Life Sciences Commons^™

Cover Crops And Fertilization Alter Nitrogen Loss In Organic And Conventional Conservation Agriculture Systems, Rebecca E. Shelton, Krista L. Jacobsen, Rebecca L. Mcculley

Horticulture Faculty Publications

Agroecosystem nitrogen (N) loss produces greenhouse gases, induces eutrophication, and is costly for farmers; therefore, conservation agricultural management practices aimed at reducing N loss are increasingly adopted. However, the ecosystem consequences of these practices have not been well-studied. We quantified N loss via leaching, NH₃ volatilization, N₂O emissions, and N retention in plant and soil pools of corn conservation agroecosystems in Kentucky, USA. Three systems were evaluated: (1) an unfertilized, organic system with cover crops hairy vetch (Vicia villosa), winter wheat (Triticum aestivum), or a mix of the two (bi-culture); (2) an organic …

Characterizing Nitrogen Loss And Greenhouse Gas Flux Across An Intensification Gradient In Diversified Vegetable Systems, Debendra Shrestha

Theses and Dissertations--Plant and Soil Sciences

The area of vegetable production is growing rapidly world-wide, as are efforts to increase production on existing lands in these labor- and input-intensive systems. Yet information on nutrient losses, greenhouse gas emissions, and input efficiency is lacking. Sustainable intensification of these systems requires knowing how to optimize nutrient and water inputs to improve yields while minimizing negative environmental consequences. This work characterizes soil nitrogen (N) dynamics, nitrate (NO₃¯) leaching, greenhouse gas emissions, and crop yield in five diversified vegetable systems spanning a gradient of intensification that is characterized by inputs, tillage and rotational fallow periods. The study systems …

Reciprocal Effect Of Parental Lines On The Physiological Potential And Seed Composition Of Corn Hybrid Seeds, Juliana F. Santos, Lynnette M. A. Dirk, A. Bruce Downie, Mauricio F. G. Sanches, Roberval D. Vieira

Horticulture Faculty Publications

Obtaining corn hybrid seeds (Zea mays L.) with high vigour depends on the parental lines and the direction of the cross, and this relates to seed desiccation tolerance and composition. This research studied reciprocal crosses between pairs of proprietary, elite parent lines (L1 and L5; L2 and L4) producing hybrid seeds with different qualities attempting to correlate vigour with seed composition, focusing on storage proteins, starch and soluble sugar amounts. Four corn hybrid seed lots produced from reciprocal crosses were compared (HS 15 with HS 51, and HS 24 with HS 42) by assessing germination, vigour, and seedling emergence …

Positioning Of The Scrambled Receptor Requires Udp-Glc:Sterol Glucosyltransferase 80b1 In Arabidopsis Roots, Victoria G. Pook, Meera Nair, Kookhui Ryu, James C. Arpin, John Schiefelbein, Kathrin Schrick, Seth Debolt

Horticulture Faculty Publications

The biological function of sterol glucosides (SGs), the most abundant sterol derivatives in higher plants, remains uncertain. In an effort to improve our understanding of these membrane lipids we examined phenotypes exhibited by the roots of Arabidopsis (Arabidopsis thaliana) lines carrying insertions in the UDP-Glc:sterol glucosyltransferase genes, UGT80A2 and UGT80B1. We show that although ugt80A2 mutants exhibit significantly lower levels of total SGs they are morphologically indistinguishable from wild-type plants. In contrast, the roots of ugt80B1 mutants are only deficient in stigmasteryl glucosides but exhibit a significant reduction in root hairs. Sub-cellular investigations reveal that the plasma membrane …

Invasion Dynamics Of The Exotic Liana Euonymus Fortunei (Turcz.) Hand.-Mazz. (Wintercreeper), Todd J. Rounsaville

Theses and Dissertations--Biology

Elevated atmospheric CO₂ has been implicated as a driver of increased liana abundance worldwide. Known as disturbance creators and beneficiaries, lianas possess the potential to significantly influence forest ecosystems. I investigated the early-invasion dynamics of Euonymus fortunei (wintercreeper), an evergreen liana that is invading forests in eastern North America, disrupting native plant communities and ecosystem functions.

