Progress 10/01/07 to 09/30/13
Outputs
Target Audience: Crop production in the southeastern US is severely limited by low and high temperature and water deficit conditions. We are in the process of gaining a better understanding of the drought stress mechanisms of cucurbit crops. We are isolating important factors that respond to stress and lead to better plant acclimation responses. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Faculty member retired during final project year. no reported accomplishments.
Publications
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Progress 01/01/12 to 12/31/12
Outputs
OUTPUTS: Research was continued on functional analysis of stress responsive transcription factors (NAC) from Citrullus colocynthis, a very drought tolerant cucurbit species. Transient protoplast transformation of the cloned NAC genes confirmed nuclear localization. Gene expression analysis of the NAC transcription factors revealed that both genes were highly expressed in floral organs, more so than in shoots and roots. CcNAC1 was less induced following drought, salt and hormone treatments, while CcNAC2 showed high expression levels following different hormonal treatment and stress conditions. Promoter analysis pointed to a possible role of the CcNACs in photomorphogenesis. The 454 transcriptome sequencing project of Castanea pumila var. pumila, the Allegheny chinkapin, yielded a species specific single nucleotide (SNP) marker which can be used to detect hybridization occurring American Castanea species in the Appalachian forest ecosystem. The C. pumila transcriptome covers a wide range of biological processes, with 9% of the identified genes in response to abiotic and biotic stimuli. Transcript abundance was especially high in genes associated with several well-known plant defense pathways such as phenylpropanoid metabolism, phytohormone signaling and hypersensitive response pathways. A large fraction of the contigs (20.8%) matched chloroplast genes and a C. pumila specific chloroplast genome was assembled. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Crop production in the southeastern US is severely limited by low and high temperature and water deficit conditions. We are in the process of gaining a better understanding of the drought stress mechanisms of cucurbit crops. We are isolating important factors that respond to stress and lead to better plant acclimation responses. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Water deficit and temperature (low and high) stress are considered the main environmental stresses of plants causing a major constraint on plant growth and development. Tolerance to stress is complex. We have isolated genes from a drought tolerant cucurbit species (Citrullus colocynthis) to gain a better understanding of the molecular stress mechanisms of this plant. Our focus is on plant-specific NAC transcription factors which impact the expression of genes plants use during adaptation to stress. The role of the CcNAC genes will be further studied in Arabidopsis. A 454 next- generation DNA sequencing project was used to develop species specific markers so the incidence and level of hybridization between American chestnut and Allegheny chinkapin can be studied in populations occurring in the Appalachian forest ecosystem.
Publications
- Dehghani, H., Feyzian E., Jalali M., Rezai, A., and F. Dane. 2012. Use of GGE biplot methodology for genetic analysis of yield and related traits in melon (Cucumis melo L.). Canadian Journal of Plant Science 92: 77-85. Li, X., and F. Dane. 2013. Comparative chloroplast and nuclear DNA analysis of Castanea species in the southern region of the USA. Tree Genetics and Genomes 9: 107-116. Wang, Z., and F. Dane. 2013. NAC (NAM/ATAF/CUC) transcription factors in different stresses and their signaling pathway. Acta Phyiologia Plantarum DOI 10.1007/s11738-012-1195-4
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Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: Research was continued on the isolation and characterization of several stress responsive transcription factors (NAC) in Citrullus colocynthis, a very drought tolerant cucurbit species. Two NAC genes were isolated and cloned and their subcellular location was investigated. Investigations were conducted focused on the effects of freeze-pruf, a foliar spray designed to boost the plant's cold acclimation potential, on Satsuma seedlings. Results from experiments with different Satsuma seedlings sprayed with water or freeze-pruf followed by cold treatment did result in similar levels of cold injury and mortality. A 454 transcriptome sequencing project was initiated for Castanea pumila var. pumila, the Allegheny chinkapin, for development of species specific single nucleotide polymorphisms to detect the incidence and level of hybridization occurring American Castanea species in the Appalachian forest ecosystem. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Crop production in the southeastern US is severely limited by low and high temperature and water deficit conditions. Cold and drought stress have important impacts of plant growth, fruit quality and quantity. Expansion of the Satsuma mandarin industry in the Gulf Coast regions is constrained by the risk of freeze damage. We studied the impact of a foliar spray (freeze-pruf), designed to boost the plant's resistance to cold, on Satsuma seedlings by exposing plants to freeze-pruf or water followed by cold treatment. We concluded that freeze-pruf had little to no impact on the prevention of cold injury. We are in the process of gaining a better understanding of the drought stress mechanisms of cucurbit crops. We are isolating important factors that respond to stress and lead to important plant acclimation responses. