Ji-Yi Zhang | Bayer - Academia.edu (original) (raw)

Papers by Ji-Yi Zhang

Frontiers in Plant Science, 2016

High biomass production and wide adaptation has made switchgrass (Panicum virgatum L.) an importa... more High biomass production and wide adaptation has made switchgrass (Panicum virgatum L.) an important candidate lignocellulosic bioenergy crop. One major limitation of this and other lignocellulosic feedstocks is the recalcitrance of complex carbohydrates to hydrolysis for conversion to biofuels. Lignin is the major contributor to recalcitrance as it limits the accessibility of cell wall carbohydrates to enzymatic breakdown into fermentable sugars. Therefore, genetic manipulation of the lignin biosynthesis pathway is one strategy to reduce recalcitrance. Here, we identified a switchgrass Knotted1 transcription factor, PvKN1, with the aim of genetically engineering switchgrass for reduced biomass recalcitrance for biofuel production. Gene expression of the endogenous PvKN1 gene was observed to be highest in young inflorescences and stems. Ectopic overexpression of PvKN1 in switchgrass altered growth, especially in early developmental stages. Transgenic lines had reduced expression of most lignin biosynthetic genes accompanied by a reduction in lignin content suggesting the involvement of PvKN1 in the broad regulation of the lignin biosynthesis pathway. Moreover, the reduced expression of the Gibberellin 20-oxidase (GA20ox) gene in tandem with the increased expression of Gibberellin 2-oxidase (GA2ox) genes in transgenic PvKN1 lines suggest that PvKN1 may exert regulatory effects via modulation of GA signaling. Furthermore, overexpression of PvKN1 altered the expression of cellulose and hemicellulose biosynthetic genes and increased sugar release efficiency in transgenic lines. Our results demonstrated that switchgrass PvKN1 is a putative ortholog of maize KN1 that is linked to plant lignification and cell wall and development traits as a major regulatory gene. Therefore, targeted overexpression of PvKN1 in bioenergy feedstocks may provide one feasible strategy for reducing biomass recalcitrance and simultaneously improving plant growth characteristics.

Forages play a key role in ruminant livestock production and environmental protection. Because fo... more Forages play a key role in ruminant livestock production and environmental protection. Because forage grasses and forage legumes often grow in marginal areas, stress tolerance is one of the most important traits in forage cultivar development. Conventional and genetic engineering approaches have been used to improve stress tolerance of forage grasses and legumes. This review summarizes recent advances in improving drought and salt tolerances of several major forage species

The Plant Journal, 2005

The identification of leaf wax genes involved in stress tolerance is expected to have great poten... more The identification of leaf wax genes involved in stress tolerance is expected to have great potential for crop improvement. Here we report the characterization of a novel AP2 domain-containing putative transcription factor gene from the model legume Medicago truncatula. The gene, designated WXP1, is able to activate wax production and confer drought tolerance in alfalfa (Medicago sativa), the most important forage legume species in the world and a close relative of M. truncatula. The predicted protein of WXP1 has 371 aa; it is one of the longest peptides of all the single AP2 domain proteins in M. truncatula. WXP1 is distinctly different from the most studied genes in the AP2/ERF transcription factor family such as AP2s, CBF/DREB1s, DREB2s, WIN1/ SHN1 and GL15. Transcript level of WXP1 is inducible by cold, abscisic acid and drought treatment mainly in shoot tissues in M. truncatula. Overexpression of WXP1 under the control of the CaMV35S promoter led to a significant increase in cuticular wax loading on leaves of transgenic alfalfa. Scanning electron microscopy revealed earlier accumulation of wax crystals on the adaxial surface of newly expanded leaves and higher densities of wax crystalline structures on both adaxial and abaxial surfaces of mature leaves. Gas chromatography-mass spectrometry analysis revealed that total leaf wax accumulation per surface area increased 29.6-37.7% in the transgenic lines, and the increase was mainly contributed by C30 primary alcohol. WXP1 overexpression induced a number of wax-related genes. Transgenic leaves showed reduced water loss and chlorophyll leaching. Transgenic alfalfa plants with increased cuticular waxes showed enhanced drought tolerance demonstrated by delayed wilting after watering was ceased and quicker and better recovery when the dehydrated plants were re-watered.

