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Does The Genomic Landscape Of Species Divergence In Phaseolus Beans Coerce Parallel Signatures Of Adaptation And Domestication?, Andrés J. Cortés, Paola Skeen, Matthew W. Blair, María I. Chacón-Sánchez

Agricultural and Environmental Sciences Faculty Research

Exploring the genomic architecture of species and populations divergence aids understanding how lineages evolve and adapt, and ultimately can show the repeatability of evolutionary processes. Yet, the genomic signatures associated with divergence are still relatively unexplored, leading to a knowledge gap on whether species divergence ultimately differs in its genetic architecture from divergence at other spatial scales (i.e., populations, ecotypes). Our goal in this research was to determine whether genomic islands of speciation are more prone to harbor within-species differentiation due to genomic features, suppressed recombination, smaller effective population size or increased drift, across repeated hierarchically nested levels of divergence. …

Biochemical, Physiological And Phenological Genetic Analysis In Common Bean (Phaseolus Vulgaris L.) Under Salt Stress, Yacine Torche, Matthew Blair, Chougui Saida

Agricultural and Environmental Sciences Faculty Research

Salinity is one of the most important abiotic stresses affecting agricultural productivity. The present study investigated combining abilities, heterosis and heritability estimates of common bean under salinity conditions for biochemical, physiological and phenological traits using a half-diallel cross. The salinity stress treatments were applied during all the vegetative cycle. Genetic analysis revealed highly significant genotypic variations between the four parents and their six hybrids, indicating a genetic variability and possibility of genetic improvement using such genetic material of common bean for salinity tolerance. Both general (GCA) and specific (SCA) combining abilities were highly significant for all the studied traits under …

Morphological Assessment Of Cultivated And Wild Amaranth Species Diversity, Ranjita Thapa, Matthew W. Blair

Agricultural and Environmental Sciences Faculty Research

Amaranthus L. is genus of C4 dicotyledonous herbaceous plants comprising approximately 70 species, with three subgenera, which contains both cultivated and wild types, where cultivated ones are used for food grains, leafy vegetables, potential forages and ornamentals. Grain amaranth are pseudocereals from three species domesticated in North and South America and are notable for containing high amount of protein and minerals and balanced amino acid in their small seeds. Genetic diversity analysis of amaranths is important for development of core set of germplasm with widely diverse population and effective utilization of plant genetic resources. In this study, we evaluated a …

Evaluation Of Biological Agents For Control Of Macrophomina Root Rot And Powdery Mildew In Flowering Dogwood (Cornus Florida L.), Margaret T. Mmbaga, Lucas M. Mackasmiel, Frank A. Mrema

Agricultural and Environmental Sciences Faculty Research

Six biological control agents (BCAs) (two bacteria, two fungi, and two yeasts) that were previously shown to be effective against powdery mildew (Erysiphe pulchra) were tested for efficacy against Macrophomina phaseolina root rot on flowering dogwood (Cornus florida) in the greenhouse. Two of the bacterial isolates, Stenotrophomonas sp. (B17A) and Serratia sp. (B17B), were effective in controlling both macrophomina root rot and powdery mildew, similar to fungicide control thiophanate methyl, when roots were drenched with the six BCAs individually. In addition, the two bacterial BCAs improved plant growth with respect to stem diameter, stem length, dry weight, and green foliage …

Weak Effects Of Biochar And Nitrogen Fertilization On Switchgrass Photosynthesis, Biomass, And Soil Respiration, Dafeng Hui, Chih-Li Yu, Qi Deng, Priya Saini, Kenya Collins, Jason De Koff

Agricultural and Environmental Sciences Faculty Research

Application of nitrogen (N) fertilizer plus biochar may increase crop yield, but how biochar will interact with N fertilization to affect bioenergy crop switchgrass physiology, biomass, and soil CO₂ emission (i.e., soil respiration) from switchgrass fields remains unclear. Here, we assessed this issue by conducting a field experiment near Nashville TN with two levels of biochar treatment (a control without biochar addition and biochar addition of 9 Mg ha⁻¹), and four N fertilization levels (0 kg N ha⁻¹, 17 kg N ha⁻¹, 34 kg N ha⁻¹, and 67 kg N ha …

Evaluation Of A Lignin-Encapsulated Nootkatone Formulation Against Tetranychus Urticae (Acari: Tetranychidae), Karla M. Addesso, Paul A. O'Neal, Shannen Leahy, Kevin Trostel, Robert W. Behle

