Sunjung Park - Academia.edu (original) (raw)

Papers by Sunjung Park

This project would not be completed without the support and believes of many people. I wish to th... more This project would not be completed without the support and believes of many people. I wish to thank my major professor, Dr. Zhi-Yuan Chen for valuable advice, guidance and encouragement. He guided me to become a good scientist with an incredible patience. I received thoughtful suggestions and warm spiritual support for a long time from the committee members as well as from all the people of Department of Plant Pathology and Crop Physiology.

Industrial Crops and Products, 2017

Camelina sativa is an old world crop newly introduced to the semi-arid regions of the Southwester... more Camelina sativa is an old world crop newly introduced to the semi-arid regions of the Southwestern US. Recently, Camelina gained attention as a biofuel feedstock crop due to its relatively high oil content, polyunsaturated fatty acids, very short growing season with fairly good adaption to marginal lands, and low input agricultural systems. To expand Camelina growing zones into more arid regions, it is important to develop new drought resistant cultivars that can grow under water-limited conditions. Plants having cuticles with low permeability to water can possess elevated dehydration avoidance and improved drought tolerance. To extend our understating of cuticle chemical composition among Camelina species, leaf wax and cutin monomers in seventeen accessions representing four Camelina species were analyzed. Camelina exhibited a wide range of wax and cutin contents. The primary alcohols and alkanes were the predominant classes of leaf wax, followed in abundance by wax esters, fatty acids, aldehydes, alkylguaiacols, methylalkylresorcinols, α-amyrin and ß-sitosterol. Among primary alcohols, the dominant constituents were the C 24 , C 26 and C 28 homologues, while the C 31 homologue was the most abundant alkane among all Camelina accessions. Cutin monomers included monohydroxy monobasic acids, phenolics, monobasic acids, monohydroxy epoxymonobasic acids, and dibasic acids. Among the cutin monomers examined, the C 16:0 diOH acid showed extensive variation among Camelina species.

ELECTROPHORESIS, 2008

A high peak capacity 2-D protein separation system combining SDS micro-CGE (SDS m-CGE) with micro... more A high peak capacity 2-D protein separation system combining SDS micro-CGE (SDS m-CGE) with microchip MEKC (m-MEKC) using a PMMA microfluidic is reported. The utility of the 2-D microchip was demonstrated by generating a 2-D map from a complex biological sample containing a large number of constituent proteins using fetal calf serum (FCS) as the model system. The proteins were labeled with a thiol-reactive AlexaFluor 633 fluorophore (excitation/emission: 633/652 nm) to allow for ultra-sensitive on-chip detection using LIF following the 2-D separation. The high-resolution separation of the proteins was accomplished based on their size in the SDS m-CGE dimension and their interaction with micelles in the m-MEKC dimension. A comprehensive 2-D SDS m-CGE Â m-MEKC separation of the FCS proteins was completed in less than o30 min using this 2-D microchip format, which consisted of 60 mm and 50 mm effective separation lengths for the first and second separation dimensions, respectively. Results obtained from the microchip separation were compared with protein maps acquired using conventional 2-D IEF and SDS-PAGE of a similar FCS sample. The microchip 2-D separation was found to be $60 Â faster and yielded an average peak capacity of 2600 (7149), nearly three times larger than that obtained using conventional IEF/SDS-PAGE.

American Journal of Plant Sciences, 2012

The importance of controlled temperature during the four-days co-cultivation period was evaluated... more The importance of controlled temperature during the four-days co-cultivation period was evaluated under the most physiologically relevant conditions for Agrobacterium tumefaciens-mediated transformation of tobacco (Nicotiana tabacum L. cv. Xanthi (nn, Smith)) leaf disks. We compared the effect of temperatures ranging from 15˚C, 18˚C, 20˚C, 22˚C to 25˚C on the stable expression of β-glucuronidase (GUS) activity of 14 days old hygromycin-selected leaf disks, and on the increase in the fresh weight yield of 28 days old kanamycin-selected calli. The highest average of GUS activity was obtained at 20˚C among the five temperatures tested although the difference between the 18˚C and 20˚C treatment was not statistically significant. The GUS activity at 15˚C was statistically lower than those at 18˚C and 20˚C. The GUS activity in 22˚C treatment was an intermediate between the highest (18/20˚C) and second highest averages (15˚C), and was not statistically significantly different. The lowest average of GUS activity was observed at 25˚C. The highest increase in the plate average of fresh weight yield was obtained at 20˚C among the five temperature tested. The 20˚C treatment was statistically significantly better than the 15˚C and 18˚C treatments. The 20˚C co-cultivation treatment resulted in the higher FW yield than 22˚C and 25˚C even though the differences were not statistically significant. In conclusion, low co-cultivation temperature at 20˚C resulted in the reproducible maximum increase in both the fresh weight yield and stable expression of GUS activity after transformation of tobacco leaf disks.