Plant Molecular Biology, 2007

Cuticular waxes are the major components of plant cuticle and play an important role in protectin... more Cuticular waxes are the major components of plant cuticle and play an important role in protecting aerial organs from damage caused by biotic and abiotic stresses. Here we report the functional characterization of two putative ERF transcription factor genes WXP1 and its paralog WXP2 from Medicago truncatula. Transgenic expression of WXP1 and WXP2 in Arabidopsis (ecotype Columbia) led to significantly increased cuticular wax deposition on leaves of 4-week-old and 6-week-old transgenic plants, assessed based on fresh weight or based on surface area. Differences in the accumulation of various wax components as well as their chain length distributions were found in the WXP1 and WXP2 plants. The major wax component in Arabidopsis, n-alkanes, increased substantially in both WXP1 and WXP2 transgenics, however, another wax component, primary alcohols, increased in WXP1 plants but decreased in WXP2 plants. Cuticle properties of the transgenic leaves were analyzed by chlorophyll leaching assay; while the WXP1 plants had no change, the WXP2 plants showed more chlorophyll leaching. Analysis of fresh weight loss from detached leaves revealed that the transgenic leaves tend to retain more water than the control. Both WXP1 and WXP2 transgenic plants showed significantly enhanced whole plant drought tolerance. Analysis of freezing tolerance at the whole plant level and measurement of electrolyte leakage from detached leaves revealed that the WXP1 plants had increased freezing tolerance while the WXP2 plants were more sensitive to low temperature when compared to the control. Transgenic expression of WXP1 had no obvious effects on plant growth and development, however, the expression of WXP2 led to slower plant growth. These results indicate that WXP1 is a useful candidate gene for improving plant drought and freezing tolerance by genetic transformation.

Plant Biotechnology Journal, 2012

Re-use of this article is permitted in accordance with the Terms and Conditions set out at http:/... more Re-use of this article is permitted in accordance with the Terms and Conditions set out at http://wileyonlinelibrary.com/ onlineopen#OnlineOpen_Terms Keywords: biofuel crop, biomass, miR156, microRNA, Panicum virgatum, transgenic switchgrass.

Journal of Magnetism and Magnetic Materials, 2007

In this study, composite magnetic microspheres have been synthesized based on artemisia seed gum ... more In this study, composite magnetic microspheres have been synthesized based on artemisia seed gum and chitosan using the suspension cross-linking technique for use in the application of magnetic carrier technology. The properties of the composite magnetic microsperes, such as morphological, magnetic properties, thermal stability and the functional groups of the microspheres, were characterized by different techniques (i.e. SEM, magnetometry, DSC

Biotechnology and Sustainable Agriculture 2006 and Beyond, 2007

ABSTRACT Forages play a unique role in agriculture and the environment; they contribute through a... more ABSTRACT Forages play a unique role in agriculture and the environment; they contribute through animals to our food supply. Genetic improvement is one of the most effective ways to improve forage productivity. The potential of biotechnology in the development of improved forage grass cultivars has been recognized in recent years. Transgenic approaches are expected to complement or accelerate conventional breeding, since they offer the opportunity to generate unique genetic variation that would otherwise be absent or low in heritability. We have been interested in developing biotechnological methods to improve a number of important forage grass and legume species, such as tall fescue (Festuca arundinacea), bermudagrass (Cynodon dactylon), switchgrass (Panicum virgatum), alfalfa (Medicago samarizes our work in the following aspects: establishment of efficient genetic transformation systems for different forage species, cloning tion of transgenic forage plants with improved agronomic characteristics. tiva) and white clover (Trifolium repens). This report briefly sum- of potentially useful agronomical genes and promoters, and genera- tion of transgenic forage plants with improved agronomic characteristics.