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Water deficit and temperature (low and high) stress are considered the main environmental stresses of plants causing a major constraint on plant growth and development. Tolerance to stress is complex. We have isolated several genes from a drought tolerant cucurbit species (Citrullus colocynthis) to gain a better understanding of the molecular stress mechanisms of this plant. Our focus is on plant-specific NAC transcription factors which impact the expression of genes plants use during adaptation to stress. The effectiveness of a topical spray (freeze-pruf) which was developed to enhance a plant's resistance to cold injury was tested on Satsuma seedlings exposed to cold treatment. Cold injury and mortality levels of Satsuma plant foliage was not significantly influenced by freeze-pruf. The 454 next generation DNA sequencing project aims to develop specific specific markers so the incidence and level of hybridization between American chestnut and Allegheny chinkapin can be studied in populations occurring in the Appalachian forest ecosystem.
Publications
- Huang Y, Y. Si and F. Dane 2011. Impact of grafting on cold responsive gene expression in Satsuma mandarin (Citrus unshiu). Euphytica 177:25-32. Dane, F. Molecular domestication and phylogeography ofcucurbit species. 2011. Plant Archaeogenetics. Chapter 9. G. Gyulai (Ed). pp 105-114. Nova Science Publishers, Inc. NY.
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: Investigations were conducted focused on understanding the impact of grafting on cold-responsive gene expression in Satsuma mandarin (Citrus unshiu), C. unshiu grafted on Poncirus trifoliata rootstock and P. trifoliata following exposure to low temperature treatments. The focus was on nutrient and auxin signaling pathways. Studies are in progress to determine the effect of freeze-pruf, a foliar spray designed to boost the plant's cold acclimation potential, on cold-responsive gene expression in citrus species. Research was continued on isolation and characterization of several drought responsive genes from Citrullus colocynthis, a drought tolerant cucurbit species. A respiratory burst oxidase gene was cloned. The protein functions in the production of reactive oxygen species. The subcellular location of Ccrboh was investigated by transient expression of a 35S::Ccrboh::GFP fusion construct in protoplasts. The result confirmed that Ccrboh is a transmembrane protein. Our data suggest that the Ccrboh gene might be functionally important during the acclimation of plants to stress and also in plant development and holds promise for improving drought tolerance of other cucurbit species. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Citrus production in the southeastern US is severely limited by low temperature conditions. Cold stress has important impacts on plant growth, fruit quality and quantity. Expansion of the Satsuma mandarin industry in the Gulf Coast regions is constrained by the risk of freeze damage. Satsuma mandarins are usually grafted onto cold hardy rootstock (Poncirus trifoliata) which can withstand temperatures as low as -26C when cold-acclimated. The impact of grafting on gene expression in the Satsuma scion is poorly understood. In this study we have compared gene expression in Satsuma mandarin seedlings with Satsuma seedlings grafted onto Poncirus rootstocks and Poncirus seedlings during exposure to low temperatures. Species specific differences in the expression of several cold-responsive genes were observed, which might be associated with the partitioning of nutrients and plant hormones. A better understanding of the signaling pathway between rootstock and scion might provide us with new strategies to improve the cold tolerance ability of economically important fruit crops. Water deficit is considered the main environmental stress of plants. Tolerance to drought is a complex phenomenon. One cucurbit species (Citrullus colocynthis) is well adapted to drought and is presently being used as a model to study the molecular responses of this species to drought. Comparisons are being made to the expression of drought-responsive genes in the closely related watermelon (C. lanatus). This should lead to better insights toward the development of stress-tolerant watermelon cultivars. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Low temperatures are a continuing threat to the Satsuma mandarin industry in the Gulf Coast region. The availability of improved Satsuma mandarin cultivars, cold-hardy Poncirus trifoliata rootstocks and better methods of tree protection has fueled an increased interest in Satsuma mandarin production. Investigations were conducted to study the impact of grafting on expression of several different cold-responsive genes in Satsuma mandarin, Satsuma mandarin grafted onto Poncirus rootstock and Poncirus seedlings exposed to low temperatures. The rootstock did affect expression of genes in the Satsuma mandarin scion, which might be associated with partitioning of nutrients and auxin. Development of freeze tolerance in citrus production is very important and will enhance the competitiveness of the crop. It might also allow the establishment of orchards in more northerly direction and result in increased acreage. Water deficit is considered the main environmental stress of plants and a major constraint on plant growth and productivity. Tolerance to drought stress is complex. Production of reactive oxygen species (ROS) at the cell surface is one of the earliest events detected in the plant defense response. The respiratory burst oxidase homologue (Rboh) functions in the production of ROS. This protein accumulates to high levels in drought tolerant Citrullus colocynthis, but not in C. lanatus, the watermelon. Grafting of C. lanatus onto C. colocynthis rootstock effects expression of the gene in the scion. Thus this gene might be important during acclimation to stress in plants and warrants further investigation.
