This page has only limited features, please log in for full access.

Unclaimed
Priyanka Reddy
Agriculture Victoria Research, AgriBio, 5 Ring Road, Bundoora, VIC 3083, Australia

Basic Info

Basic Info is private.

Honors and Awards

The user has no records in this section


Career Timeline

The user has no records in this section.


Short Biography

The user biography is not available.
Following
Followers
Co Authors
The list of users this user is following is empty.
Following: 0 users

Feed

Journal article
Published: 17 July 2020 in Metabolites
Reads 0
Downloads 0

Volatile phenols (VPs) derived from smoke-exposed grapes are known to confer a smoky flavor to wine. Current methods for determination of VPs in grape berries either involve complex sample purification/derivatization steps or employ two analytical platforms for free and bound VP fractions. We report here a simple gas chromatography-tandem mass spectrometry (GC-MS/MS) method for quantification of both free and bound VPs in grapes, based on optimized (1) GC-MS/MS parameters, (2) an analyte extraction procedure, and (3) phenol glycoside hydrolysis conditions. Requiring neither sample cleanup nor a derivatization step, this method is sensitive (LOD ≤ 1 ng/g berries) and reproducible (RSD < 12% for repeated analyses) and is expected to significantly reduce the sample turnover time for smoke taint detection in vineyards.

ACS Style

Zhiqian Liu; Vilnis Ezernieks; Priyanka Reddy; Aaron Elkins; Christian Krill; Kieran Murphy; Simone Rochfort; German Spangenberg. A Simple GC-MS/MS Method for Determination of Smoke Taint-Related Volatile Phenols in Grapes. Metabolites 2020, 10, 294 .

AMA Style

Zhiqian Liu, Vilnis Ezernieks, Priyanka Reddy, Aaron Elkins, Christian Krill, Kieran Murphy, Simone Rochfort, German Spangenberg. A Simple GC-MS/MS Method for Determination of Smoke Taint-Related Volatile Phenols in Grapes. Metabolites. 2020; 10 (7):294.

Chicago/Turabian Style

Zhiqian Liu; Vilnis Ezernieks; Priyanka Reddy; Aaron Elkins; Christian Krill; Kieran Murphy; Simone Rochfort; German Spangenberg. 2020. "A Simple GC-MS/MS Method for Determination of Smoke Taint-Related Volatile Phenols in Grapes." Metabolites 10, no. 7: 294.

Journal article
Published: 24 June 2020 in Microorganisms
Reads 0
Downloads 0

Asexual Epichloë spp. fungal endophytes have been extensively studied for their functional secondary metabolite production. Historically, research mostly focused on understanding toxicity of endophyte-derived compounds on grazing livestock. However, endophyte-derived compounds also provide protection against invertebrate pests, disease, and other environmental stresses, which is important for ensuring yield and persistence of pastures. A preliminary screen of 30 strains using an in vitro dual culture bioassay identified 18 endophyte strains with antifungal activity. The novel strains NEA12, NEA21, and NEA23 were selected for further investigation as they are also known to produce alkaloids associated with protection against insect pests. Antifungal activity of selected endophyte strains was confirmed against three grass pathogens, Ceratobasidium sp., Dreschlera sp., and Fusarium sp., using independent isolates in an in vitro bioassay. NEA21 and NEA23 showed potent activity against Ceratobasidium sp. and NEA12 showed moderate inhibition against all three pathogens. Crude extracts from liquid cultures of NEA12 and NEA23 also inhibited growth of the phytopathogens Ceratobasidium sp. and Fusarium sp. and provided evidence that the compounds of interest are stable, constitutively expressed, and secreted. Comparative analysis of the in vitro and in planta metabolome of NEA12 and NEA23 using LCMS profile data revealed individual metabolites unique to each strain that are present in vitro and in planta. These compounds are the best candidates for the differential bioactivity observed for each strain. Novel endophyte strains show promise for endophyte-mediated control of phytopathogens impacting Lolium spp. pasture production and animal welfare.

ACS Style

Krishni Fernando; Priyanka Reddy; Inoka K. Hettiarachchige; German C. Spangenberg; Simone J. Rochfort; Kathryn M. Guthridge. Novel Antifungal Activity of Lolium-Associated Epichloë Endophytes. Microorganisms 2020, 8, 955 .

AMA Style

Krishni Fernando, Priyanka Reddy, Inoka K. Hettiarachchige, German C. Spangenberg, Simone J. Rochfort, Kathryn M. Guthridge. Novel Antifungal Activity of Lolium-Associated Epichloë Endophytes. Microorganisms. 2020; 8 (6):955.