Molecular Breeding of Forage and Turf, 2009

We have established genetic transformation systems for a number of important forage species inclu... more We have established genetic transformation systems for a number of important forage species including tall fescue, switchgrass, bermudagrass, zoysiagrass, alfalfa, white clover and Medicago truncatula. The target agronomic traits are forage quality, drought tolerance and phosphate uptake. This chapter summarizes our efforts in improving major forage grasses and legumes by transgenic approaches.

The Plant Journal, 2013

Switchgrass (Panicum virgatum L.) is a perennial C4 grass with the potential to become a major bi... more Switchgrass (Panicum virgatum L.) is a perennial C4 grass with the potential to become a major bioenergy crop. To help realize this potential, a set of RNA-based resources were developed. Expressed sequence tags (ESTs) were generated from two tetraploid switchgrass genotypes, Alamo AP13 and Summer VS16. Over 11.5 million high-quality ESTs were generated with 454 sequencing technology, and an additional 169 079 Sanger sequences were obtained from the 5' and 3' ends of 93 312 clones from normalized, full-length-enriched cDNA libraries. AP13 and VS16 ESTs were assembled into 77 854 and 30 524 unique transcripts (unitranscripts), respectively, using the Newbler and pave programs. Published Sanger-ESTs (544 225) from Alamo, Kanlow, and 15 other cultivars were integrated with the AP13 and VS16 assemblies to create a universal switchgrass gene index (PviUT1.2) with 128 058 unitranscripts, which were annotated for function. An Affymetrix cDNA microarray chip (Pvi_cDNAa520831) containing 122 973 probe sets was designed from PviUT1.2 sequences, and used to develop a Gene Expression Atlas for switchgrass (PviGEA). The PviGEA contains quantitative transcript data for all major organ systems of switchgrass throughout development. We developed a web server that enables flexible, multifaceted analyses of PviGEA transcript data. The PviGEA was used to identify representatives of all known genes in the phenylpropanoid-monolignol biosynthesis pathway.

Small, 2012

Dimension-and shape-tunable nanoarchitectures have attracted rapidly growing interest due to thei... more Dimension-and shape-tunable nanoarchitectures have attracted rapidly growing interest due to their structuredependent properties and important technological applications in the past few decades. [ 1 , 2 ] The manipulation of nanomaterials with specifi c structures possessing exceptional physics and chemical properties, via conveniently modulating the synthetic conditions, is one of the challenging issues in materials science. Recently, much attention has been paid to shape-and size-controlled synthesis of metal oxide nanostructures (e.g., rare earth compounds and transition metal oxides ) with unique performances.

PLoS ONE, 2012

Background: Switchgrass (Panicum virgatum L.) is a prime candidate crop for biofuel feedstock pro... more Background: Switchgrass (Panicum virgatum L.) is a prime candidate crop for biofuel feedstock production in the United States. As it is a self-incompatible polyploid perennial species, breeding elite and stable switchgrass cultivars with traditional breeding methods is very challenging. Translational genomics may contribute significantly to the genetic improvement of switchgrass, especially for the incorporation of elite traits that are absent in natural switchgrass populations.

International Journal of Plant Sciences, 2009

WXP1 is an ethylene-responsive element-binding transcription factor that has been shown to lead t... more WXP1 is an ethylene-responsive element-binding transcription factor that has been shown to lead to improved drought tolerance and increased wax accumulation when overexpressed in transgenic alfalfa under the control of the CaMV35S promoter. In this study, alfalfa was transformed with the WXP1 gene, driven by the epidermisspecific promoter CER6. The transgenic CER6::WXP1 alfalfa plants and a previously tested CaMV35S::WXP1 line were subjected to water stress for 3 d and then rewatered. Gas exchange, chlorophyll fluorescence, relative water content, and water potential were measured. Compared with the controls, the transgenic lines showed higher net photosynthetic rate, transpiration rate, and stomatal conductance and higher efficiency of photosystem II, quantum yield of photosystem II, coefficient of photochemical quenching, and apparent electron transport rate under water stress and after rewatering. The transgenic lines also showed higher relative water content and leaf water potential under water deficit conditions. The growth and development of CER6::WXP1 plants were normal, and the plants showed enhanced drought tolerance. Gas exchange and chlorophyll fluorescence data provided consistent evidence that the WXP1 transgenic lines experienced less damage under water stress conditions. This study revealed that increased wax accumulation did not have a negative impact on photosynthesis. The physiological analyses indicated that WXP1 is involved not only in wax biosynthesis but also in other physiological responses associated with enhanced drought tolerance that warrant further investigation.

