Biology subjects

Nath, V. S.

Publications and source records attributed to Nath, V. S..

3 recordsLinked to original sources

bioRxiv2025

NCR13 peptide protects soybean against Cercospora sojina by multiple modes of action and additive interaction with chemical fungicides

Frogeye Leaf Spot (FLS) disease, caused by a fungal pathogen Cercospora sojina, is a serious threat to soybean production globally. The control of FLS is facing a major challenge due to the rapid emergence of pathogen resistance to Quinone outside Inhibitor (QoI) fungicides. Effective long-term management of FLS in soybean calls for the discovery of antifungal compounds with new modes of action (MoA), durability and safety. Here, we showed that chickpea nodule-specific cysteine-rich peptide, NCR13_Peptide Folding Variant1 (NCR13_PFV1), exhibited antifungal activity against QoI-sensitive and -resistant field isolates of C. sojina at nanomolar concentrations representing the first antifungal NCR peptide reported effective against C. sojina. Spray-application of this peptide showed no phytotoxicity and effectively protected soybean against FLS. When combined with the QoI fungicide azoxystrobin, NCR13_PFV1 provided additive control of FLS. NCR13_PFV1 induced plasma membrane disruption and production of reactive oxygen species (ROS) in C. sojina. NCR13_PFV1 was rapidly internalized into fungal cells where it accumulated in the cytoplasm, localized inside nucleus, bound to fungal ribosomal RNA and inhibited protein translation in vivo. RNA-seq studies revealed the upregulation of several genes encoding heme binding proteins in peptide-challenged C. sojina. Notably, iron supplementation in the growth medium reduced the peptide-induced ROS and antifungal activity, revealing the importance of iron homeostasis in protection or recovery of C. sojina from oxidative stress. Overall, NCR13_PFV1 with multiple MoA holds potential as a bio-fungicide for FLS control complementing conventional QoI fungicides and overcoming fungicide resistance in C. sojina.

plant biology↗

bioRxiv2024

Modes of action and bio-fungicide potential of peptides derived from the bi-domain plant defensin MtDef5

Medicago truncatula bi-domain defensin MtDef5 exhibits antifungal activity at sub-micromolar concentrations against some fungal pathogens. It comprises two single-domain defensins, MtDef5A and MtDef5B, connected with a linker APKKVEP. MtDef5B is a more potent antifungal defensin than MtDef5A. We identified amino acid residues important for antifungal activity of MtDef5B and elucidated its modes of action (MoA). MtDef5B inhibited spore germination of Botrytis cinerea (Bc) at low micromolar concentrations. However, it did not inhibit spore germination of Colletotrichum gloeosporioides (Cg). MtDef5B permeabilized the plasma membrane, induced reactive oxygen species and traveled to the nucleoli in germlings of Bc. Furthermore, a carboxy-terminal MtDef5A-derived GMA5AC peptide was selected for mutagenesis because of its lower cationicity than the corresponding MtDef5B-derived peptide. GMA5AC inhibited spore germination of Bc, but not of Cg. However, GMA5AC_V2, a variant of GMA5AC, inhibited spore germination of Cg and exhibited multi-faceted MoA. Spray-application of GMA5AC_V2 on the leaves of pepper plants demonstrated preventive and curative control of the gray mold disease. Furthermore, when applied topically on tomato fruits pre-inoculated with the pathogen Cg, this peptide reduced anthracnose disease symptoms. This study highlights the potential of short chain defensin-derived peptides for management of fungal diseases. HighlightsThe bi-domain MtDef5-derived antifungal peptides exhibit multiple modes of action and confer resistance against the gray mold and anthracnose diseases in pepper plants and tomato fruits, respectively.

pathology↗

bioRxiv2022

The multifaceted roles of R2R3 transcription factor HlMYB7 in the regulation of flavonoid and bitter acids pathways, development and biotic stress in hop (Humulus lupulus L.)

Hop (Humulus lupulus) biosynthesizes the highly economically valuable secondary metabolites, which include flavonoids, bitter acids, polyphenols and essential oils. These compounds have important pharmacological properties and are widely implicated in the brewing industry owing to bittering flavor, floral aroma and preservative activity. Our previous studies documented that ternary MYB-bHLH-WD40 (MBW) and binary WRKY1-WD40 (WW) protein complexes transcriptionally regulate the accumulation of bitter acid (BA) and prenylflavonoids (PF). In the present study, we investigated the regulatory functions of the R2R3-MYB repressor HlMYB7 transcription factor, which contains a conserved N-terminal domain along with the repressive motif EAR, in regulating the PF- and BA-biosynthetic pathway and their accumulation in hop. Constitutive expression of HlMYB7 resulted in transcriptional repression of structural genes involved in the terminal steps of biosynthesis of PF and BA, as well as stunted growth, delayed flowering, and reduced tolerance to viroid infection in hop. Furthermore, yeast two-hybrid and transient reporter assays revealed that HlMYB7 targets both PF and BA pathway genes and suppresses MBW and WW protein complexes. Heterologous expression of HlMYB7 leads to down-regulation of structural genes of flavonoid pathway in Arabidopsis thaliana, including a decrease in anthocyanin content in Nicotiana tabacum. The combined results from functional and transcriptomic analyses highlight the important role of HlMYB7 in fine-tuning and balancing the accumulation of secondary metabolites at the transcriptional level, thus offer a plausible target for metabolic engineering in hop.

plant biology↗