Chicago/Turabian Style

Krishni Fernando; Priyanka Reddy; Inoka K. Hettiarachchige; German C. Spangenberg; Simone J. Rochfort; Kathryn M. Guthridge. 2020. "Novel Antifungal Activity of Lolium-Associated Epichloë Endophytes." Microorganisms 8, no. 6: 955.

Journal article
Published: 16 June 2020 in Scientific Reports
Reads 0
Downloads 0

The complex ergot alkaloids, ergovaline and ergotamine, cause dysregulation of physiological functions, characterised by vasoconstriction as well as thermoregulatory and cardiovascular effects in grazing livestock. To assess the effect of the mycotoxins, blood pressure and heart rate of male mice were measured, and metabolite profiling undertaken to determine relative abundances of both ergotamine and its metabolic products in body and brain tissue. Ergotamine showed similar cardiovascular effects to ergovaline, causing elevations in blood pressure and reduced heart rate. Bradycardia was preserved at low-levels of ergovaline despite no changes in blood pressure. Ergotamine was identified in kidney, liver and brainstem but not in other regions of the brain, which indicates region-specific effects of the toxin. The structural configuration of two biotransformation products of ergotamine were determined and identified in the liver and kidney, but not the brain. Thus, the dysregulation in respiratory, thermoregulatory, cardiac and vasomotor function, evoked by ergot alkaloids in animals observed in various studies, could be partially explained by dysfunction in the autonomic nervous system, located in the brainstem.

ACS Style

Priyanka Reddy; Joanne Hemsworth; Kathryn M. Guthridge; Antony Vinh; Simone Vassiliadis; Vilnis Ezernieks; German C. Spangenberg; Simone J. Rochfort. Ergot alkaloid mycotoxins: physiological effects, metabolism and distribution of the residual toxin in mice. Scientific Reports 2020, 10, 9714 .

AMA Style

Priyanka Reddy, Joanne Hemsworth, Kathryn M. Guthridge, Antony Vinh, Simone Vassiliadis, Vilnis Ezernieks, German C. Spangenberg, Simone J. Rochfort. Ergot alkaloid mycotoxins: physiological effects, metabolism and distribution of the residual toxin in mice. Scientific Reports. 2020; 10 (1):9714.

Chicago/Turabian Style

Priyanka Reddy; Joanne Hemsworth; Kathryn M. Guthridge; Antony Vinh; Simone Vassiliadis; Vilnis Ezernieks; German C. Spangenberg; Simone J. Rochfort. 2020. "Ergot alkaloid mycotoxins: physiological effects, metabolism and distribution of the residual toxin in mice." Scientific Reports 10, no. 1: 9714.

Journal article
Published: 16 January 2020 in Molecules
Reads 0
Downloads 0

Lolitrem B is the most potent indole-diterpene mycotoxin produced by Epichloë festucae var. lolii (termed LpTG-1), with severe intoxication cases reported in livestock. To date, there are no in vivo metabolism studies conducted for the mycotoxin. A mouse model assay established for assessing toxicity of indole-diterpenes was used to investigate metabolic products of lolitrem B. Mice were administered lolitrem B at 0.5 and 2.0 mg/kg body weight (b.wt) intraperitoneally before body and brain tissues were collected at 6 h and 24 h post-treatment. Samples were cryoground and subjected to a biphasic or monophasic extraction. The aqueous and lipophilic phases were analysed using liquid chromatography high-resolution mass spectrometry (LC–HRMS); data analysis was performed with Compound Discoverer™ software. A total of 10 novel phase I metabolic products were identified in the lipophilic phase and their distribution in the liver, kidney and various brain regions are described. The biotransformation products of lolitrem B were found to be present in low levels in the brain. Based on structure–activity postulations, six of these may contribute towards the protracted tremors exhibited by lolitrem B-exposed animals.

ACS Style

Priyanka Reddy; Aaron Elkins; Joanne Hemsworth; Kathryn Guthridge; Simone Vassiliadis; Elizabeth Read; German Spangenberg; Simone Rochfort. Identification and Distribution of Novel Metabolites of Lolitrem B in Mice by High-Resolution Mass Spectrometry. Molecules 2020, 25, 372 .

AMA Style

Priyanka Reddy, Aaron Elkins, Joanne Hemsworth, Kathryn Guthridge, Simone Vassiliadis, Elizabeth Read, German Spangenberg, Simone Rochfort. Identification and Distribution of Novel Metabolites of Lolitrem B in Mice by High-Resolution Mass Spectrometry. Molecules. 2020; 25 (2):372.