International Journal of Plant Sciences, 2002

... Ji‐Yi Zhang,* Xiao‐Mei Li,* Richard R.‐C. Wang,2 , * A. Cortes,† V. Rosas,† and A. Mujeeb‐Kaz... more ... Ji‐Yi Zhang,* Xiao‐Mei Li,* Richard R.‐C. Wang,2 , * A. Cortes,† V. Rosas,† and A. Mujeeb‐Kazi† *USDA‐ARS, Forage and Range Research Laboratory, 695 North 1100 East, Logan, Utah 84322‐6300, USA; and †International Maize and Wheat Improvement Center (CIMMYT ...

Functional Plant Biology, 2010

White clover (Trifolium repens L.) is an important pasture legume in many regions of the world. A... more White clover (Trifolium repens L.) is an important pasture legume in many regions of the world. A commercial cultivar of white clover (cv. Patriot) was transformed with a Medicago truncatula L. transcription factor gene, WXP1, and a reporter gene, b-glucuronidase (GUS). The WXP1 gene and the GUS gene were placed under control of the Arabidopsis CER6 promoter. GUS staining and cross-section analysis revealed the CER6 promoter directed constitutive expression in leaves and epidermis preferential expression in petioles of white clover. Independent transgenic WXP1 lines, empty vector and wild-type controls were subjected to drought stress treatment. The plants were characterised by measuring several physiological parameters including gas exchange, chlorophyll fluorescence, relative water content and leaf water potential. The WXP1 transgenic lines had higher net photosynthetic rates, higher efficiency of PSII, higher relative water content and leaf water potential under drought-stressed conditions. Consistent with the results from physiological analyses, the transgenic white clover plants carrying WXP1 showed improved tolerance to drought stress.

BMC Plant Biology, 2008

Background: Tall fescue (Festuca arundinacea Schreb) is a major cool season forage and turf grass... more Background: Tall fescue (Festuca arundinacea Schreb) is a major cool season forage and turf grass species grown in the temperate regions of the world. In this paper we report the generation of a tall fescue expressed sequence tag (EST) database developed from nine cDNA libraries representing tissues from different plant organs, developmental stages, and abiotic stress factors. The results of inter-library and library-specific in silico expression analyses of these ESTs are also reported.

Plant, Cell & Environment, 2014

Medicago truncatula is a model legume forage crop native to the arid and semi-arid environments o... more Medicago truncatula is a model legume forage crop native to the arid and semi-arid environments of the Mediterranean. Given its drought-adapted nature, it is an ideal candidate to study the molecular and biochemical mechanisms conferring drought resistance in plants. Medicago plants were subjected to a progressive drought stress over 14 d of water withholding followed by rewatering under controlled environmental conditions. Based on physiological measurements of plant water status and changes in morphology, plants experienced mild, moderate and severe water stress before rehydration. Transcriptome analysis of roots and shoots from control, mildly, moderately and severely stressed, and rewatered plants, identified many thousands of genes that were altered in expression in response to drought. Many genes with expression tightly coupled to the plant water potential (i.e. drought intensity) were identified suggesting an involvement in Medicago drought adaptation responses. Metabolite profiling of drought-stressed plants revealed the presence of 135 polar and 165 non-polar compounds in roots and shoots. Combining Medicago metabolomic data with transcriptomic data yielded insight into the regulation of metabolic pathways operating under drought stress. Among the metabolites detected in drought-stressed Medicago plants, myo-inositol and proline had striking regulatory profiles indicating involvement in Medicago drought tolerance.