Publications
- Si, Y., F. Dane, A. Rashotte, K. Kang, and N.K. Singh. 2010. Cloning and expression analysis of the Ccrboh gene encoding respiratory burst oxidase in Citrullus colocynthis and grafting onto Citrullus lanatus (watermelon). Journal of Experimental Botany 61: 1635-1642.
- Huang, Y., Y. Si, F. Dane. 2011. Impact of grafting on cold responsive gene expression in Satsuma mandarin (Citrus unshiu). Euphytica 177:25-32.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: The impact of grafting on cold-responsive gene expression was studied in Satsuma mandarin (Citrus unshiu), C. unshiu grafted on Poncirus trifoliata rootstock and P. trifoliata following exposure to cold shock or cold acclimation treatments. Major changes in gene expression occurred in the different species during cold stress especially with respect to nitrate transporter, auxin responsive GH3, UDP-glycosyl transferase and chalcone-flavanone isomerase. Very high levels of nitrate transporter were reached early in Poncirus following 60 hours of cold shock treatment at 4C, and in C. unshiu after 3 weeks of gradual cold acclimation. Also, high levels of auxin responsive GH3 were reached in Poncirus following both cold shock and cold acclimation treatment, while very low levels were observed in C. unshiu. Poncirus rootstock significantly affected gene expression in the C. unshiu scion, resulting in a reduction of nitrate transporter, UDP-glycosyltransferase and trehalose 6-phosphate synthase expression levels, and an increase in auxin responsive GH3 gene during cold acclimation. The impact of rootstock on citrus scion during cold stress might be associated with partitioning of nutrients PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Commercial citrus production in the southeastern US is severely limited by low temperature conditions. Economic losses to citrus crop commodities from cold stress in the last 10 years can be conservatively estimated in the billions of dollar range. Consequently, cold stress has one of the most economically important impacts on plant growth, and fruit quality and quantity. Satsuma mandarin is one of the most cold-hardy citrus species, but it cannot survive temperatures below -10C. Thus expansion of the Satsuma mandarin industry in the Gulf Coast regions of the US is constrained by the risk of freeze damage. Satsuma mandarins are usually grafted onto a cold-hardy rootstock, Poncirus trifoliata, which can withstand temperatures as low as −26C when cold-acclimated. Rootstocks do provide fruit growers with a tool to manipulate disease resistance, vigor, performance, and cold hardiness. The impact of grafting on gene expression in the scion is little understood. In this study we compared cold responsive genes in Satsuma mandarin, Satsuma grafted onto Poncirus and Poncirus following exposure to cold shock and gradual cold acclimation treatments. Species specific differences in expression levels and differences between grafted and non-grafted Satsuma seedlings were detected. These differences might be associated with the partitioning of nutrients and hormones. A better understanding of the signaling pathway between rootstock and scion and identification of factors limiting the acquisition of freezing tolerance should provide insights into strategies that impart higher levels of cold tolerance to economically important fruit crops. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Cold response in citrus is a complex regulation of different cellular events. The ability to cold acclimate is a polygenic trait involving a large number of genes, whose expression is controlled by low temperature. Alterations in the expression levels of these genes lead to numerous molecular and physiological changes. Changes in gene expression during cold acclimation and cold shock of P. trifoliata cultivar Flying Dragon, Satsuma mandarin cultivar Owari and Owari grafted onto Poncirus rootstock were analyzed to gain a better understanding of the effects of signal transduction on gene expression between rootstock and scion. Differences were detected between species especially in their response to cold acclimation. The impact of rootstock on citrus scion during cold stress might be associated with partitioning of nutrients since most changes occurred in expression levels of auxin responsive GH3 and nitrate transporter. More studies are needed to understand whether the nitrate transporter participates directly or indirectly in a nitrate and auxin signaling pathway. A better understanding of these pathways and identification of factors limiting the acquisition of freezing tolerance should provide insights into strategies that impart higher levels of cold tolerance to economically important fruit crops.