Wintercreeper is widely cultivated as an ornamental groundcover, frequently invading natural areas via asexual stem growth. Invasion of remote natural areas is dependent upon seed transport and may occur less frequently. I examined the mechanisms of seed dormancy by conducting a ‘move-along’ experiment …

Evaluating Soil Physical And Chemical Properties Following Addition Of Non-Composted Spent Coffee And Tea For Athletic Fields, Shuang Zhou

Theses and Dissertations--Plant and Soil Sciences

Physical and chemical properties of non-composted spent coffee (CF) and tea (T) suggest they may have applications as soil amendments for improving poor soils. Studies were conducted to determine 1) the effect of amendments on grass growth and soil properties, 2) the effect of incorporation versus surface application of amendments on soil properties, and 3) the effect of amendment application frequency on grass growth and soil properties. In the first study, amendments were mixed with sand and planted to bermudagrass. Treatments included CF, T, and peat moss (PM) mixed with sand, and 100% sand as a control. In the second …

Apple Tree Responses To Deficit Irrigation Combined With Periodic Applications Of Particle Film Or Abscisic Acid, Khalid M. Al-Absi, Douglas D. Archbold

Horticulture Faculty Publications

The objective of this study was to determine if the application of two antitranspirant compounds would moderate water deficit stress effects on physiological responses of “Granny Smith”, “Royal Gala” and “Golden Delicious” apple (Malus domestica Borkh.) trees on MM106 rootstock that occur during deficit irrigation. Uniform trees were grown in pots under water supply regimes of 30%, 60%, and 80% depletion of available water (DAW) before irrigation to runoff and received applications of kaolin particle film (PF) or abscisic acid (ABA) at 0, 30 and 60 days. At 120 days, genotype and deficit irrigation affected nearly all leaf traits, …

Combined Effects Of Fertilizer, Irrigation, And Paclobutrazol On Yield And Fruit Quality Of Mango, Babul C. Sarker, Mohammad A. Rahim, Douglas D. Archbold

Horticulture Faculty Publications

Combinations of fertilizer rates, foliar N sprays, irrigation practices, and paclobutrazol were studied to determine how much they could alter and/or improve mango (Mangifera indica L.) growth, flowering, and yield. Two treatment combinations derived from several years of prior studies of individual practices were compared: one combination was comprised of the best (BT) individual practices from the prior studies and included three applications of fertilizer, a 4% KNO₃ spray application before flowering, paclobutrazol at 7.5 g/L, and weekly irrigation, and the other combination was comprised of the next best (NB) individual practices including two applications of the same …

Quantification Of Carbohydrates In Grape Tissues Using Capillary Zone Electrophoresis, Lu Zhao, Ann M. Chanon, Nabanita Chattopadhyay, Imed E. Dami, Joshua J. Blakeslee

Kentucky Tobacco Research and Development Center Faculty Publications

Soluble sugars play an important role in freezing tolerance in both herbaceous and woody plants, functioning in both the reduction of freezing-induced dehydration and the cryoprotection of cellular constituents. The quantification of soluble sugars in plant tissues is, therefore, essential in understanding freezing tolerance. While a number of analytical techniques and methods have been used to quantify sugars, most of these are expensive and time-consuming due to complex sample preparation procedures which require the derivatization of the carbohydrates being analyzed. Analysis of soluble sugars using capillary zone electrophoresis (CZE) under alkaline conditions with direct UV detection has previously been used …

The Hiv-1 Tat Protein Is Monomethylated At Lysine 71 By The Lysine Methyltransferase Kmt7, Ibraheem Ali, Holly Ramage, Daniela Boehm, Lynnette M. A. Dirk, Naoki Sakane, Kazuki Hanada, Sara Pagans, Katrin Kaehlcke, Katherine Aull, Leor Weinberger, Raymond Trievel, Martina Schnoelzer, Masafumi Kamada, Robert L. Houtz, Melanie Ott