Frontiers in Plant Science, 2016

High biomass production and wide adaptation has made switchgrass (Panicum virgatum L.) an importa... more High biomass production and wide adaptation has made switchgrass (Panicum virgatum L.) an important candidate lignocellulosic bioenergy crop. One major limitation of this and other lignocellulosic feedstocks is the recalcitrance of complex carbohydrates to hydrolysis for conversion to biofuels. Lignin is the major contributor to recalcitrance as it limits the accessibility of cell wall carbohydrates to enzymatic breakdown into fermentable sugars. Therefore, genetic manipulation of the lignin biosynthesis pathway is one strategy to reduce recalcitrance. Here, we identified a switchgrass Knotted1 transcription factor, PvKN1, with the aim of genetically engineering switchgrass for reduced biomass recalcitrance for biofuel production. Gene expression of the endogenous PvKN1 gene was observed to be highest in young inflorescences and stems. Ectopic overexpression of PvKN1 in switchgrass altered growth, especially in early developmental stages. Transgenic lines had reduced expression of most lignin biosynthetic genes accompanied by a reduction in lignin content suggesting the involvement of PvKN1 in the broad regulation of the lignin biosynthesis pathway. Moreover, the reduced expression of the Gibberellin 20-oxidase (GA20ox) gene in tandem with the increased expression of Gibberellin 2-oxidase (GA2ox) genes in transgenic PvKN1 lines suggest that PvKN1 may exert regulatory effects via modulation of GA signaling. Furthermore, overexpression of PvKN1 altered the expression of cellulose and hemicellulose biosynthetic genes and increased sugar release efficiency in transgenic lines. Our results demonstrated that switchgrass PvKN1 is a putative ortholog of maize KN1 that is linked to plant lignification and cell wall and development traits as a major regulatory gene. Therefore, targeted overexpression of PvKN1 in bioenergy feedstocks may provide one feasible strategy for reducing biomass recalcitrance and simultaneously improving plant growth characteristics.

Forages play a key role in ruminant livestock production and environmental protection. Because fo... more Forages play a key role in ruminant livestock production and environmental protection. Because forage grasses and forage legumes often grow in marginal areas, stress tolerance is one of the most important traits in forage cultivar development. Conventional and genetic engineering approaches have been used to improve stress tolerance of forage grasses and legumes. This review summarizes recent advances in improving drought and salt tolerances of several major forage species

The Plant Journal, 2005

The identification of leaf wax genes involved in stress tolerance is expected to have great poten... more The identification of leaf wax genes involved in stress tolerance is expected to have great potential for crop improvement. Here we report the characterization of a novel AP2 domain-containing putative transcription factor gene from the model legume Medicago truncatula. The gene, designated WXP1, is able to activate wax production and confer drought tolerance in alfalfa (Medicago sativa), the most important forage legume species in the world and a close relative of M. truncatula. The predicted protein of WXP1 has 371 aa; it is one of the longest peptides of all the single AP2 domain proteins in M. truncatula. WXP1 is distinctly different from the most studied genes in the AP2/ERF transcription factor family such as AP2s, CBF/DREB1s, DREB2s, WIN1/ SHN1 and GL15. Transcript level of WXP1 is inducible by cold, abscisic acid and drought treatment mainly in shoot tissues in M. truncatula. Overexpression of WXP1 under the control of the CaMV35S promoter led to a significant increase in cuticular wax loading on leaves of transgenic alfalfa. Scanning electron microscopy revealed earlier accumulation of wax crystals on the adaxial surface of newly expanded leaves and higher densities of wax crystalline structures on both adaxial and abaxial surfaces of mature leaves. Gas chromatography-mass spectrometry analysis revealed that total leaf wax accumulation per surface area increased 29.6-37.7% in the transgenic lines, and the increase was mainly contributed by C30 primary alcohol. WXP1 overexpression induced a number of wax-related genes. Transgenic leaves showed reduced water loss and chlorophyll leaching. Transgenic alfalfa plants with increased cuticular waxes showed enhanced drought tolerance demonstrated by delayed wilting after watering was ceased and quicker and better recovery when the dehydrated plants were re-watered.

