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Fusarium can cause very different symptoms on different plants under different environmental conditions. On some tropical plants, the pathogen can cause leaf spots, while on others like cyclamen vascular wilt is the most common symptom. In the Chase Horticultural Research diagnostic lab, we see Fusarium spp. Watch for Fusarium on basil, phormium, chrysanthemum, dianthus, mandevilla, lisianthus, cyclamen, dracaena, dieffenbachia and Christmas cactus Schlumbergera truncata. One of the most intractable diseases we have encountered in the lab is dieback of mandevilla and phormium caused by Fusarium spp.
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Carotenoids are a diverse group of pigments widely distributed in nature.The vivid yellow, orange, and red colors of many horticultural crops are attributed to the overaccumulation of carotenoids, which contribute to a critical agronomic trait for flowers and an important quality trait for fruits and vegetables.
Not only do carotenoids give horticultural crops their visual appeal, they also enhance nutritional value and health benefits for humans. As a result, carotenoid research in horticultural crops has grown exponentially over the last decade. These investigations have advanced our fundamental understanding of carotenoid metabolism and regulation in plants. In this review, we provide an overview of carotenoid biosynthesis, degradation, and accumulation in horticultural crops and highlight recent achievements in our understanding of carotenoid metabolic regulation in vegetables, fruits, and flowers.
Carotenoids are a subgroup of isoprenoids with more than members distributed in plants, algae, fungi, and bacteria. Carotenoids typically contain 40 carbons in their polyene backbones with conjugated double bonds and rings at the ends. The extensively conjugated double bonds allow carotenoids to absorb visible light, yielding yellow, orange, and red colors that make them the most conspicuous pigments in plants.
Color is an important quality trait for fruits and vegetables and a critical agronomic trait for flowers. The vivid yellow, orange, and red colors in many horticultural crops are attributed to high levels of carotenoid accumulation in chromoplasts.
Carotenoids are present in both photosynthetic and non-photosynthetic tissues of horticultural crops. In photosynthetic green tissues, carotenoids fulfill essential functions in photosynthesis for photosystem assembly, light harvesting, and photoprotection.
Carotenoids also serve as precursors for two important phytohormones, abscisic acids ABA and strigolactones, which are key regulators for plant development and stress response.While carotenoid content and composition are relatively consistent in green leaf tissues of plant species, carotenoid levels and constituents vary greatly in non-green tissues of horticultural crops even within the same species.
Therefore, various and multifaceted regulatory mechanisms are expected to exist in horticultural crops to control carotenoid metabolism and accumulation. Carotenoid research in the majority of horticultural crop species has focused largely on the regulation of carotenoid content and composition at transcriptional level of carotenogenic genes. There is an increasing amount of information available related to other aspects of regulation of carotenoid accumulation.
This review provides an overview of carotenogenesis and discusses recent advances in our understanding of the multiple levels of regulation of carotenoid accumulation in fruits, vegetables, and flowers. Carotenoids are synthesized in all types of differentiated plastids but accumulate in high levels in the chloroplasts of green tissues and the chromoplasts of roots, fruits, and flower petals.
However, the identification of the genes encoding carotenogenic enzymes is a more recent development from the past two decades. All the genes and enzymes that catalyze the core reactions of carotenoid biosynthesis and degradation have been identified in plants Figure 1. A large number of the pathway genes from various horticultural crops have been cloned and studied.
General carotenoid metabolic pathway in horticultural crops. Following several desaturation and isomerization steps, lycopene is produced. Metabolites are bolded and colored according to their compound colors, whereas black indicates no color. Enzymes and regulators are not bolded. Solid arrows indicate biosynthesis and dashed arrows indicate degradation PSY regulators are colored in blue. Dotted rectangles separate different groups of carotenoids.