Horticulture Faculty Publications

The HIV-1 transactivator protein Tat is a critical regulator of HIV transcription primarily enabling efficient elongation of viral transcripts. Its interactions with RNA and various host factors are regulated by ordered, transient post-translational modifications. Here, we report a novel Tat modification, monomethylation at lysine 71 (K71). We found that Lys-71 monomethylation (K71me) is catalyzed by KMT7, a methyltransferase that also targets lysine 51 (K51) in Tat. Using mass spectrometry, in vitro enzymology, and modification-specific antibodies, we found that KMT7 monomethylates both Lys-71 and Lys-51 in Tat. K71me is important for full Tat transactivation, as KMT7 knockdown impaired the transcriptional activity …

[14C] Glucose Cell Wall Incorporation Assay For The Estimation Of Cellulose Biosynthesis, Chad Brabham, Jozsef Stork, Seth Debolt

Horticulture Faculty Publications

Cellulose is synthesized by Cellulose Synthase A proteins at the plasma membrane using the substrate UDP glucose. Herein, we provide a detailed method for measuring the incorporation of radiolabeled glucose into the cellulose fraction of the cell wall. In this method Arabidopsis seedlings are treated for 2 h with a cellulose biosynthesis inhibitor in the presence of radiolabeled glucose, and are subsequently boiled in acetic-nitric acid to solubilize non-cellulosic material. The radiolabeled glucose detected in the insoluble fraction indicates the amount of cellulose synthesized during the experimental timeframe. The short-term nature of this method is a useful tool in determining …

Prospecting For Energy-Rich Renewable Raw Materials: Agave Leaf Case Study, Kendall R. Corbin, Caitlin S. Byrt, Stefan Bauer, Seth Debolt, Don Chambers, Joseph A. M. Holtum, Ghazwan Karem, Marilyn Henderson, Jelle Lahnstein, Cherie T. Beahan, Antony Bacic, Geoffrey B. Fincher, Natalie S. Betts, Rachel A. Burton

Horticulture Faculty Publications

Plant biomass from different species is heterogeneous, and this diversity in composition can be mined to identify materials of value to fuel and chemical industries. Agave produces high yields of energy-rich biomass, and the sugar-rich stem tissue has traditionally been used to make alcoholic beverages. Here, the compositions of Agave americana and Agave tequilana leaves are determined, particularly in the context of bioethanol production. Agave leaf cell wall polysaccharide content was characterized by linkage analysis, non-cellulosic polysaccharides such as pectins were observed by immuno-microscopy, and leaf juice composition was determined by liquid chromatography. Agave leaves are fruit-like--rich in moisture, …

Calmodulin Methyltransferase Is Required For Growth, Muscle Strength, Somatosensory Development And Brain Function, Sitvanit Haziza, Roberta Magnani, Dima Lan, Omer Keinan, Ann Saada, Eli Hershkovitz, Nurit Yanay, Yoram Cohen, Yoram Nevo, Robert L. Houtz, Val C. Sheffield, Hava Golan, Ruti Parvari

Horticulture Faculty Publications

Calmodulin lysine methyl transferase (CaM KMT) is ubiquitously expressed and highly conserved from plants to vertebrates. CaM is frequently trimethylated at Lys-115, however, the role of CaM methylation in vertebrates has not been studied. CaM KMT was found to be homozygously deleted in the 2P21 deletion syndrome that includes 4 genes. These patients present with cystinuria, severe intellectual disabilities, hypotonia, mitochondrial disease and facial dysmorphism. Two siblings with deletion of three of the genes included in the 2P21 deletion syndrome presented with cystinuria, hypotonia, a mild/moderate mental retardation and a respiratory chain complex IV deficiency. To be able to attribute …

Engineering Plant Biomass Lignin Content And Composition For Biofuels And Bioproducts, Cassie Marie Welker, Vimal Kumar Balasubramanian, Carloalberto Petti, Krishan Mohan Rai, Seth Debolt, Venugopal Mendu

Horticulture Faculty Publications

Lignin is an aromatic biopolymer involved in providing structural support to plant cell walls. Compared to the other cell wall polymers, i.e., cellulose and hemicelluloses, lignin has been considered a hindrance in cellulosic bioethanol production due to the complexity involved in its separation from other polymers of various biomass feedstocks. Nevertheless, lignin is a potential source of valuable aromatic chemical compounds and upgradable building blocks. Though the biosynthetic pathway of lignin has been elucidated in great detail, the random nature of the polymerization (free radical coupling) process poses challenges for its depolymerization into valuable bioproducts. The absence of specific …