Plant Molecular Biology, 2007

Cuticular waxes are the major components of plant cuticle and play an important role in protectin... more Cuticular waxes are the major components of plant cuticle and play an important role in protecting aerial organs from damage caused by biotic and abiotic stresses. Here we report the functional characterization of two putative ERF transcription factor genes WXP1 and its paralog WXP2 from Medicago truncatula. Transgenic expression of WXP1 and WXP2 in Arabidopsis (ecotype Columbia) led to significantly increased cuticular wax deposition on leaves of 4-week-old and 6-week-old transgenic plants, assessed based on fresh weight or based on surface area. Differences in the accumulation of various wax components as well as their chain length distributions were found in the WXP1 and WXP2 plants. The major wax component in Arabidopsis, n-alkanes, increased substantially in both WXP1 and WXP2 transgenics, however, another wax component, primary alcohols, increased in WXP1 plants but decreased in WXP2 plants. Cuticle properties of the transgenic leaves were analyzed by chlorophyll leaching assay; while the WXP1 plants had no change, the WXP2 plants showed more chlorophyll leaching. Analysis of fresh weight loss from detached leaves revealed that the transgenic leaves tend to retain more water than the control. Both WXP1 and WXP2 transgenic plants showed significantly enhanced whole plant drought tolerance. Analysis of freezing tolerance at the whole plant level and measurement of electrolyte leakage from detached leaves revealed that the WXP1 plants had increased freezing tolerance while the WXP2 plants were more sensitive to low temperature when compared to the control. Transgenic expression of WXP1 had no obvious effects on plant growth and development, however, the expression of WXP2 led to slower plant growth. These results indicate that WXP1 is a useful candidate gene for improving plant drought and freezing tolerance by genetic transformation.

Plant Biotechnology Journal, 2012

Re-use of this article is permitted in accordance with the Terms and Conditions set out at http:/... more Re-use of this article is permitted in accordance with the Terms and Conditions set out at http://wileyonlinelibrary.com/ onlineopen#OnlineOpen_Terms Keywords: biofuel crop, biomass, miR156, microRNA, Panicum virgatum, transgenic switchgrass.

Journal of Magnetism and Magnetic Materials, 2007

In this study, composite magnetic microspheres have been synthesized based on artemisia seed gum ... more In this study, composite magnetic microspheres have been synthesized based on artemisia seed gum and chitosan using the suspension cross-linking technique for use in the application of magnetic carrier technology. The properties of the composite magnetic microsperes, such as morphological, magnetic properties, thermal stability and the functional groups of the microspheres, were characterized by different techniques (i.e. SEM, magnetometry, DSC

Biotechnology and Sustainable Agriculture 2006 and Beyond, 2007

ABSTRACT Forages play a unique role in agriculture and the environment; they contribute through a... more ABSTRACT Forages play a unique role in agriculture and the environment; they contribute through animals to our food supply. Genetic improvement is one of the most effective ways to improve forage productivity. The potential of biotechnology in the development of improved forage grass cultivars has been recognized in recent years. Transgenic approaches are expected to complement or accelerate conventional breeding, since they offer the opportunity to generate unique genetic variation that would otherwise be absent or low in heritability. We have been interested in developing biotechnological methods to improve a number of important forage grass and legume species, such as tall fescue (Festuca arundinacea), bermudagrass (Cynodon dactylon), switchgrass (Panicum virgatum), alfalfa (Medicago samarizes our work in the following aspects: establishment of efficient genetic transformation systems for different forage species, cloning tion of transgenic forage plants with improved agronomic characteristics. tiva) and white clover (Trifolium repens). This report briefly sum- of potentially useful agronomical genes and promoters, and genera- tion of transgenic forage plants with improved agronomic characteristics.