Agricultural and Environmental Sciences Faculty Research

Botanical-based miticides, such as neem oil, are used in organic and conventional agronomic production as part of chemical rotation plans to suppress pest mite populations. Other plant-based compounds such as nootkatone (a component of essential oils distilled from grapefruit, Citrus paradisi Macfayden (Rutaceae), and Alaskan yellow cedar, Chamaecyparis nootkatensis [D. Don] Spach [Cupressaceae]), also may serve as effective organic miticides in crop production systems. We report on a lignin-encapsulated (LE) nootkatone formulation (previously effective at repelling ticks) that was evaluated as a miticide against the twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). At an application rate of 1 g/L …

Electrical Conductivity Of Nutrient Solution Influenced Photosynthesis, Quality, And Antioxidant Enzyme Activity Of Pakchoi (Brassica Campestris L. Ssp. Chinensis) In A Hydroponic System, Xiaotao Ding, Yuping Jiang, Hong Zhao, Doudou Guo, Lizhong He, Fuguang Liu, Qiang Zhou, Dilip Nandwani, Dafeng Hui, Jizhu Yu

Agricultural and Environmental Sciences Faculty Research

To find an electrical conductivity (EC) in the nutrient solution used for pakchoi (Brassica campestris L. ssp. Chinensis) cultivation that optimizes the plant’s physiology, growth, and quality, we conducted an experiment with eight EC treatments (from EC0 to EC9.6) in a hydroponic production system (i.e. soilless culture) under greenhouse condition in Shanghai, China. Plants biomass production, leaf photosynthesis, vegetable quality variables, tissue nitrate and nitrite contents, and antioxidant enzyme activities were measured. The results showed that very high (EC9.6) or low EC (EC0-0.6) treatments clearly decreased plants fresh weight (FW) and dry weight (DW), leaf size, leaf water content, leaf …

Interaction Of A Preventative Fungicide Treatment And Root Rot Pathogen On Ambrosia Beetle Attacks During A Simulated Flood Event, Karla Addesso, Fulya Baysal-Gurel, Jason Oliver, Christopher Ranger, Paul O'Neal

Agricultural and Environmental Sciences Faculty Research

Flooding can increase tree susceptibility to root rot pathogens as well as attacks by ambrosia beetles attracted to stress-induced ethanol emissions. The objective of this study was to investigate the interaction of a preventative fungicide treatment and root infection with Phytophthora cinnamomi on ambrosia beetle attacks in flood stressed trees. A fungicide (Pageant® Intrinsic®) was evaluated in two flood trials using Eastern redbud and tulip poplar trees with treatments including the fungicide with or without pathogen or no fungicide with or without pathogen. Fungicide treated trees had fewer ambrosia beetle attacks, particularly in trees without P. cinnamomi co-infection. In a …

Swirski Mite Controlled-Release Sachets As A Pest Management Tool In Container Tree Production, Karla M. Addesso, Anthony L. Witcher, Donna C. Fare

Agricultural and Environmental Sciences Faculty Research

Adoption of biological control tools in woody ornamental nursery production has lagged behind other agriculture fields. One of the major obstacles to adoption is lack of information on the efficacy of various biological control agents in nursery production systems. The predatory mite Amblyseius swirskii, sold commercially as “swirski mite,” is a generalist predatory mite that has recently been adopted as a generalist control for a wide range of mite and insect pests, including thrips (Thripidae), whiteflies (Aleyrodidae), eriophyid mites (Eriophyidae), broad mite (Polyphagotarsonemus latus), and spider mites (Tetranychidae). A controlled-release sachet formulation of swirski mite was evaluated …

The Biochemical Composition And Transcriptome Of Cotyledons From Brassica Napus Lines Expressing The Atgl3 Transcription Factor And Exhibiting Reduced Flea Beetle Feeding, Margaret Gruber, Ushan Alahakoon, Ali Taheri, Nayidu Nagubushana, Rong Zhou, Banyar Aung, Andrew Sharpe, Abdelali Hannoufa, Peta Bonham-Smith, Dwayne D. Hegedus

Agricultural and Environmental Sciences Faculty Research

Background

Previously, transgenic trichome-bearing (hairy leaf) Brassica napus lines expressing either the Arabidopsis thaliana GL3 gene (line AtGL3+) [1] or the AtGL3 gene in combination with an RNAi construct to down-regulate TTG1 (line K-5-8) [2] were developed. The leaves of these lines exhibited altered insect feeding (flea beetle) and oviposition (diamondback moth) behaviour compared to the non-transgenic semi-glabrous leaves of B. napus cv. Westar. Interestingly, the cotyledons of these lines remained glabrous, but also showed reduced feeding by flea beetles. Here we examine the composition and global transcriptome of the glabrous cotyledons from these transgenic lines …