Characterization Of Culturable Bacterial Endophytes And Their Capacity To Promote Plant Growth From Plants Grown Using Organic Or Conventional Practices, Ye Xia, Seth Debolt, Jamin Dreyer, Delia Scott, Mark A. Williams

Horticulture Faculty Publications

Plants have a diverse internal microbial biota that has been shown to have an important influence on a range of plant health attributes. Although these endophytes have been found to be widely occurring, few studies have correlated agricultural production practices with endophyte community structure and function. One agricultural system that focuses on preserving and enhancing soil microbial abundance and biodiversity is organic farming, and numerous studies have shown that organically managed system have increased microbial community characteristics. Herein, the diversity and specificity of culturable bacterial endophytes were evaluated in four vegetable crops: corn, tomato, melon, and pepper grown under organic …

Horticulturae — An International, Multidisciplinary, Open Access Journal, Douglas D. Archbold

Horticulture Faculty Publications

No abstract provided.

Identification Of Micrornas In Two Species Of Tomato, Solanum Lycopersicum And Solanum Habrochaites, By Deep Sequencing, Shan-Shan Fan, Qian-Nan Li, Guang-Jun Guo, Jian-Chang Gao, Xiao-Xuan Wang, Yan-Mei Guo, John C. Snyder, Yong-Chen Du

Horticulture Faculty Publications

MicroRNAs (miRNAs) are ~21 nucleotide (nt), endogenous RNAs that regulate gene expression in plants. Increasing evidence suggests that miRNAs play an important role in species-specific development in plants. However, the detailed miRNA profile divergence has not been performed among tomato species. In this study, the small RNA (sRNA) profiles of Solanum lycopersicum cultivar 9706 and Solanum habrochaites species PI 134417 were obtained by deep sequencing. Sixty-three known miRNA families were identified from these two species, of which 39 were common. Further miRNA profile comparison showed that 24 known non-conserved miRNA families were species-specific between these two tomato species. In addition, …

Conservation Agriculture In Kentucky: Investigating Nitrogen Loss And Dynamics In Corn Systems Following Wheat And Hairy Vetch Cover Crops, Rebecca Erin Shelton

Theses and Dissertations--Plant and Soil Sciences

Unintentional nitrogen (N) loss from agroecosystems produces greenhouse gases, induces eutrophication, and is costly for farmers; therefore, adoption of conservation agricultural management practices, such as no-till and cover cropping, has increased. This study assessed N loss via leaching, NH₃ volatilization, N₂O emissions, and N retention in plant and soil pools of corn conservation agroecosystems across a year. Three systems were evaluated: 1) an unfertilized organic system with cover crops Vicia villosa, Triticum aestivum, or a mix of the two; 2) an organic system with a Vicia cover crop employing three fertilization schemes (0 N, organic N, …

The Influence Of Production Practices, Tillage, And Endophytic Bacteria On Bell Pepper Productivity And Physiology Under Different Irrigation Regimes, Zheng Wang

Theses and Dissertations--Plant and Soil Sciences

To evaluate the strip tillage in organic bell pepper (Capsicum annuum L.) production as an integrated system for sustainable vegetable cropping two-years of field trials were conducted in 2011 and 2012. The field trials were conducted to determine the viability of strip tillage in conventional and organic bell pepper production systems by comparing plant growth, water status, and fruit yield to plastic mulch grown plants application under different irrigation regimes. The two-year field data demonstrated that organic pepper with strip tillage application was a viable combination that produced comparable yield to conventional plastic mulch system and utilized water more …

Experimental Approaches To Study Plant Cell Walls During Plant-Microbe Interactions, Ye Xia, Carloalberto Petti, Mark A. Williams, Seth Debolt

Horticulture Faculty Publications

Plant cell walls provide physical strength, regulate the passage of bio-molecules, and act as the first barrier of defense against biotic and abiotic stress. In addition to providing structural integrity, plant cell walls serve an important function in connecting cells to their extracellular environment by sensing and transducing signals to activate cellular responses, such as those that occur during pathogen infection. This mini review will summarize current experimental approaches used to study cell wall functions during plant-pathogen interactions. Focus will be paid to cell imaging, spectroscopic analyses, and metabolic profiling techniques.