Chicago/Turabian Style

Priyanka Reddy; Aaron Elkins; Joanne Hemsworth; Kathryn Guthridge; Simone Vassiliadis; Elizabeth Read; German Spangenberg; Simone Rochfort. 2020. "Identification and Distribution of Novel Metabolites of Lolitrem B in Mice by High-Resolution Mass Spectrometry." Molecules 25, no. 2: 372.

Journal article
Published: 13 November 2019 in Microorganisms
Reads 0
Downloads 0

Epoxy-janthitrems are a class of indole diterpenes with structural similarity to lolitrem B. Two taxa of asexual Epichloë endophytes have been reported to produce epoxy-janthitrems, LpTG-3 (Lolium perenne Taxonomic Group 3; e.g., NEA12) and LpTG-4 (e.g., E1). Epichloë epoxy-janthitrems are not well understood, the biosynthetic pathway and associated gene complement have not been described and while the literature suggests they are associated with superior protection against pasture insect pests and are tremorgenic in grazing mammals, these properties have not been confirmed using isolated and purified compounds. Whole genome sequence analysis was used to identify candidate genes for epoxy-janthitrem biosynthesis that are unique to epoxy-janthitrem producing strains of Epichloë. A gene, jtmD, was identified with homology to aromatic prenyl transferases involved in synthesis of indole diterpenes. The location of the epoxy-janthitrem biosynthesis gene cluster (JTM locus) was determined in the assembled nuclear genomes of NEA12 and E1. The JTM locus contains cluster 1 and cluster 2 of the lolitrem B biosynthesis gene cluster (LTM locus), as well as four genes jtmD, jtmO, jtm01, and jtm02 that are unique to Epichloë spp. that produce epoxy-janthitrems. Expression of each of the genes identified was confirmed using transcriptome analysis of perennial ryegrass-NEA12 and perennial ryegrass-E1 symbiota. Sequence analysis confirmed the genes are functionally similar to those involved in biosynthesis of related indole diterpene compounds. RNAi silencing of jtmD and in planta assessment in host-endophyte associations confirms the role of jtmD in epoxy-janthitrem production. Using LCMS/MS technologies, a biosynthetic pathway for the production of epoxy-janthitrems I–IV in Epichloë endophytes is proposed.

ACS Style

Emma J. Ludlow; Simone Vassiliadis; Piyumi N. Ekanayake; Inoka K. Hettiarachchige; Priyanka Reddy; Tim I. Sawbridge; Simone J. Rochfort; German C. Spangenberg; Kathryn M. Guthridge. Analysis of the Indole Diterpene Gene Cluster for Biosynthesis of the Epoxy-Janthitrems in Epichloë Endophytes. Microorganisms 2019, 7, 560 .

AMA Style

Emma J. Ludlow, Simone Vassiliadis, Piyumi N. Ekanayake, Inoka K. Hettiarachchige, Priyanka Reddy, Tim I. Sawbridge, Simone J. Rochfort, German C. Spangenberg, Kathryn M. Guthridge. Analysis of the Indole Diterpene Gene Cluster for Biosynthesis of the Epoxy-Janthitrems in Epichloë Endophytes. Microorganisms. 2019; 7 (11):560.

Chicago/Turabian Style

Emma J. Ludlow; Simone Vassiliadis; Piyumi N. Ekanayake; Inoka K. Hettiarachchige; Priyanka Reddy; Tim I. Sawbridge; Simone J. Rochfort; German C. Spangenberg; Kathryn M. Guthridge. 2019. "Analysis of the Indole Diterpene Gene Cluster for Biosynthesis of the Epoxy-Janthitrems in Epichloë Endophytes." Microorganisms 7, no. 11: 560.

