Carolyn Young
Department Head
Professor
Varsity Research Building, Module 6, Suite 1535
Bio
Dr. Carolyn Young was a Professor at the Noble Research Institute, in Ardmore, Oklahoma for 15 years and spent 6 months as Principal Scientist at Nature’s Fynd in Bozeman Montana. She is internationally recognized for research on seed transmitted fungal endophytes and their impact on forage grazing systems, endophyte diversity in native grasses and crop wild relatives, pecan scab and a root rot pathogen of alfalfa. She has discovered genes for the synthesis of bioprotective alkaloids, identified and described new endophyte species, and developed genomic and culture resources. She established educational activities centered on the inconspicuous symbiosis and provided knowledge and tools to stakeholders. Carolyn is originally from New Zealand, where she completed her studies at Massey University in Palmerston North. She moved to the USA in 2004 for a postdoctoral fellowship with Dr. Sophien Kamoun at the OARDC, Ohio State University. In 2006 she started her research lab at the Noble Research Institute. Carolyn has two sons who are now embarking on their own tertiary education journey. She was the founding Editor-in-Chief for the Phytobiomes Journal, which was established in 2017 by the American Phytopathological Society. Carolyn is passionate about mentoring and providing professional socialization and personal support to enhance early career development. She values the relationships with her mentors who have enriched her career, and as a result, she strives to pay forward similar experiences to others.
Diversity Matters: Endophytes and pathogens that impact agriculture
Sustainable plant productivity is greatly influenced by biotic and abiotic stresses that result in ongoing economic losses for stakeholders. My lab has addressed these problems by: (1) overcoming plant stress responses with beneficial endophytes that improve host persistence and (2) by understanding the biology of important regional pathogens to manage disease. I work on diverse plant associated fungal systems but link them by exploring fungal diversity (e.g. bioactive alkaloids, pathogenicity factors) at a population level and understanding their life-history strategies.
The success and resilience of cool-season forage grasses (e.g. tall fescue and perennial ryegrass) is attributed to a fungal seedborne symbiont from the genus Epichloë, which is a dominant and stable member of the grass microbiome. Epichloë species represent a dynamic group of endophytes that systemically infect above ground host tissue and vary in transmission strategies (horizontal, vertical or both), reproduction (sexual or asexual), and genome content (nonhybrid or hybrid). These endophytes are capable of producing a range of alkaloids that can protect the host from herbivory, but some alkaloids reduce livestock quality. Considerable genotypic and chemotypic diversity exist within the symbiont alkaloid biosynthetic pathways. We have shown through genome sequencing and genotyping that significant symbiont variation exists within a host and between host populations. Erosion from the chromosome end has provided natural diversity of indole-diterpenes produced by Epichloë species.
In contrast to these beneficial symbionts, fungal pathogen life-history strategies of Venturia effusa, causative agent of pecan scab, and the root pathogen Phymatotrichopsis omnivora are poorly understood. V. effusa is widely distributed across the southeastern USA and is treated as an asexual pathogen by pecan growers. We have recently shown that V. effusa is sexually active, with mating type idiomorphs in equilibrium in pecan orchards. Recent genome sequencing has helped elucidate the similarity between Venturia found on Carya illinoinensis (pecan) and other Carya species (hickory), and possible gene flow that may occur between the taxa. P. omnivora is considered a natural born killer of dicotyledonous plants, including cotton, pecan and Medicago sativa (alfalfa/lucerne). This pathogen is endemic to southwestern USA and dramatically reduces alfalfa stand productivity, with no known mechanisms of resistance. Aerial imaging has been used to identify areas of stand loss, follow disease progression, and determine the cost of production losses caused by P. omnivora. Recent genome sequencing of P. omnivora revealed the presence of a heterothallic mating type system but spatial distance between distinct isolates within a field would likely limit the existence of the sexual stage. Understanding genetic diversity within and between populations has provided insight into these diverse fungi-host systems that will help with development of management tools to maintain plant productivity.
Education
B.S. Massey University, New Zealand 1993
M.S. Genetics Massey University, New Zealand 1999
Ph.D. Molecular Biology Massey University, New Zealand 2005
Publications
- Transcriptome profile of pecan scab resistant and susceptible trees from a pecan provenance collection , BMC GENOMICS (2024)
- Fescue Toxicosis: Understanding the Fungal Cause and the Fungal Solution , JOURNAL OF ANIMAL SCIENCE (2023)
- Cross-species transcriptomics identifies core regulatory changes differentiating the asymptomatic asexual and virulent sexual life cycles of grass-symbiotic Epichloë fungi , G3 (2022)
- Population Genetic Characteristics and Mating Type Frequency of Venturia effusa from Pecan in South America , Phytopathology® (2022)
- Telomere-to-Telomere Genome Sequences across a Single Genus Reveal Highly Variable Chromosome Rearrangement Rates but Absolute Stasis of Chromosome Number , Journal of Fungi (2022)
- Mating Type Idiomorphs, Heterothallism, and High Genetic Diversity in Venturia carpophila, Cause of Peach Scab , Phytopathology® (2021)
- The First Genomic Resources for Phymatotrichopsis omnivora, a Soilborne Pezizomycete Pathogen with a Broad Host Range , Phytopathology® (2021)
- Chromosome-Level Reference Genome of Venturia effusa, Causative Agent of Pecan Scab , Molecular Plant-Microbe Interactions® (2020)
- Correction: Krauss, J., et al. Epichloë Endophyte Infection Rates and Alkaloid Content in Commercially Available Grass Seed Mixtures in Europe. Microorganisms 2020, 8, 498 , Microorganisms (2020)
- Epichloë Endophyte Infection Rates and Alkaloid Content in Commercially Available Grass Seed Mixtures in Europe , Microorganisms (2020)
Grants
Tall fescue is a valuable forage grass widely distributed across the U.S. occupying approximately 35 million acres. Unfortunately, the presence of a seed transmitted endophyte results in poor animal performance with lower average daily gains due to the production of ergot alkaloids. New fescue cultivars have been developed with endophyte strains that are considered safe for livestock as the endophyte is unable to make ergot alkaloids. Pasture renovation with these new fescue varieties is the best way to overcome fescue toxicosis, yet producers are wary of the technology and wonder if the benefits will outweigh the risks and cost. This project will provide producers with insight into the endophyte status of their tall fescue pastures by screening for endophyte presence. We will determine the level of endophyte infection and the endophyte strain present in a variety of pastures. Pastures at the Butner Beef Cattle Field Laboratory that have been renovated from toxic tall fescue (KY31) into novel endophyte-infected fescue will be screened to evaluate the persistence of the novel endophyte and determine if toxic fescue is present in these pastures. Producers that provide samples will receive a report describing the results of their pastures. The combined data generated from multiple North Carolina farms will be used in forage field days and workshops to show persistence of the novel endophyte-infected cultivars.