"The in vitro addition of plant growth regulators (i.e. phytohormones) to Agrobacterium transformed hairy root cultures affects morphological and biochemical changes, resulting in altered growth and secondary metabolite accumulation rates in root tissues. Significant increases in both growth and secondary product accumulation have been observed, upon incubation with phytohormones, in some species. Consequently, the use of phytohormones in vitro has received increasing attention as a potential means for increasing those plant secondary products notoriously produced in small quantities. However, currently little is known about the specific effects of phytohormones on growth and secondary metabolism. The Chinese herb Artemisia annua L. produces artemisinin, an effective antimalarial therapeutic. Efforts to increase the amount of artemisinin via chemical synthesis or field-grown crops have met with huge costs and disappointingly low yields, respectively. Agrobacterium transformed hairy root cultures of A. annua (Clone YUT16) produce artemisinin and undergo rapid growth compared to non-transformed, making them a good model system to study secondary metabolite production. Demonstrated herein is the first definitive evidence, by any hairy root species, of a favorable response to exogenous combinatorial hormone application as well as the development of a two-stage culture system alluding to optimal growth and artemisinin production conditions in A. annua hairy roots. Furthermore, analysis of artemisinin and biomass accumulation in A. annua hairy roots in the presence of phytohormones has revealed effective individual as well as combinatorial phytohormone concentrations suitable for increasing single and bulk root growth, and artemisinin production. The effectiveness of an optimal phytohormone combination, with respect to time of addition, its relationship to inoculum size, and its combination with the provision of fresh nutrients and or mechanical stress to the roots is also described resulting in artemisinin yields of up to 0.8 ìg/g F.W. Although the findings contained herein are not yet optimized they do, however, argue for the potential usefulness of a two-stage production scheme using phytohormones to increase plant secondary metabolite production in vitro."

The Bromeliaceae is one of the largest and most ecologically diverse angiosperm families in the Neotropics. In recent years, this family has begun to emerge as a model system for the study of plant evolutionary ecology and physiology, and major advances have been made in understanding the factors involved in episodes of rapid diversification and adaptive radiation in specific bromeliad lineages. However, despite a long tradition of ecophysiological research on the Bromeliaceae, an integrative, evolutionarily-contextualised synthesis of the links between anatomical) physiological, and ecological aspects of bromeliad biology has hitherto been lacking. The overarching aim of this research project was therefore to use new quantitative data representing a wide range of bromeliad taxonomic and functional groups to elucidate how variation in leaf traits connected by structure-function relationships influences ecological differentiation among bromeliad taxa. Special emphasis was placed on hydraulic and water relations traits because of fast-paced contemporary developments in these fields. The methodologies employed included an assessment of the diversity of bromeliad hydrological habitat occupancy, quantification of key anatomical and physiological traits and their correlations, investigation of the links between vascular and extra-xylary anatomy and hydraulic efficiency and vulnerability, quantification of stomatal sensitivity to leaf-air vapour pressure deficit and stomatal kinetics, and a case study of trait-mediated niche segregation among congeneric epiphytic bromeliad species on the Caribbean island of Trinidad. The results highlight how divergences in a range of continuous and categorical anatomical traits underpin differences in physiological capacities and sensitivities, which in turn determine environmental relations and ecological distinctiveness. This research project therefore provides critical insights into the mechanistic basis of evolutionary diversification in a highly ecologically important family. It also represents the most comprehensive analysis of the significance of trait variation for ecological differentiation across any major radiation of herbaceous angiosperms.