Molecular Breeding of Forage and Turf, 2009

We have established genetic transformation systems for a number of important forage species inclu... more We have established genetic transformation systems for a number of important forage species including tall fescue, switchgrass, bermudagrass, zoysiagrass, alfalfa, white clover and Medicago truncatula. The target agronomic traits are forage quality, drought tolerance and phosphate uptake. This chapter summarizes our efforts in improving major forage grasses and legumes by transgenic approaches.

The Plant Journal, 2013

Switchgrass (Panicum virgatum L.) is a perennial C4 grass with the potential to become a major bi... more Switchgrass (Panicum virgatum L.) is a perennial C4 grass with the potential to become a major bioenergy crop. To help realize this potential, a set of RNA-based resources were developed. Expressed sequence tags (ESTs) were generated from two tetraploid switchgrass genotypes, Alamo AP13 and Summer VS16. Over 11.5 million high-quality ESTs were generated with 454 sequencing technology, and an additional 169 079 Sanger sequences were obtained from the 5' and 3' ends of 93 312 clones from normalized, full-length-enriched cDNA libraries. AP13 and VS16 ESTs were assembled into 77 854 and 30 524 unique transcripts (unitranscripts), respectively, using the Newbler and pave programs. Published Sanger-ESTs (544 225) from Alamo, Kanlow, and 15 other cultivars were integrated with the AP13 and VS16 assemblies to create a universal switchgrass gene index (PviUT1.2) with 128 058 unitranscripts, which were annotated for function. An Affymetrix cDNA microarray chip (Pvi_cDNAa520831) containing 122 973 probe sets was designed from PviUT1.2 sequences, and used to develop a Gene Expression Atlas for switchgrass (PviGEA). The PviGEA contains quantitative transcript data for all major organ systems of switchgrass throughout development. We developed a web server that enables flexible, multifaceted analyses of PviGEA transcript data. The PviGEA was used to identify representatives of all known genes in the phenylpropanoid-monolignol biosynthesis pathway.

Small, 2012

Dimension-and shape-tunable nanoarchitectures have attracted rapidly growing interest due to thei... more Dimension-and shape-tunable nanoarchitectures have attracted rapidly growing interest due to their structuredependent properties and important technological applications in the past few decades. [ 1 , 2 ] The manipulation of nanomaterials with specifi c structures possessing exceptional physics and chemical properties, via conveniently modulating the synthetic conditions, is one of the challenging issues in materials science. Recently, much attention has been paid to shape-and size-controlled synthesis of metal oxide nanostructures (e.g., rare earth compounds and transition metal oxides ) with unique performances.

PLoS ONE, 2012

Background: Switchgrass (Panicum virgatum L.) is a prime candidate crop for biofuel feedstock pro... more Background: Switchgrass (Panicum virgatum L.) is a prime candidate crop for biofuel feedstock production in the United States. As it is a self-incompatible polyploid perennial species, breeding elite and stable switchgrass cultivars with traditional breeding methods is very challenging. Translational genomics may contribute significantly to the genetic improvement of switchgrass, especially for the incorporation of elite traits that are absent in natural switchgrass populations.

International Journal of Plant Sciences, 2009

WXP1 is an ethylene-responsive element-binding transcription factor that has been shown to lead t... more WXP1 is an ethylene-responsive element-binding transcription factor that has been shown to lead to improved drought tolerance and increased wax accumulation when overexpressed in transgenic alfalfa under the control of the CaMV35S promoter. In this study, alfalfa was transformed with the WXP1 gene, driven by the epidermisspecific promoter CER6. The transgenic CER6::WXP1 alfalfa plants and a previously tested CaMV35S::WXP1 line were subjected to water stress for 3 d and then rewatered. Gas exchange, chlorophyll fluorescence, relative water content, and water potential were measured. Compared with the controls, the transgenic lines showed higher net photosynthetic rate, transpiration rate, and stomatal conductance and higher efficiency of photosystem II, quantum yield of photosystem II, coefficient of photochemical quenching, and apparent electron transport rate under water stress and after rewatering. The transgenic lines also showed higher relative water content and leaf water potential under water deficit conditions. The growth and development of CER6::WXP1 plants were normal, and the plants showed enhanced drought tolerance. Gas exchange and chlorophyll fluorescence data provided consistent evidence that the WXP1 transgenic lines experienced less damage under water stress conditions. This study revealed that increased wax accumulation did not have a negative impact on photosynthesis. The physiological analyses indicated that WXP1 is involved not only in wax biosynthesis but also in other physiological responses associated with enhanced drought tolerance that warrant further investigation.