Differential Effects Of Warming And Nitrogen Fertilization On Soil Respiration And Microbial Dynamics In Switchgrass Croplands, Jianwei Li, Siyang Jian, Jason P. De Koff, Chad S. Lane, Gangsheng Wang, Melanie A. Mayes, Dafeng Hui

Agricultural and Environmental Sciences Faculty Research

The mechanistic understanding of warming and nitrogen (N) fertilization, alone or in combination, on microbially mediated decomposition is limited. In this study, soil samples were collected from previously harvested switchgrass (Panicum virgatum L.) plots that had been treated with high N fertilizer (HN: 67 kg N ha−1) and those that had received no N fertilizer (NN) over a 3-year period. The samples were incubated for 180 days at 15 °C and 20 °C, during which heterotrophic respiration, δ13C of CO2, microbial biomass (MB), specific soil respiration rate (Rs: respiration per unit of microbial biomass), and exoenzyme activities were …

‘Sunglow’ American Witchhazel, Lisa W. Alexander, Anthony Witcher, Michael A. Arnold

Agricultural and Environmental Sciences Faculty Research

Witchhazel (Hamamelis sp.) cultivars are now available in an array of forms and flower colors, including several native, pollinator-friendly cultivars. However, little is known about response of witchhazel cultivars to powdery mildew (Podosphaera biuncinata) or the growth and flowering characteristics of witchhazel cultivars in a nursery field production setting. To provide growth, flowering, and disease incidence data to nursery growers, a cultivar trial including 23 cultivars of witchhazel representing five species was planted Apr. 2016 in McMinnville, TN. Plant growth, flowering density, length of bloom, and foliar disease incidence were evaluated over three growing seasons between May 2016 and Oct. …

Development And Phenotypic Screening Of An Ethyl Methane Sulfonate Mutant Population In Soybean, Mary J. Espina, C. M. Sabbir Ahmed, Angelina Bernardini, Ekundayo Adeleke, Zeinab Yadegari, Prakash Arelli, Vince Pantalone, Ali Taheri

Agricultural and Environmental Sciences Faculty Research

Soybean is an important oil-producing crop in the Fabaceae family and there are increasing demands for soybean oil and other soybean products. Genetic improvement of soybean is needed to increase its production. In order to provide genetic diversity and resources for identifying important genes, a new ethyl methane sulfonate (EMS) mutagenized soybean population was generated using the newly released germplasm, JTN-5203 (maturity group V). Treatment of soybean seeds with 60 mM EMS concentration was found to be suitable for inducing mutation. A total of 1,820 M1 individuals were produced from 15,000 treated seeds. The resulting M2 population was planted in …

Uneven Recombination Rate And Linkage Disequilibrium Across A Reference Snp Map For Common Bean (Phaseolus Vulgaris L.), Matthew W. Blair, Andrés J. Cortés, Andrew D. Farmer, Wei Huang, Daniel Ambachew, R. Varma Penmetsa, Noelia Carrasquilla-Garcia, Teshale Assefa, Steven B. Cannon

Agricultural and Environmental Sciences Faculty Research

Recombination (R) rate and linkage disequilibrium (LD) analyses are the basis for plant breeding. These vary by breeding system, by generation of inbreeding or outcrossing and by region in the chromosome. Common bean (Phaseolus vulgaris L.) is a favored food legume with a small sequenced genome (514 Mb) and n = 11 chromosomes. The goal of this study was to describe R and LD in the common bean genome using a 768-marker array of single nucleotide polymorphisms (SNP) based on Trans-legume Orthologous Group (TOG) genes along with an advanced-generation Recombinant Inbred Line reference mapping population (BAT93 x Jalo EEP558) …

Flowering Dogwood Infections With Macrophomina Phaseolina, Margaret T. Mmbaga, Lucas A. Mackasmiel, Frank A. Mrema

Agricultural and Environmental Sciences Faculty Research

Macrophomina phaseolina was isolated from the crown region and roots of mature flowering dogwood (Cornus florida L.) trees in the landscape and nursery plantings. Although this pathogen has been reported in Cornus species, its occurrence and impact on C. florida has not been reported. Pathogenicity tests were conducted on dogwood seedlings, and all inoculated seedlings developed root necrotic lesions and no small lateral roots, whereas the non-inoculated control seedlings remained disease-free and developed numerous small roots. Seedlings inoculated with M. phaseolina exhibited numerous microsclerotia, but non-inoculated seedlings did not. In greenhouse experiments, plants inoculated on the stems near the soil …