Carotenoids, along with other plastid-synthesized isoprenoids, arise from the condensation of the 5-carbon precursors isopentenyl diphosphate and dimethylallyl diphosphate, which are produced via the plastidial 2- C -methyl- D -erythritol 4-phosphate MEP pathway in plastids. This step is considered to be the primary bottleneck in carotenogenesis.
The subsequent cyclization of the lycopene carbon chain ends starts the branch point of the pathway and represents a crucial step in carotenoid metabolism for generating carotenoid diversity Figure 1. The addition of oxygen by hydroxylases and epoxidases to cyclic carotenes produces xanthophylls Figure 1. However, in some plants, lutein can be converted into lutein epoxides by epoxidation, although the enzymes involved are not clear. Zeaxanthin is epoxidized to yield antheraxanthin and then violaxanthin.
Violaxanthin can be converted back to zeaxanthin by violaxanthin de-epoxidase, forming the ubiquitous violaxanthin cycle that is essential for plants to adapt to different light conditions. In red pepper and tiger lily, antheraxanthin and violaxanthin are converted by capsanthin-capsorubin synthase CCS into capsanthin and capsorubin, the main carotenoids that generate the characteristic red and orange colors of these species.
Carotenoids are catabolized enzymatically by a family of carotenoid cleavage dioxygenases CCDs; sometimes referred to as carotenoid cleavage oxygenases, CCOs to produce apocarotenoids, which control carotenoid turnover and contribute to the colors or aromas of flowers and fruits and the production of two important phytohormones, ABA and the strigolactones. Carotenoid composition and content vary widely in fruits, vegetables, and flowers Table 1 and have been subjected to extensive analysis.
In many cases, the genetic elements responsible for specific carotenoid accumulation are unknown. Varieties with different colors in a single species are often seen.Vegetables are one of the major sources of carotenoids for human consumption.
Tomato is widely used as a model system for carotenoid research. This crop displays diverse color variation in its fruit i. Red tomato is rich in lycopene, which constitutes ca. Pepper synthesizes carotenoids to give its fruits a range of red, yellow, and orange colors across diverse pepper species. Red fruit predominantly produces the characteristic carotenoid capsanthin.
Other vegetables that contain high levels of carotenoids include carrot, sweet potato, winter squash, orange cauliflower, and many dark green leafy vegetables.
Two major loci, Y and Y 2 , control much of the variation in carotenoid accumulation in carrot. Fruits are another major source of carotenoids for human consumption. A large number of fruits accumulate various carotenoids.
Melon fruit typically has white-, green-, or orange-colored flesh with relatively simple carotenoid compositions. The orange versus non-orange flesh color trait inheritance is controlled by a single gene, green-flesh , which was recently revealed to be the melon Or gene.
Generally, red-fleshed watermelon has the highest carotenoid content and contains lycopene as the major carotenoid. White-fleshed watermelon has only trace amount of carotenoids.
Citrus has the most diverse carotenoid composition with the largest number of carotenoid species found in any fruit. In flowers, carotenoids and anthocyanins govern flower petal color. The majority of carotenoids present in flower petals are xanthophylls Table 1. Yellow flowers generally contain large amounts of xanthophylls, along with their epoxides, and traces of carotenes, whereas orange flowers contain carotenes as their main carotenoids.
For example, lutein accumulates in high abundance in marigold and daffodil petals to yield an intense yellow color.Lutein and its epoxide are predominant in yellow chrysanthemum, 65 and violaxanthin and neoxanthin are predominant in the yellow Oncidium orchid.
In many horticultural crops, carotenoids accumulate in chromoplasts, which are classified as crystalline, globular, fibrillary, membranous, or reticulo-tubular based on various sequestering substructures within the chromoplasts. Carotenoid accumulation in chromoplasts is a net result of biosynthesis, degradation, and stable storage. Most studies on carotenoid regulation in non-model horticultural crops focus on the transcriptional regulation of carotenoid pathway genes.