International Journal of Plant Sciences, 2002

... Ji‐Yi Zhang,* Xiao‐Mei Li,* Richard R.‐C. Wang,2 , * A. Cortes,† V. Rosas,† and A. Mujeeb‐Kaz... more ... Ji‐Yi Zhang,* Xiao‐Mei Li,* Richard R.‐C. Wang,2 , * A. Cortes,† V. Rosas,† and A. Mujeeb‐Kazi† *USDA‐ARS, Forage and Range Research Laboratory, 695 North 1100 East, Logan, Utah 84322‐6300, USA; and †International Maize and Wheat Improvement Center (CIMMYT ...

Functional Plant Biology, 2010

White clover (Trifolium repens L.) is an important pasture legume in many regions of the world. A... more White clover (Trifolium repens L.) is an important pasture legume in many regions of the world. A commercial cultivar of white clover (cv. Patriot) was transformed with a Medicago truncatula L. transcription factor gene, WXP1, and a reporter gene, b-glucuronidase (GUS). The WXP1 gene and the GUS gene were placed under control of the Arabidopsis CER6 promoter. GUS staining and cross-section analysis revealed the CER6 promoter directed constitutive expression in leaves and epidermis preferential expression in petioles of white clover. Independent transgenic WXP1 lines, empty vector and wild-type controls were subjected to drought stress treatment. The plants were characterised by measuring several physiological parameters including gas exchange, chlorophyll fluorescence, relative water content and leaf water potential. The WXP1 transgenic lines had higher net photosynthetic rates, higher efficiency of PSII, higher relative water content and leaf water potential under drought-stressed conditions. Consistent with the results from physiological analyses, the transgenic white clover plants carrying WXP1 showed improved tolerance to drought stress.

BMC Plant Biology, 2008

Background: Tall fescue (Festuca arundinacea Schreb) is a major cool season forage and turf grass... more Background: Tall fescue (Festuca arundinacea Schreb) is a major cool season forage and turf grass species grown in the temperate regions of the world. In this paper we report the generation of a tall fescue expressed sequence tag (EST) database developed from nine cDNA libraries representing tissues from different plant organs, developmental stages, and abiotic stress factors. The results of inter-library and library-specific in silico expression analyses of these ESTs are also reported.

Plant, Cell & Environment, 2014

Medicago truncatula is a model legume forage crop native to the arid and semi-arid environments o... more Medicago truncatula is a model legume forage crop native to the arid and semi-arid environments of the Mediterranean. Given its drought-adapted nature, it is an ideal candidate to study the molecular and biochemical mechanisms conferring drought resistance in plants. Medicago plants were subjected to a progressive drought stress over 14 d of water withholding followed by rewatering under controlled environmental conditions. Based on physiological measurements of plant water status and changes in morphology, plants experienced mild, moderate and severe water stress before rehydration. Transcriptome analysis of roots and shoots from control, mildly, moderately and severely stressed, and rewatered plants, identified many thousands of genes that were altered in expression in response to drought. Many genes with expression tightly coupled to the plant water potential (i.e. drought intensity) were identified suggesting an involvement in Medicago drought adaptation responses. Metabolite profiling of drought-stressed plants revealed the presence of 135 polar and 165 non-polar compounds in roots and shoots. Combining Medicago metabolomic data with transcriptomic data yielded insight into the regulation of metabolic pathways operating under drought stress. Among the metabolites detected in drought-stressed Medicago plants, myo-inositol and proline had striking regulatory profiles indicating involvement in Medicago drought tolerance.