The Involvement Of J-Protein Atdjc17 In Root Development In Arabidopsis, Carloalberto Petti, Meera Nair, Seth Debolt

Horticulture Faculty Publications

In a screen for root hair morphogenesis mutants in Arabidopsis thaliana L. we identified a T-DNA insertion within a type III J-protein AtDjC17 caused altered root hair development and reduced hair length. Root hairs were observed to develop from trichoblast and atrichoblast cell files in both Atdjc17 and 35S::AtDJC17. Localization of gene expression in the root using transgenic plants expressing proAtDjC17::GUS revealed constitutive expression in stele cells. No AtDJC17 expression was observed in epidermal, endodermal, or cortical layers. To explore the contrast between gene expression in the stele and epidermal phenotype, hand cut transverse sections of Atdjc17 roots were …

Haploid Induction Via In Vitro Gynogenesis In Tomato (Solanum Lycopersicum L.), He Zhao, Xiao-Xuan Wang, Yong-Cheng Du, De-Wei Zhu, Yan-Mei Guo, Jian-Chang Gao, Fei Li, John C. Snyder

Horticulture Faculty Publications

In order to determine the potential for haploid induction via in vitro gynogenesis in tomato, the ovules and protoplasts of embryo sacs from the hybrids Zhongza 101 and Zhongza 105 were cultured. An efficient method of ovule isolation was established in this study. Using this method, 100-150 ovules could be isolated from one ovary. Isolated ovules were cultured on three induction media to induce gynogenesis in vitro. During culture, ovules were enlarged markedly, with opaque white color. When observed microscopically, there were cell divisions and cell clumps in embryo sacs. Subsequently, the cell clumps in embryo sacs ceased growth, likely …

Acetobixan, An Inhibitor Of Cellulose Synthesis Identified By Microbial Bioprospecting, Ye Xia, Lei Lei, Chad Brabham, Jozsef Stork, James R. Strickland, Adam Ladak, Ying Gu, Ian Wallace, Seth Debolt

Horticulture Faculty Publications

In plants, cellulose biosynthesis is an essential process for anisotropic growth and therefore is an ideal target for inhibition. Based on the documented utility of small-molecule inhibitors to dissect complex cellular processes we identified a cellulose biosynthesis inhibitor (CBI), named acetobixan, by bio-prospecting among compounds secreted by endophytic microorganisms. Acetobixan was identified using a drug-gene interaction screen to sift through hundreds of endophytic microbial secretions for one that caused synergistic reduction in root expansion of the leaky AtcesA6prc1-1 mutant. We then mined this microbial secretion for compounds that were differentially abundant compared with Bacilli that failed to mimic CBI action …

Effectiveness Of A Farm Field Trip, Bonnie S. Sigmon

Theses and Dissertations--Community & Leadership Development

The annual Sigmon Farm Tour was started in 1992 as an agricultural education program where students could experience being on a farm with the goal of increasing the agricultural literacy levels of the participants. Every year the entire 4th grade student population of Rockcastle County spends the day touring the farm and participating in experiential mini lessons given by the cooperating farm service and health agencies. The program has continued for 20+ years without an evaluation as to whether it is achieving its objectives. This evaluation will also exhibit the programs strengths and weakness so it can continue to improve. …

Reduced Inputs Turfgrass Through White Clover Inclusion, Bret Andrew Sparks

Theses and Dissertations--Plant and Soil Sciences

Most managed turfgrass species require frequent inputs to maintain an acceptable level of quality. Among these inputs, nitrogen (N) fertilization is usually the most limiting in terms of growth and development. However, N fertilization is also linked to non-point source (NPS) pollution. White clover (WC) is known for its ability to provide N when mixed into stands of turfgrass, and does not pose a threat for NPS pollution. Two field studies were designed to investigate the effects of WC inclusion in stands of cool-season turfgrasses. In the first field study, three cultivation techniques were examined for establishment of WC into …