....vii Chapter 1. Introduction .......... more ....vii Chapter 1. Introduction .......1 Chapter 2. Review of Literature ..... 3 2.1 Molecular Mechanism of Agrobacterium-mediated DNA Transfer ...........3 2.2 Adoption for Plant Molecular Biology ....10 2.3 Agrobacterium-mediated Plant Transformation Protocol Development ....12 Chapter 3. Materials and Methods ............20 3.1 Materials ...20 3.2 Methods ....22 Chapter 4. Results ...........27 4.1 Effect of Temperature During the Co-cultivation ..........27 4.2 Comparison of Two β-glucuronidase Genes ................28 4.3 Effect of Surfactant, Vacuum Pressure Strength and Duration .....32 4.4 Effect of Co-cultivation Durations and Bacteria Concentrations .............39 4.5 Effect of Bacterial Pre-culture Conditions and Acetosyringone Concentrations .39 4....

The Plant journal : for cell and molecular biology, 2017

Cytoplasmic lipid droplets (LDs) are found in all types of plant cells; they are derived from the... more Cytoplasmic lipid droplets (LDs) are found in all types of plant cells; they are derived from the endoplasmic reticulum and function as a repository for neutral lipids, as well as serving in lipid remodelling and signalling. However, the mechanisms underlying the formation, steady-state maintenance and turnover of plant LDs, particularly in non-seed tissues, are relatively unknown. Previously, we showed that the LD-associated proteins (LDAPs) are a family of plant-specific, LD surface-associated coat proteins that are required for proper biogenesis of LDs and neutral lipid homeostasis in vegetative tissues. Here, we screened a yeast two-hybrid library using the Arabidopsis LDAP3 isoform as 'bait' in an effort to identify other novel LD protein constituents. One of the candidate LDAP3-interacting proteins was Arabidopsis At5g16550, which is a plant-specific protein of unknown function that we termed LDIP (LDAP-interacting protein). Using a combination of biochemical and cellu...

Genetic Engineering - An Insight into the Strategies and Applications, 2016

Agrobacterium tumefaciens, a plant pathogen, is commonly used as a vector for the introduction of... more Agrobacterium tumefaciens, a plant pathogen, is commonly used as a vector for the introduction of foreign genes into plants and consequent regeneration of transgenic plants. A. tumefaciens naturally infects the wound sites in dicotyledonous plants and induces diseases known as crown gall. The bacterium has a large plasmid that induces tumor induction, and for this reason, it was named tumor-inducing (Ti) plasmid. The expression of T-DNA genes of Ti-plasmid in plant cells causes the formation of tumors at the infection site. The molecular basis of Agrobacterium-mediated transformation is the stable integration of a DNA sequence (T-DNA) from Ti (tumor-inducing) plasmid of A. tumefaciens into the plant genome. A. tumefaciens-mediated transformation has some advantages compared with direct gene transfer methods such as integration of low copy number of T-DNA into plant genome, stable gene expression, and transformation of large size DNA segments. That is why manipulations of the plant, bacteria and physical conditions have been applied to increase the virulence of bacteria and to increase the transformation efficiency. Preculturing explants before inoculation, modification of temperature and medium pH, addition chemicals to inoculation medium such as acetosyringone, changing bacterial density, and cocultivation period, and vacuum infiltration have been reported to increase transformation. In this chapter, four new transformation protocols that can be used to increase the transformation efficiency via A. tumefaciens in most plant species are described.

Plant biotechnology journal, Jan 17, 2016

Fat storage-inducing transmembrane protein 2 (FIT2) is an endoplasmic reticulum (ER)-localized pr... more Fat storage-inducing transmembrane protein 2 (FIT2) is an endoplasmic reticulum (ER)-localized protein that plays an important role in lipid droplet (LD) formation in animal cells. However, no obvious homologue of FIT2 is found in plants. Here, we tested the function of FIT2 in plant cells by ectopically expressing mouse (Mus musculus) FIT2 in Nicotiana tabacum suspension-cultured cells, N. benthamiana leaves, and Arabidopsis thaliana plants. Confocal microscopy indicated that the expression of FIT2 dramatically increased the number and size of LDs in leaves of N. benthamiana and Arabidopsis, and lipidomics analysis and mass spectrometry imaging confirmed the accumulation of neutral lipids in leaves. FIT2 also increased seed oil content by ~13% in some stable, overexpressing lines of Arabidopsis. When expressed transiently in leaves of N. benthamiana or suspension cells of N. tabacum, FIT2 localized specifically to the ER, and was often concentrated at certain regions of the ER that...