Genotyping By Sequencing And Genome–Environment Associations In Wild Common Bean Predict Widespread Divergent Adaptation To Drought, Andrés J. Cortés, Matthew W. Blair

Agricultural and Environmental Sciences Faculty Research

Drought will reduce global crop production by >10% in 2050 substantially worsening global malnutrition. Breeding for resistance to drought will require accessing crop genetic diversity found in the wild accessions from the driest high stress ecosystems. Genome–environment associations (GEA) in crop wild relatives reveal natural adaptation, and therefore can be used to identify adaptive variation. We explored this approach in the food crop Phaseolus vulgaris L., characterizing 86 geo-referenced wild accessions using genotyping by sequencing (GBS) to discover single nucleotide polymorphisms (SNPs). The wild beans represented Mesoamerica, Guatemala, Colombia, Ecuador/Northern Peru and Andean groupings. We found high polymorphism with a …

Effects Of Precipitation Changes On Switchgrass Photosynthesis, Growth, And Biomass: A Mesocosm Experiment, Dafeng Hui, Chih-Li Yu, Qi Deng, E. Kudjo Dzantor, Suping Zhou, Sam Dennis, Roger Sauve, Terrance L. Johnson, Philip A. Fay, Weijun Shen, Yiqi Luo

Agricultural and Environmental Sciences Faculty Research

Climate changes, including chronic changes in precipitation amounts, will influence plant physiology and growth. However, such precipitation effects on switchgrass, a major bioenergy crop, have not been well investigated. We conducted a two-year precipitation simulation experiment using large pots (95 L) in an environmentally controlled greenhouse in Nashville, TN. Five precipitation treatments (ambient precipitation, and -50%, -33%, +33%, and +50% of ambient) were applied in a randomized complete block design with lowland "Alamo" switchgrass plants one year after they were established from tillers. The growing season progression of leaf physiology, tiller number, height, and aboveground biomass were determined each growing …

Nitrogen Fertilization Elevated Spatial Heterogeneity Of Soil Microbial Biomass Carbon And Nitrogen In Switchgrass And Gamagrass Croplands, Jianwei Li, Chunlan Guo, Siyang Jian, Qi Deng, Chih-Li Yu, Kudjo E. Dzantor, Dafeng Hui

Agricultural and Environmental Sciences Faculty Research

The effects of intensive nitrogen (N) fertilizations on spatial distributions of soil microbes in bioenergy croplands remain unknown. To quantify N fertilization effect on spatial heterogeneity of soil microbial biomass carbon (MBC) and N (MBN), we sampled top mineral horizon soils (0-15 cm) using a spatially explicit design within two 15-m2 plots under three fertilization treatments in two bioenergy croplands in a three-year long fertilization experiment in Middle Tennessee, USA. The three fertilization treatments were no N input (NN), low N input (LN: 84 kg N ha−1 in urea) and high N input (HN: 168 kg N ha−1 in urea). …

Warming Deferentially Altered Multidimensional Soil Legacy Induced By Past Land Use History, Weiling Dong, Alin Song, Xueduan Liu, Bing Yu, Boren Wang, Yuqiu Lu, Yanling Li, Huaqun Yin, Jianwei Li, Fenliang Fan

Agricultural and Environmental Sciences Faculty Research

The legacy effects of previous land use and climate history may affect current soil function. However, the manner in which these legacy effects of land use are modulated by the subsequent climate remains unclear. For this reason, we investigated how the legacies of soil multiple functions left by conversion of grassland to agricultural management were mediated by climate warming with a reciprocal transplant approach. The overall legacy was further separated into the contributions by changes in the abiotic properties of the soil (abiotic process) and microbial community (biotic process). We here hypothesized that warming may mediate the legacy effects of …

Bacterial Spot And Blight Diseases Of Ornamental Plants Caused By Different Xanthomonas Species In Turkey, Mustafa Mirik, Yesim Aysan, Fulya Baysal-Gurel

Agricultural and Environmental Sciences Faculty Research

Putative strains belonging to Xanthomonas spp. causing leaf spot and blight diseases on geranium (Pelargonium peltatum and P. hortorum), begonia (Begonia × tuberhybrida), anthurium (Anthurium andraeanum), Chinese hibiscus (Hibiscus rosa-sinensis), and English ivy (Hedera helix) growing in Turkey were isolated. All bacterial strains were classified as Gram-negative, oxidase negative, catalase, levan and starch hydrolysis positive, with hypersensitive reaction positive on tobacco and pathogenic to host plants. Identification of these strains was further confirmed by serological method using ELISA kits, conventional PCR, carbon utilisation, and FAME. Results of the identification showed that 28, 24, 10, 2, and 1 strains were identified …