Journal article
Published: 07 November 2019 in Toxins
Reads 0
Downloads 0

The rapid identification and quantitation of alkaloids produced by Epichloë endophyte-infected pasture grass is important for the agricultural industry. Beneficial alkaloids, such as peramine, provide the grass with enhanced insect protection. Conversely, ergovaline and lolitrem B can negatively impact livestock. Currently, a single validated method to measure these combined alkaloids in planta does not exist. Here, a simple two-step extraction method was developed for Epichloë-infected perennial ryegrass (Lolium perenne L.). Peramine, ergovaline and lolitrem B were quantified using liquid chromatography–mass spectrometry (LC–MS). Alkaloid linearity, limit of detection (LOD), limit of quantitation (LOQ), accuracy, precision, selectivity, recovery, matrix effect and robustness were all established. The validated method was applied to eight different ryegrass-endophyte symbiota. Robustness was established by comparing quantitation results across two additional instruments; a triple quadruple mass spectrometer (QQQ MS) and by fluorescence detection (FLD). Quantitation results were similar across all three instruments, indicating good reproducibility. LOQ values ranged from 0.8 ng/mL to 6 ng/mL, approximately one hundred times lower than those established by previous work using FLD (for ergovaline and lolitrem B), and LC–MS (for peramine). This work provides the first highly sensitive quantitative LC–MS method for the accurate and reproducible quantitation of important endophyte-derived alkaloids.

ACS Style

Simone Vassiliadis; Aaron C. Elkins; Priyanka Reddy; Kathryn M. Guthridge; German C. Spangenberg; Simone J. Rochfort. A Simple LC–MS Method for the Quantitation of Alkaloids in Endophyte-Infected Perennial Ryegrass. Toxins 2019, 11, 649 .

AMA Style

Simone Vassiliadis, Aaron C. Elkins, Priyanka Reddy, Kathryn M. Guthridge, German C. Spangenberg, Simone J. Rochfort. A Simple LC–MS Method for the Quantitation of Alkaloids in Endophyte-Infected Perennial Ryegrass. Toxins. 2019; 11 (11):649.

Chicago/Turabian Style

Simone Vassiliadis; Aaron C. Elkins; Priyanka Reddy; Kathryn M. Guthridge; German C. Spangenberg; Simone J. Rochfort. 2019. "A Simple LC–MS Method for the Quantitation of Alkaloids in Endophyte-Infected Perennial Ryegrass." Toxins 11, no. 11: 649.

Review
Published: 27 May 2019 in Toxins
Reads 0
Downloads 0

Indole-diterpenes are an important class of chemical compounds which can be unique to different fungal species. The highly complex lolitrem compounds are confined to Epichloë species, whilst penitrem production is confined to Penicillium spp. and Aspergillus spp. These fungal species are often present in association with pasture grasses, and the indole-diterpenes produced may cause toxicity in grazing animals. In this review, we highlight the unique structural variations of indole-diterpenes that are characterised into subgroups, including paspaline, paxilline, shearinines, paspalitrems, terpendoles, penitrems, lolitrems, janthitrems, and sulpinines. A detailed description of the unique biological activities has been documented where even structurally related compounds have displayed unique biological activities. Indole-diterpene production has been reported in two classes of ascomycete fungi, namely Eurotiomycetes (e.g., Aspergillus and Penicillium) and Sordariomycetes (e.g., Claviceps and Epichloë). These compounds all have a common structural core comprised of a cyclic diterpene skeleton derived from geranylgeranyl diphosphate (GGPP) and an indole moiety derived from tryptophan. Structure diversity is generated from the enzymatic conversion of different sites on the basic indole-diterpene structure. This review highlights the wide-ranging biological versatility presented by the indole-diterpene group of compounds and their role in an agricultural and pharmaceutical setting.

ACS Style

Priyanka Reddy; Kathryn Guthridge; Simone Vassiliadis; Joanne Hemsworth; Inoka Hettiarachchige; German Spangenberg; Simone Rochfort. Tremorgenic Mycotoxins: Structure Diversity and Biological Activity. Toxins 2019, 11, 302 .

AMA Style

Priyanka Reddy, Kathryn Guthridge, Simone Vassiliadis, Joanne Hemsworth, Inoka Hettiarachchige, German Spangenberg, Simone Rochfort. Tremorgenic Mycotoxins: Structure Diversity and Biological Activity. Toxins. 2019; 11 (5):302.

Chicago/Turabian Style

Priyanka Reddy; Kathryn Guthridge; Simone Vassiliadis; Joanne Hemsworth; Inoka Hettiarachchige; German Spangenberg; Simone Rochfort. 2019. "Tremorgenic Mycotoxins: Structure Diversity and Biological Activity." Toxins 11, no. 5: 302.