Although new insights into various aspects and levels of regulation are emerging, the mechanisms underlying carotenoid biosynthesis and accumulation in the majority of horticultural crops are not well understood. Horticultural crops synthesize and accumulate diverse carotenoids with a wide range of contents in non-green organs. The first level of regulation of carotenoid biosynthesis in many vegetables, fruits, and flowers is via the control of biosynthetic gene transcription.
Transcriptional regulation is a major determinant for carotenoid production in the classical model systems of tomato and pepper during fruit ripening in response to developmental signals. In tomato fruit, the increased production of lycopene during fruit color change from green to red is preceded by the enhanced transcription of upstream genes for lycopene biosynthesis, i. Transcriptional regulation of biosynthetic genes also appears to play a central role in the control of carotenoid production for many other horticultural crops because of the correlated changes.
The important role of transcriptional regulation of biosynthetic genes in controlling carotenoid production is also evident in non-model horticultural crop mutants that accumulate specific carotenoids.A mutation in papaya LCYB2 dramatically reduces its expression, resulting in the accumulation of lycopene, and is responsible for the difference between red- and yellow-fleshed papaya.
The transcriptional regulation of carotenogenesis in flower petals has been discussed in previous reviews. In the white flowers of Ipomoea nil , lily and marigold, the expression of carotenoid biosynthetic genes is much lower than that of their pale-yellow and yellow petal varieties. The transcription of CHYB has also been suggested to be critical for the carotenoid differences between the white or pale-yellow and yellow flowers of Ipomoea plants 91 and in the stigmas of different Crocus species.
Gene promoters represent a critical element for the transcriptional regulation of gene expression. The functional analysis of carotenogenic gene promoters provides insights into the regulatory basis of carotenoid gene expression during fruit and flower development. The developmental upregulation of some carotenoid genes in both fruits and flowers appears to be linked with the specific activities of carotenogenic gene promoters in chromoplast-containing tissues.
The Great Yellow Gentian accumulates carotenoids with the synchronized upregulation of several carotenogenic genes during flower petal development. An examination of their promoters identified three common cis -acting motifs, which were suggested to be responsible for co-regulating the carotenogenic genes.
Although transcriptional regulation is important for carotenoid production in horticultural crops in response to developmental signals, the amount and type of carotenoids accumulated in some vegetables and fruits are not correlated with carotenogenic gene expression.Carotenoid accumulation disjoint from differential gene transcription has also been reported in many other cases, such as between white- and orange-fleshed squash, 51 during the fruit ripening of normal and red orange, 57 in yellow- versus red-fleshed watermelon, 21 and in flowers, such as between white and yellow marigold, 99 between white chrysanthemum and its yellow bud mutant, 65 and in lilies, 68 indicating the existence of different, additional regulatory mechanisms.
In comparison with the transcriptional regulation of carotenogenic genes, not much is known about the regulation of carotenoid biosynthetic enzymes in plants in general.
A number of mechanisms have been shown to modulate carotenogenic enzymes and their activities in regulating carotenoid biosynthesis, which include changes in amino acid sequences, membrane association, protein-protein interactions, suborganelle localization, and cofactors. The most common modulation of biosynthetic enzyme activity is the alteration of enzyme amino acid sequences, which results in enzymes with either enhanced or reduced activities.
For example, in the non-horticultural crop cassava, changing a single amino acid in a highly conserved region of PSY results in increased catalytic activity, leading to enhanced carotenoid production in yellow-rooted cultivars.
Carotenoid biosynthesis occurs in the plastidial membrane. The soluble form is enzymatically inactive in large HSPcontaining complexes in the stroma and only becomes active to induce carotenoid accumulation in flower petals when it is bound to the membrane. Dramatically increased carotenoid content during de-etiolation is associated with phytochrome-regulated PSY expression. During de-etiolation, the topological relocalization of PSY to the thylakoid membranes of chloroplasts leads to enzymatic activation and carotenoid biosynthesis.
