Plants grown under stress conditions generate excessive reactive oxygen species resulting in cell death. Therefore, plants activate the protection mechanism via antioxidant accumulation. Anthocyanins are flavonoid-derived secondary metabolites with high antioxidant properties. In this study, we analyzed and characterized the promoter region of RsMYB1, a positive regulator of anthocyanin biosynthesis. The RsMYB1 promoter was designed with four different fragment lengths (MP1, -1034; MP2, -830; MP3, -633; and MP4, -430 bp), and then each RsMYB1 promoter region was fused into a GUS gene for Arabidopsis transformation. The expression patterns of the RsMYB1 promoter constructs were analyzed at different developmental stages and under various abiotic stresses. The GUS expression pattern steadily increased with plant growth, and coincided with enzyme activity and a histochemical GUS assay. In response to drought, salt, sucrose, and low temperature, the GUS transcript level was highly expressed in MP4 in parallel with GUS enzyme activity. These assays indicated that the proximal region (-430 to -1 bp) of RsMYB1 was the core sequence that was induced by salt and low temperature. The expression level of RsMYB1 in the leaves of radish was highly activated and was consistent with the anthocyanin content under salt and low temperature conditions. These results suggest that induction of the RsMYB1 gene can activate the biosynthesis of anthocyanins, which are expected to help plants adapt to stress conditions due to their antioxidant activity.

Chlorophyll is an essential pigment involved in light absorption and electron transfer in photosynthesis, a photochemical process that is indispensable for plant growth and development. The biosynthesis of chlorophyll occurs in plastids and shares a common biosynthetic pathway with other tetrapyrroles. The chlorophyll metabolic pathway is divided into four distinct components: the common pathway, chlorophyll-specific biosynthetic pathway, chlorophyll cycle, and chlorophyll degradation pathway, which are regulated in developmental- and environmental-specific manners. During the early stages of plant growth, the expression of most chlorophyll biosynthetic genes is induced by light, resulting in an increase in chlorophyll accumulation, induction of high photosynthetic activity, and continuous plant growth. In contrast, during plant maturation, the expression of most of these genes is gradually downregulated, whereas genes involved in chlorophyll degradation are upregulated during leaf senescence. Chlorophyll biosynthesis is directly or indirectly regulated by the members of various transcription factor families. In this review, we describe representative mechanisms of transcription factor-mediated activation and repression of chlorophyll biosynthesis in response to light treatment. We also present an overview of recent studies that have examined all the enzymatic steps involved in chlorophyll metabolic pathways and their gene regulation at the transcriptional level, which will enable readers to gain a better understanding of chlorophyll metabolism.

In recent years, new plant breeding technologies (NPBT) have had enormous effects on breeding and the agricultural industry. In particular, genome editing technology, including site-directed nuclease technologies, has progressed dramatically since the first-generation Zinc finger nucleases to the third-generation clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9). CRISPR/Cas9 technology has yielded a revolutionary breakthrough in the accurate, efficient, and user-friendly genome editing of eukaryotes. Several methods for basic research and applications, such as knock-out, base editing, gene targeting, and transcriptional activation or repression have been derived from CRISPR/Cas9 technology. Herein, we will describe the current progress in NPBTs and also summarize the crops developed by NPBTs. After analyzing the current status of NPBTs and crop development, we have proposed potential strategies for crop development using NPBTs.

In ornamental crops, the color and shape of flowers are one of the important traits. Generally, flower colors are determined by accumulating pigments such as carotenoids, flavonoids, and betalains. Among them, flavonoids are responsible for broad ranges of colors. Chrysanthemums are one of the most popular ornamental crops in the world, and there have been many efforts to change their flower color. In chrysanthemum flowers, cyanidin-based anthocyanin confers pink or red color, whereas terpenoid-based carotenoids are mainly responsible for yellow and green colors. However, blue colored chrysanthemums do not occur in nature. To date, there have been attempts to obtain blue or violet-colored chrysanthemum flowers through the introduction of a novel gene for accumulating delphinidin-based anthocyanins, while other studies have reported changing endogenous metabolites through the reconstruction of flavonoid biosynthesis. Since various transcription factors are involved in the regulation of flavonoid biosynthesis, it is important to understand not only the structural genes, but also the transcription factors required for the modification of flavonoid-based flower color. Therefore, in this paper, we describe the flavonoid biosynthetic pathway and its regulation, and review previous studies on the change in flower color through modification of flavonoid biosynthesis. This effort could be an important milestone in successfully achieving the modification of chrysanthemum flower color by means of plant biotechnology.