Publications
- Huang, Y. 2009. Impact of grafting on cold responsive gene expression in Citrus unshiu. MSc thesis Auburn University, AL 36849
- Si, Y., C. Zhang, S. Meng, and F. Dane. 2009. Gene expression changes in response to drought stress in Citrullus colocynthis. Plant Cell Reports 28: 997-1009.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Gene expression analysis of Poncirus trifoliata, Citrus unshiu and C. unshiu grafted onto P. trifoliata were studied in response to 10, 24, and 55 hours of low temperature (4C) and a gradual cold acclimation treatment. Relative quantitative-PCR was used. Emphasis was on genes with the following known functions: signal transduction, osmotic regulation and oxidative stress. Differences in gene expression were detected among species, and among ungrafted and grafted C. unshiu, suggesting exchange of signals between rootstock and scion. These comparisons provide information on the dynamic changes occurring in the scion in the transport of nitrate, regulation of sugars, and hormonal action as a result of grafting on a cold-tolerant rootstock. PARTICIPANTS: Ying Huang, a Master of Science student in the Department conducted the research as partial requirement for her graduate studies. TARGET AUDIENCES: Presentation on "Unraveling cold stress response mechanisms in Satsuma" was provided at the Deep South Fruit and Vegetable Growers Meeting in December 2008 to inform growers of research results. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
In the Satsuma industry in Alabama, tolerance to low temperature is an important determinant of the economic viability of fruit crop production and post harvest quality. Characterization of the cold reponse pathway in Poncirus and its role in conferring cold stress tolerance to the Satsuma mandarin scion will give us a better understanding of the mechanisms of cold acclimation. Manipulation of this pathway holds great promise for improving productivity of the Satsuma mandarin industry along the Gulf Coast region.
Publications
- Meng, S., F. Dane, Y. Si, R. Ebel, and C. Zhang. 2008. Gene expression analysis of cold treated versus cold acclimated Poncirus trifoliata. Euphytica 164: 209-219.
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Progress 01/01/07 to 12/31/07
Outputs
cDNA-AFLP and relative quantification-PCR were used to study gene expression in <i>Poncirus trifoliata</i> in response to 10, 24, and 55 hours of low temperature (4C) and a gradual cold acclimation treatment. Several differentially expressed genes were chosen for further study. These fragments show high similarity to genes with the following known functions: signal transduction and regulation of gene expression, osmotic stress response, cell skeleton reorganization, vesicle trafficking and senescence. Studies were initiated to determine gene expression levels in cold treated <i>Citrus unshiu</i> grafted on <i>P. trifoliata</i> rootstock. Genes differentially expressed under low temperature conditions will be cloned and characterized.
Impacts
In the Satsuma industry in Alabama, tolerance to low temperature is an important determinant of the economic viability of fruit crop production and post harvest quality. Characterization of the cold reponse pathway in <i>Poncirus</i> and its role in conferring cold stress tolerance to the Satsuma mandarin scion will give us a better understanding of the mechanisms of cold acclimation. Manipulation of this pathway holds great promise for improving productivity of the Satsuma mandarin industry along the Gulf Coast region.
Publications
- No publications reported this period
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