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WRKY transcription factors (TFs) belong to a large family of regulatory proteins in plants that modulate many plant processes. Extensive studies have been conducted on WRKY-mediated defense response in Arabidopsis thaliana and many crop species. This study aims to investigate the potential roles and contributions of WRKY TFs regulation in improving defense response in the resynthesized Arabidopsis allotetraploids (Arabidopsis suecica) from two related autotetraploid progenitors, Arabidopsis thaliana (At4) and Arabidopsis arenosa (Aa). Upon infection by Pseudomonas syringae (Pst), the allotetraploids has showed enhanced resistance against the pathogen when compared to the parents. Rapid induction of WRKY18, WRKY40, WRKY38, WRKY53, WRKY6; MAP kinase pathway related genes, WRKY33, PAD3; SA-pathway related genes, ICS1, EDS1, PBS3, MYB31; was evident in response to Pst and salicylic acid treatment in the allotetraploids. Cleaved amplified polymorphic sequences analysis further revealed that the AtWRKY18, AaWRKY40, AtWRKY33, and AtWRKY60 alleles expressed at higher levels when compared to their respective homoeologs in the allotetraploids, suggesting potential altered protein-protein interaction networks in the hybrids. Therefore, a split-luciferase complementation assay was used to characterize and quantify protein-protein interaction among these homoeologous WRKYs in the allotetraploids. Results showed that preferential protein-protein interactions exist for the cis-interacting AtWRKY18/AtWRKY18 homodimer or trans-interacting AtWRKY18/AaWRKY40 heterodimer when compared to the respective interacting complexes. In addition, differential affinities of WRKY18 and WRKY40 homo- and hetero- dimers toward the W-boxes at the WRKY60 promoter were observed. In the allotetraploids, PR1 expression was repressed under basal state when compared to the progenitors. Although PR1 is expressed at a higher level in A. thaliana, its expression fold change was higher and faster in the all otetraploids upon salicylic acid treatment. Transient expression of WRKY18 or WRKY40 homodimer in various combinations induced differential expression of PR1 gene in their respective wrky18 and wrky40 Arabidopsis thaliana mutants. In contrast, similar PR1 induction by homodimer in various combinations was observed when they were transiently expressed in the allotetraploids. In addition, transgenic AtWRKY18 overexpression plant displayed enhanced disease resistance against Pst when compared to AaWRKY18 overexpression lines. Such enhanced disease resistance was found to associate with the higher expression of PR1 and PR2 in AtWRKY18 transgenic lines. Moreover, differential Pst-induced expression of the direct targets (ICS1, EDS1 and PBS3) of WRKY18 in the Arabidopsis AtWRKY18 and AaWRKY18 overexpressors supported a biological difference between the At and Aa homodimers in mediating the targets regulation, thus contributing to the difference in disease responses. Overall, our findings suggested that the rapid differential alleles expression and altered protein-protein or protein-DNA interactions of WRKY transcription factors could contribute to the improved defense in the allotetraploids, providing a molecular basis of for heterotic phenotype development in hybrids.

Wheat is a crop of global importance accounting for 20% of global calorie consumption and a similar percentage of the daily protein for 2.5 billion people in less developed countries. To meet the food production demands of a predicted global population of 9 billion people by 2050, wheat yields need to increase by 1.7% per annum, whilst facing the added pressures of reduced fertilizer inputs and potentially reduced land availability. Plant root systems are key for efficient water and nutrient uptake and thus have a direct impact on yield, and yet there has been competitively little research into root system improvement. A high-throughput root phenotyping pipeline for wheat seedlings was designed consisting of a germination paper-based growth system combined with image segmentation and analysis software. A number of lines from the A.E. Watkins landrace population were characterised to test the final pipeline design. The pipeline was then utilized to phenotype a population of 94 lines from a doubled haploid population for quantitative trait loci (QTL) discovery. In total, 29 root QTL were discovered, with 2 loci co-localising with QTL for grain yield and nitrogen uptake efficiency discovered in field trials. Modern wheat varieties may have limited genetic diversity, due to changes in ploidy throughout evolution and subsequent domestication. With this in mind, thirty five ancient wheat relatives and eighteen amphidiploid hybrids were phenotyped for seedling root architectural traits, to determine the amount of phenotypic variation within ancient wheat species, and whether this variation can be transferred to modern varieties. The utilization of seedling root trait phenotyping is discussed and future research directions are identified.

In many parts of the world soils have been found that have apparently been formed under climatic conditions that no longer exist. In many places in northern Utah in areas associated with ancient Lake Bonneville, deep soils, fine-textured and non-calcareous, have been observed immediately above the highest shore line of the ancient lake. These soils have essentially no free carbonates to depths ranging from 4 to 15 feet, even though they exist on relatively steep slopes. In Davis and Utah Counties, soils having these characteristics have been given the tentative series name, Manila.

Tall wheatgrass Agropyron elongatum (Host) Beauv. has gained in importance since its introduction into the United States in 1909 from its native habitat on saline meadows and seashores of Southern Europe and Asia Minor. This very 1late-maturing, coarse, nonlodging 2 1/2 to 6-foot-tall bunchgrass was discarded in Utah in 1919 for being too aggressive. It is now under production in the intermountain and other regions because of its cold and drought tolerance as well as for its salt tolerance and its ability to make excellent fall and spring recovery. According to Weintraub (1953) this salt-tolerant plant gives high yields of forage on sub-irrigated alkaline soils.

