Entomology and Plant Pathology Department, NC State
Thomas Hall 2572A
We are interested in the genetic and mechanistic bases of natural variation in quantitative disease resistance and the defense response in maize. Quantitative disease resistance, also known as partial disease resistance, confers a level of resistance that is less than complete but is usually effective in protecting yield.
We’re interested in identifying the associated loci ( the quantitative trait loci), the underlying genes and figuring out how they work.
Area(s) of Expertise
Maize, Disease Resistance, Defense Response, Genetics
- Analysis of the transcriptomic, metabolomic, and gene regulatory responses to Puccinia sorghi in maize , MOLECULAR PLANT PATHOLOGY (2021)
- Development and Use of a Seedling Growth Retardation Assay to Quantify and Map Loci Underlying Variation in the Maize Basal Defense Response , PhytoFrontiers™ (2021)
- Maize Plants Chimeric for an Autoactive Resistance Gene Display a Cell-Autonomous Hypersensitive Response but Non-Cell Autonomous Defense Signaling , MOLECULAR PLANT-MICROBE INTERACTIONS (2021)
- Maize metacaspases modulate the defense response mediated by the NLR protein Rp1‐D21 likely by affecting its subcellular localization , The Plant Journal (2021)
- Microbe-dependent heterosis in maize , PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA (2021)
- Multi-Omics Analyses Reveal the Regulatory Network and the Function of ZmUGTs in Maize Defense Response , FRONTIERS IN PLANT SCIENCE (2021)
- The maize E3 ligase ZmCER9 specifically targets activated NLRs for degradation , (2021)
- The maize ZmMIEL1 E3 ligase and ZmMYB83 transcription factor proteins interact and regulate the hypersensitive defence response , MOLECULAR PLANT PATHOLOGY (2021)
- Variation in Gene Expression between Two Sorghum bicolor Lines Differing in Innate Immunity Response , PLANTS-BASEL (2021)
- A CRISPR/dCas9 toolkit for functional analysis of maize genes , PLANT METHODS (2020)
In maize and many other plants, F1 hybrids perform better than their inbred parent lines - a phenomenon known as heterosis. The causes of heterosis have been investigated for over a century but are still poorly understood. Our preliminary data suggest a novel mechanism, not previously reported, in which growth in sterile conditions reduces or eliminates heterosis for root size- a pattern that we term Microbe-Dependent Heterosis (MDH). The causes of MDH are unclear; potential explanations include (1) superior resistance of hybrids to weakly pathogenic soil biota, or (2) immune over-reactions by inbred maize in response to innocuous soil biota. The proposed experiments will help to distinguish between these possibilities by exploring the genetic, ecological, and molecular causes of MDH. First, we will test a wide range of individual microbial strains as well as naturally-occurring soil biota for the ability to induce MDH. Second, we will map the genetic architecture of MDH to identify genomic loci whose effect on heterosis is dependent on the microbial environment, and test for a genetic correlation with loci underlying resistance to a variety of pathogenic microbes in the field. Third, we will investigate the molecular mechanisms of MDH by measuring gene and protein expression of both hybrid and inbred plants as well as the microbes inside their roots. The results of these experiments will clarify the microbial features and patterns of plant immune activity that result in MDH.
The purpose of this project is to develop a handheld Mueller matrix polarimeter that can be deployed to measure leaves in transmission. Leaves from different corn varieties will be quantified using both this handheld unit and our laboratory unit (an imaging Mueller Matrix polarimeter). These data will be compared to ground truth from e.g., enzymatic, colorimetric, 1D-NMR, and Mass-spectrometry based analyses, to correlate polarimetry measurements to metabolic concentration. Additionally, we will investigate polarization in reflection using a hyperspectral imaging polarimeter to quantify polarizationâ€™s ability to correct for bidirectional reflectance effects from canopy level measurements.
More than a third of crop yields are currently lost due to abiotic and biotic stressors such as drought, pests, and disease. These stressors are expected to worsen in a warmer, drier future, resulting in crop yields further declining ~25%; however, breeding is only expected to rescue 7-15% of that loss . The plant microbiome is a new avenue of plant management that may help fill this gap. All plants have fungi living inside their leaves (â€œfoliar fungal endophytesâ€). This is an ancient and intimate relationship in which the fungi affect plant physiology, biotic and abiotic stress tolerance, and productivity. For example, some foliar fungi prevent or delay onset of major yield-limiting diseases caused by pathogens such as Fusarium head blight . Foliar endophytes also reduce plant water loss by up to half and delay wilting by several weeks [3, 4]. Endophyte effects on plants occur via diverse genes and metabolites, including genes involved in stress responses and plant defense . Genes and metabolites also predict how interactions in fungal consortia affect host stress responses, which is important for developing field inoculations . Because newly emergent leaves lack fungi, endophytes are also an attractive target for manipulation (particularly compared to soils, where competition with the existing microbial community inhibits microbial additives). We propose to address the role of endophytic â€œmycobiomesâ€ in stress tolerance of five North Carolina food, fiber, and fuel crops (corn, hemp, soybean, switchgrass, wheat), and to develop tools that can push this field beyond its current limits. Our major objectives (Fig. 1) are to: 1. Identify key microbiome scales to optimally manage endophytes 2. Determine fungal mechanisms via greenhouse tests, modeling, and genetic engineering 3. Build tools for field detection of endophytes 4. Understand the regulatory environment and engage diverse stakeholders Results of these objectives will allow us to make significant progress in both understanding the basic biology of plant-fungal interactions and managing those interactions in real-world settings. Our extension efforts will also bring these ideas to the broader community. Finally, we will also be well positioned to pursue several future research endeavors supported by federal granting agencies.
We generally assess levels of foliar disease in corn by observation in the field using a visual scale. While this method is robust and gives reproducible data, it does not provide qualitative data such as lesion size or shape, nor does it give us good data on speed of disease progression or on timing of initial symptoms. We will rate a set of 50 genetically similar lines each of which has a different allele conferring resistance to the foliar disease southern leaf blight. We will use a variety of approaches to rate disease , including hyperspectral imaging and digital imaging. We will also rate them conventionally at very frequent intervals. Finally, we will measure yield. This work will help to develop methods for the early detection of foliar disease in the field. It will also characterize disease progression and the relationship between symptoms and yield loss. This knowledge will aid in the development of predictive models to guide farmers in the decision of whether and when to apply fungicides. The characterization of different mechanisms used by different resistance genes will guide breeders in the combination of resistance genes to produce more optimally-robust disease resistant lines.
Arbuscular mycorrhiza (AM) are soil-borne fungi that form intimate symbiotic associations with the roots of most land plants. AM fungi act as extensions of the root system, increasing the root â€œuptake areaâ€ more than 1000-fold and considerably improving the plant's ability to acquire water and nutrients from the soil. AM fungi therefore substantially improve the host plantâ€™s access to macronutrients including phosphorous (P), potassium (K) and nitrogen (N), and micronutrients. This proposal describes a project to understand the genetics controlling the association between corn and AM fungi. If successful, this will facilitate the increased used of AM fungi in corn cultivation and help reduce the expensive and ecologically-damaging use of fertilizers.