The Faseb Journal, Apr 1, 2012

Plant physiology, Apr 19, 2016

Eukaryotic cells compartmentalize neutral lipids into organelles called lipid droplets (LDs), and... more Eukaryotic cells compartmentalize neutral lipids into organelles called lipid droplets (LDs), and while much is known about the role of LDs in storing triacylglycerols (TAGs) in seeds, their biogenesis and function in non-seed tissues is poorly understood. Recently, we identified a class of plant-specific, LD-associated proteins (LDAPs) that are abundant components of LDs in non-seed cell types. Here, we characterized the three LDAPs in Arabidopsis thaliana to gain insight to their targeting, assembly and influence on LD function and dynamics. While all three LDAPs targeted specifically to the LD surface, truncation analysis of LDAP3 revealed that essentially the entire protein was required for LD localization. The association of LDAP3 with LDs was detergent-sensitive, but the protein bound with similar affinity to synthetic liposomes of various phospholipid compositions, suggesting that other factors contributed to targeting specificity. Investigation of LD dynamics in leaves revea...

BMC Plant Biology, 2014

Background: The majority of commercial cotton varieties planted worldwide are derived from Gossyp... more Background: The majority of commercial cotton varieties planted worldwide are derived from Gossypium hirsutum, which is a naturally occurring allotetraploid produced by interspecific hybridization of A-and D-genome diploid progenitor species. While most cotton species are adapted to warm, semi-arid tropical and subtropical regions, and thus perform well in these geographical areas, cotton seedlings are sensitive to cold temperature, which can significantly reduce crop yields. One of the common biochemical responses of plants to cold temperatures is an increase in omega-3 fatty acids, which protects cellular function by maintaining membrane integrity. The purpose of our study was to identify and characterize the omega-3 fatty acid desaturase (FAD) gene family in G. hirsutum, with an emphasis on identifying omega-3 FADs involved in cold temperature adaptation. Results: Eleven omega-3 FAD genes were identified in G. hirsutum, and characterization of the gene family in extant A and D diploid species (G. herbaceum and G. raimondii, respectively) allowed for unambiguous genome assignment of all homoeologs in tetraploid G. hirsutum. The omega-3 FAD family of cotton includes five distinct genes, two of which encode endoplasmic reticulum-type enzymes (FAD3-1 and FAD3-2) and three that encode chloroplast-type enzymes (FAD7/8-1, FAD7/8-2, and FAD7/8-3). The FAD3-2 gene was duplicated in the A genome progenitor species after the evolutionary split from the D progenitor, but before the interspecific hybridization event that gave rise to modern tetraploid cotton. RNA-seq analysis revealed conserved, gene-specific expression patterns in various organs and cell types and semi-quantitative RT-PCR further revealed that FAD7/8-1 was specifically induced during cold temperature treatment of G. hirsutum seedlings. Conclusions: The omega-3 FAD gene family in cotton was characterized at the genome-wide level in three species, showing relatively ancient establishment of the gene family prior to the split of A and D diploid progenitor species. The FAD genes are differentially expressed in various organs and cell types, including fiber, and expression of the FAD7/8-1 gene was induced by cold temperature. Collectively, these data define the genetic and functional genomic properties of this important gene family in cotton and provide a foundation for future efforts to improve cotton abiotic stress tolerance through molecular breeding approaches.

The Plant Cell, 2013

COMPARATIVE GENE IDENTIFICATION-58 (CGI-58) is a key regulator of lipid metabolism and signaling ... more COMPARATIVE GENE IDENTIFICATION-58 (CGI-58) is a key regulator of lipid metabolism and signaling in mammals, but its underlying mechanisms are unclear. Disruption of CGI-58 in either mammals or plants results in a significant increase in triacylglycerol (TAG), suggesting that CGI-58 activity is evolutionarily conserved. However, plants lack proteins that are important for CGI-58 activity in mammals. Here, we demonstrate that CGI-58 functions by interacting with the PEROXISOMAL ABC-TRANSPORTER1 (PXA1), a protein that transports a variety of substrates into peroxisomes for their subsequent metabolism by β-oxidation, including fatty acids and lipophilic hormone precursors of the jasmonate and auxin biosynthetic pathways. We also show that mutant cgi-58 plants display changes in jasmonate biosynthesis, auxin signaling, and lipid metabolism consistent with reduced PXA1 activity in planta and that, based on the double mutant cgi-58 pxa1, PXA1 is epistatic to CGI-58 in all of these process...

Plant Signaling & Behavior, 2014