Recent studies have also revealed other regulatory mechanisms to control biosynthetic enzyme protein levels and activities in model plants, such as post-transcriptional regulation via protein—protein interaction, which likely operates in horticultural crops. The OR protein was discovered in the orange curd cauliflower. OR variants regulate carotenoid accumulation in both cauliflower and melon fruit. DXS interacts directly with J-protein J20, which regulates DXS protein level and activity by recognizing inactive DXS and delivering it to the HSP70 chaperone system either for proper folding and enzyme activation or for proteolytic degradation under stress.
Carotenoid cleavage into apocarotenoids by CCDs or CCOs represents another important control to regulate carotenoid accumulation in horticultural crops.
UTIA Family, please refer utk. For UTIA-specific resources, please visit utia. A new certificate program through the University of Tennessee Herbert College of Agriculture will teach the history, benefits and practice of horticultural therapy to enhance the lives of those who may have limited access to outdoor environments, including the elderly and those with some medical conditions. Students enrolled in the mostly online program will learn how to use horticultural therapy techniques to help others; how to design accessible outdoor and indoor spaces; and budgeting, marketing and other key components of running successful horticultural therapy programs.
Second, quality measures made by research-ers in horticulture are generally related they are difficult to return after pur-chase (Eiglier et al., ).
This past September, Dr. The trio originally discussed writing the book nine years ago at OFA Short Course — before it was rebranded as Cultivate — and have been working on the book for the past several years.Cloyd, an extension specialist at Kansas State University, wrote the section about pests, while Daughtrey, a senior extension associate at Cornell University, and Chase, president of Chase Horticultural Research co-wrote the sections covering diseases. It is not currently available in a digital format. Raymond Cloyd: Growers have really diversified. Now, you have growers producing vegetables and other plants at the same time. Although I think that while the bedding plant industry is doing well and crops like new guinea impatiens are so popular, growers are diversifying because of the market and trying to find new niches. The same logic applies to vegetables.
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New Paper in the Review of Palaeobotany and Palynology.
She graduated with a B. In , she joined the faculty at the University of Florida, Central Florida Research and Education Center at Apopka as an assistant professor to conduct research on diseases of ornamentals, including foliage, cut foliage, bedding, and woody crops. By , she had earned the rank of professor and also served as assistant director of the Research and Education Center at Apopka — In , Chase retired from the University of Florida and was awarded professor emeritus status. She started a family-based contract research business in California, Chase Horticultural Research, where she continues to serve as president. Chase is a widely recognized expert of diseases of annual and perennial ornamental crops.
More Information ». White and her laboratory work to evaluate the use of plant and bio-based treatment technologies to manage nutrient pesticide, and plant pests carried in irrigation water. She is particularly interested in helping growers clean water so that it can be reused on-farm. White is Project Director for this grant. Reviewer - multiple journals.White manages and conducts research projects and conveys information related to water management, water quality chemical and biotic parameters , ecologically-based treatment technologies, and integrated pest management to green industry stakeholders.
Free and open company data on California (US) company HORTICULTURAL RESEARCH, INC. (company number C), E. ANGELA STREET PLEASANTON CA
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Like pioneers in the earliest days of our nation, 36 students and three faculty members ventured west to Fort Collins, Colorado, and scaled the Great Rocky Mountains. Except this snowshoe trek was an early team building exercise to inspire and refocus before participating in the 44th National Collegiate Landscape Competition hosted by Colorado State University. The National Collegiate Landscape Competition unites over students from 64 colleges and universities with green career, industry and manufacturer leaders. For five full days of spectacular coordinated events filled with competitions, workshops, exhibits and a career fair with over companies recruiting. The competition includes 29 individual and team events in all aspects of landscape horticulture.
Just in time, because we need a new generation of fruits and vegetables.
On Jan. OHP Inc. Marengo has received federal EPA registration, is registered in many key states and is available for immediate shipment through authorized OHP distributors. The acquisition, which closed December 31, , will result in a significantly stronger product offering for Nufarm. This division, headquartered in Naperville, Ill.
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