Journal article
Published: 03 January 2019 in Toxins
Reads 0
Downloads 0

The most potent of the indole diterpenes, lolitrem B, is found in perennial ryegrass (Lolium perenne L.) infected with the endophyte Epichloë festucae var. lolii (also termed LpTG-1). Ingestion causes a neurological syndrome in grazing livestock called ryegrass staggers disease. To enable the rapid development of new forage varieties, the toxicity of lolitrem B and its biosynthetic intermediates needs to be established. However, most of these indole diterpenes are not commercially available; thus, isolation of these compounds is paramount. A concentrated endophyte-infected perennial ryegrass seed extract was subjected to silica flash chromatography followed by preparative HPLC and purification by crystallization resulting in lolitrem B and the intermediate compounds lolitrem E, paspaline and terpendole B. The four-step isolation and purification method resulted in a 25% yield of lolitrem B. After isolation, lolitrem B readily degraded to its biosynthetic intermediate, lolitriol. We also found that lolitrem B can readily degrade depending on the solvent and storage conditions. The facile method which takes into consideration the associated instability of lolitrem B, led to the purification of indole diterpenes in quantities sufficient for use as analytical standards for identification in pastures, and/or for toxicity testing in pasture development programs.

ACS Style

Priyanka Reddy; Myrna A. Deseo; Vilnis Ezernieks; Kathryn Guthridge; German Spangenberg; Simone Rochfort. Toxic Indole Diterpenes from Endophyte-Infected Perennial Ryegrass Lolium perenne L.: Isolation and Stability. Toxins 2019, 11, 16 .

AMA Style

Priyanka Reddy, Myrna A. Deseo, Vilnis Ezernieks, Kathryn Guthridge, German Spangenberg, Simone Rochfort. Toxic Indole Diterpenes from Endophyte-Infected Perennial Ryegrass Lolium perenne L.: Isolation and Stability. Toxins. 2019; 11 (1):16.

Chicago/Turabian Style

Priyanka Reddy; Myrna A. Deseo; Vilnis Ezernieks; Kathryn Guthridge; German Spangenberg; Simone Rochfort. 2019. "Toxic Indole Diterpenes from Endophyte-Infected Perennial Ryegrass Lolium perenne L.: Isolation and Stability." Toxins 11, no. 1: 16.

Original article
Published: 15 November 2018 in Molecular Genetics and Genomics
Reads 0
Downloads 0

Development of grass–endophyte associations with minimal or no detrimental effects in combination with beneficial characteristics is important for pastoral agriculture. The feasibility of enhancing production of an endophyte-derived beneficial alkaloid through introduction of an additional gene copy was assessed in a proof-of-concept study. Sexual and asexual Epichloë species that form symbiotic associations with cool-season grasses of the Poaceae sub-family Pooideae produce bioactive alkaloids that confer resistance to herbivory by a number of organisms. Of these, peramine is thought to be crucial for protection of perennial ryegrass (Lolium perenne L.) from the Argentinian stem weevil, an economically important exotic pest in New Zealand, contributing significantly to pasture persistence. A single gene (perA) has been identified as solely responsible for peramine biosynthesis and is distributed widely across Epichloë taxa. In the present study, a functional copy of the perA gene was introduced into three recipient endophyte genomes by Agrobacterium tumefaciens-mediated transformation. The target strains included some that do not produce peramine, and others containing different perA gene copies. Mitotically stable transformants generated from all three endophyte strains were able to produce peramine in culture and in planta at variable levels. In summary, this study provides an insight into the potential for artificial combinations of alkaloid biosynthesis in a single endophyte strain through transgenesis, as well as the possibility of using novel genome editing techniques to edit the perA gene of non-peramine producing strains.

ACS Style

Inoka K. Hettiarachchige; Aaron C. Elkins; Priyanka Reddy; Ross C. Mann; Kathryn M. Guthridge; Timothy I. Sawbridge; John W. Forster; German C. Spangenberg. Genetic modification of asexual Epichloë endophytes with the perA gene for peramine biosynthesis. Molecular Genetics and Genomics 2018, 294, 315 -328.

AMA Style

Inoka K. Hettiarachchige, Aaron C. Elkins, Priyanka Reddy, Ross C. Mann, Kathryn M. Guthridge, Timothy I. Sawbridge, John W. Forster, German C. Spangenberg. Genetic modification of asexual Epichloë endophytes with the perA gene for peramine biosynthesis. Molecular Genetics and Genomics. 2018; 294 (2):315-328.

Chicago/Turabian Style

Inoka K. Hettiarachchige; Aaron C. Elkins; Priyanka Reddy; Ross C. Mann; Kathryn M. Guthridge; Timothy I. Sawbridge; John W. Forster; German C. Spangenberg. 2018. "Genetic modification of asexual Epichloë endophytes with the perA gene for peramine biosynthesis." Molecular Genetics and Genomics 294, no. 2: 315-328.