The short-term effects of manganese toxicity on ribulose 1,5 bisphosphate carboxylase (Rubisco) activity and concentration in tobacco chloroplasts were examined. The activity of the enzyme from both manganese-treated and control plants was determined 6, 12, 18, 24 , and 48 h after introduction of manganese (80 mg/Li. Enzyme activity was determined by monitoring rates of radioactive CO2 fixation into acid stable products. A slight stimulation of the enzyme's activity was noted in experimental plants after 18 h of exposure to manganese as compared with control plants. A decrease in the enzyme's activity in experimental plants was noted after 48 h of exposure. Visible symptoms such as chlorosis and decreased leaf size were also observed after 48 h of manganese exposure in experimental plants. Using Rocket Immunoelectrophoresis, no appreciable difference between Rubisco concentration levels of the experimental plants and the control plants was noted after 6, 12, 18, 24, and 48 h of manganese exposure indicating that the effect on Rubisco activity is a post-translational phenomenon and that Rubisco is not being degraded at an accelerated rate. Even after 7 d of exposure to high manganese concentrations, when visible symptoms such as chlorosis and necrotic lesions were very evident, the level of Rubisco in the manganese-treated plants varied little from the levels in the control plants. Manganese accumulated in the experimental plants to concentrations as high as 3282 mg,/g dry wt as determined by atomic absorption spectrophotometry. A shuttling mechanism for manganese between young and old leaves was indicated by an observed decrease in the concentration of manganese in the young leaf tissue between 12 and 18 h after treatment .

Plant breeding and the development of new or better varieties of plants are essential parts of modern agronomy, horitculture and forestry. The basis for such improvement is a knowledge of the factors and principles of genetics. A number of genetic studies have been made with barley in recent years. This is partly because of the commercial importance of the crop, and partly because of the many distinct heritable characters of barley plants. The cultivated species of barley offers the plant breeder and geneticist a wealth of material for genetic studies. Varieties differ in a great many readily distinguishable characters, species hybridize readily, and their small number of chromosomes make it good material for inheritance studies. The barly genetic work has been divided among the principal workers in the U.S., each being responsible for one linkage group. This station has been assigned group IV of which this study is a part. A study of the inheritance of other genes not located in linkage group IV, but appearing in the crosses used, has also been made. This investigation is a by-product of the cereal breeding and improvement program being carried on at the Utah Agricultural Experiment Station.

Precision irrigation scheduling is one approach that can conserve water by supplying crops with the minimum amount of water needed for sufficient vegetative growth and final crop yield. Improved methods for irrigation scheduling are needed for arid regions that rely mainly on irrigation for crop water needs, and humid regions that supplement water received from precipitation with added irrigation. Methods that directly determine plant physiological responses to water availability have potential to be significantly more sensitive and accurate than indirect approaches like soil moisture measurement. Stomatal conductance is a rapid physiological response to leaf water potential. Stomatal conductance in single leaves has long been calculated using biophysical and energy balance principles. This same biophysical approach can be extended to plant communities using: 1) standard meteorological measurements, 2) accurate measurement of average canopy temperature, and 3) knowledge of canopy architecture. Here we use a model designed to separate the energy balance of the soil and plant canopy for the calculation of stomatal conductance (gC) in row crops. This model is modified for application in row crops which differ in their spatial distribution when compared to more uniform crops such as turfgrass or alfalfa. The energy balance model requires measurement or estimation of the soil and canopy temperatures. Various methods can be used to derive these temperatures, i.e., using a composite temperature of the two and either directly measuring or estimating one of the temperatures to derive the other, or directly measuring both component temperatures. This study compares two methods to determine which one is more appropriate in determining canopy temperature for calculation of canopy stomatal conductance for the measurements taken on the fields studied. By using the necessary environmental measurements, and model modifications, gC was continuously determined for 10 corn and 6 cotton crops throughout the Midwest and Southern United States. This gC value was then compared to a calculated reference gC for a well-watered crop. This reference gC represents the stomatal conductance of a well-watered crop experiencing no water stress. The ratio of the calculated and reference gC is an indicator of crop water status, which is called the stomatal conductance ratio (SCR). The SCR increased closer to one (indicating minimal water stress) after each irrigation or significant precipitation event, and steadily declined until the next irrigation event. Significant drought stress occurred in several of the fields. Daily SCR values were weighted to correspond with growth stage sensitivity to drought stress. These weighted values were highly correlated with yield (r2 values up to 0.79). SCR values for cotton were also highly correlated with yield (r2 values up to 0.96). This biophysical approach has the potential to provide a powerful tool for precision irrigation management. Growers can more efficiently apply water to their crops and more accurately determine when to apply irrigation.