Blumeria graminis f. spp. avenae is the causal agent of powdery mildew disease in oats (Avena sativa). It is the most significant limiting factor to oat production, with yield losses ranging from 5%-40%, during high disease pressure conditions. Certain members of the Mildew Locus O (MLO) gene family have been shown to act as powdery mildew susceptibility factors in many different plant species. A loss-of-function mutation of specific MLO genes confers broad-spectrum resistance against powdery mildew pathogens. Potential MLO candidates have not yet been identified in oats. In this study, we identified oat MLOs by querying 341 known MLO protein sequences against the publicly available oat genome. 11 MLO-like sequences were identified in oats. Phylogenetic analysis grouped these candidates into four different clades, one of which, AsMLO1 was grouped together with other cereal MLOs functionally known to contribute to powdery mildew susceptibility. AsMLO1 showed the highest similarity to the known powdery mildew-associated MLO proteins from wheat and barley. Gene expression analysis revealed AsMLO1 expression is up regulated at 12 hours post-infection with Bga and was inferred to be a candidate gene associated with powdery mildew susceptibility in oats. These results are an important step towards more durable strategies to control powdery mildew incidence and severity in oats.

plant biology↗