An Intergenic Region Shared By At4g35985 And At4g35987 In Arabidopsis Thaliana Is A Tissue Specific And Stress Inducible Bidirectional Promoter Analyzed In Transgenic Arabidopsis And Tobacco Plants, Joydeep Banerjee, Dipak K. Sahoo, Nrisingha Dey, Robert Houtz, Indu B. Maiti

Kentucky Tobacco Research and Development Center Faculty Publications

On chromosome 4 in the Arabidopsis genome, two neighboring genes (calmodulin methyl transferase At4g35987 and senescence associated gene At4g35985) are located in a head-to-head divergent orientation sharing a putative bidirectional promoter. This 1258 bp intergenic region contains a number of environmental stress responsive and tissue specific cis-regulatory elements. Transcript analysis of At4g35985 and At4g35987 genes by quantitative real time PCR showed tissue specific and stress inducible expression profiles. We tested the bidirectional promoter-function of the intergenic region shared by the divergent genes At4g35985 and At4g35987 using two reporter genes (GFP and GUS) in both orientations in transient tobacco protoplast and …

Sorghum Mutant Rg Displays Antithetic Leaf Shoot Lignin Accumulation Resulting In Improved Stem Saccharification Properties, Carloalberto Petti, Anne E. Harman-Ware, Mizuki Tateno, Rekha Kushwaha, Andrew Shearer, A. Bruce Downie, Mark Crocker, Seth Debolt

Horticulture Faculty Publications

BACKGROUND: Improving saccharification efficiency in bioenergy crop species remains an important challenge. Here, we report the characterization of a Sorghum (Sorghum bicolor L.) mutant, named REDforGREEN (RG), as a bioenergy feedstock.

RESULTS: It was found that RG displayed increased accumulation of lignin in leaves and depletion in the stems, antithetic to the trend observed in wild type. Consistent with these measurements, the RG leaf tissue displayed reduced saccharification efficiency whereas the stem saccharification efficiency increased relative to wild type. Reduced lignin was linked to improved saccharification in RG stems, but a chemical shift to greater S:G ratios in RG stem …

Comparative Feedstock Analysis In Setaria Viridis L. As A Model For C4 Bioenergy Grasses And Panicoid Crop Species, Carloalberto Petti, Andrew Shearer, Mizuki Tateno, Mathew J. Ruwaya, Sue E. Nokes, Tom Brutnell, Seth Debolt

Horticulture Faculty Publications

Second generation feedstocks for bioethanol will likely include a sizable proportion of perennial C4 grasses, principally in the Panicoideae clade. The Panicoideae contain agronomically important annual grasses including Zea mays L. (maize), Sorghum bicolor (L.) Moench (sorghum), and Saccharum officinarum L. (sugar cane) as well as promising second generation perennial feedstocks including Miscanthus × giganteus and Panicum virgatum L. (switchgrass). The underlying complexity of these polyploid grass genomes is a major limitation for their direct manipulation and thus driving a need for rapidly cycling comparative model. Setaria viridis (green millet) is a rapid cycling C4 panicoid grass with a relatively …

Crystallization And Structure Of A Plant Peptide Deformylase, David W. Rodgers, Robert L. Houtz, Lynnette M. A. Dirk, Mark Williams

Horticulture Faculty Patents

This invention relates to the crystal structure of a plant peptide deformylase polypeptide and methods of using the structure to design compounds that modulate the activity of the polypeptide.

Plants And Plant Products Useful For Biofuel Manufacture And Feedstock, And Methods Of Producing Same, Seth Debolt, Darby Harris, Jozsef Stork

Horticulture Faculty Patents

A method of processing plant cellulose includes providing plant cellulose that is from a plant expressing a CESA polypeptide variant having at least one amino acid mutation in its carboxy-terminal transmembrane region; and saccharifying the plant cellulose to produce fermentable sugars. The method can also include fermenting the fermentable sugars to produce alcohol. A method of producing a plant having beneficial saccharification properties includes introducing into a plant a polynucleotide encoding a CESA polypeptide variant having at least one amino acid mutation in its carboxy-terminal transmembrane region; and expressing in the plant the CESA polypeptide variant, wherein plant cellulose of …