Promoters are essential regulatory elements for efficiently expressing a gene of interest in a target tissue of a organism. Therefore, the identification of a suitable promoter is important in plant biotechnology. In this study, four promoters were selected and identified to be constitutively or tissue-specifically expressed in Brassica rapa bacterial artificial chromosome (BAC) clones using the results of transcriptomic analysis of Brassica rapa and open-source database information on Arabidopsis thaliana. The 2 kb region of the 5′ upstream was isolated from the Brassica rapa genomic DNA for each promoter. The four promoters were then fused to β-glucuronidase (gus) and green fluorescent protein (gfp) genes, and the recombinant transgenes were introduced into Arabidopsis. As a result of histochemical GUS staining, GFP fluorescence and RT-PCR, the gus gene was observed to be expressed constitutively in all tissues using all four promoters. A GUS activity assay using fluorescent 4-MUG revealed that the BR11 promoter showed similar activity to the CaMV35S promoter, while the BR4, BR15, and BR16 promoters showed 1.5, 4, and 18-fold higher activities than the CaMV35S promoter, respectively. These results indicate that these four promoters could be used to incorporate useful genes with enhanced function into crops of interest.

Gliadin proteins are a major component of gluten proteins and important determinants of bread-making quality by conferring the viscosity and extensibility of dough, but also present significant health problems for consumers with wheat-related diseases like celiac disease or wheat allergies. In order to solve this problem, we conducted RP-HPLC analysis to profile gliadin fractions for screening the mutants deficient in gliadins from 122 wheat doubled-haploid (DH) lines cultivated by the National Institute of Crop Science. Comparing the RP-HPLC chromatogram of 122 DH lines with those of the respective parents, we found that some peaks of omega-5 gliadin were not present in 28 DH lines. Further analysis using SDS-PAGE and A-PAGE showed that the omega-5 gliadin in the parental varieties had two to three bands, but only one band in the absent 28 DH lines. The relative expression levels of all gliadin groups in the parental and mutant lines were also examined by RP-HPLC. Our study contributes to establishing a method for the rapid screening and identification of mutants missing gliadins as major epitopes of wheat-related disease in many wheat genetic resources and breeding lines as valuable information to other researchers.

Gliadin proteins, which are a component of gluten and confer viscosity and extensibility on wheat dough, are major determinants of wheat processing suitability and also present dietary problems for consumers with celiac disease or wheat allergies. In this study, gliadin proteins of the hexaploid wheat variety ‘Chinese Spring’ (CS) and of its nullisomic-tetrasomic (NT) and ditelosomic (DT) lines missing group 1 and 6 chromosome, were analyzed using LabChip GXII Touch 24 within 1 min per sample. The chromatogram pattern analysis of gliadin proteins from group 1 aneuploid lines (N1AT1B, N1AT1D; N1BT1A, N1BT1D; N1DT1A, N1DT1B) missing 1A, 1B and 1D chromosomes respectively, from CS showed that 24, 25 and 26 sec peaks of CS, presuming to be ω5-, ω1,2- and γ- gliadins, were disappeared. The analysis of group 6 aneuploid lines (N6AT6B, N6AT6D, 6AL; N6BT6A, 6BL; N6DT6B, 6DL) missing 6A, 6AS; 6B, 6BS; 6D, 6DS chromosomes respectively, from CS indicated that 22, 25 and 26 sec peaks of CS, presuming to be α-/β- gliadins, were disappeared. The results of this study will be applicable to high-throughput screening of wheat gliadin mutants among wheat breeding lines and genetic resources for the development of allergy - reduced wheat.

To identify and apply tissue-specific promoters is one of the major challenges in plants genetic engineering for optimizing efficient expression of interest genes in appropriate tissues. In this research, open-source database information of Arabidopsis thaliana was adapted to determine root-specific expressed promoter region. A total seven sequences that might function as a root-specific promoter element were initially isolated from Arabidopsis genomic DNA. Then seven promoters were cloned into pBGWFS7 in which β-glucuronidase (gus) and green fluorescent protein (gfp) genes were linked. The GUS activities were measured in different tissues of transgenic Arabidopsis by both histochemical GUS staining and fluorescent 4 methylumbelliferyl β-D-glucuronide (MUG) assay. To confirm root-specific expression, GFP-confocal microscope analysis was conducted in Arabidopsis transgenic plant. As a result, the five promoters showed strong GUS activity in the root tissue as compared with the CaMV35S promoter. To test crop application availability as a root-specific promoter, seven promoters were introduced into tomato plants and confirmed transient expression using Agrobacterium rhizogenesis ARqua1 root-nodule inducible strain. Two promoters showed that gus genes were specifically expressed in roots of transgenic tomato plant. Taken together, the novel seven promoters showed specific activity in root suggesting that it is applicable in crop improvement.

APETALA2/ethylene response factor (AP2/ERF) transcription factors are involved in biological and abiotic stress response, plant development, and growth. AP2/ERF genes are classified into five families (AP2, DREB, ERF, RAV, and soloist), and most genes belong to DREB and ERF families. So far, genomic analysis of DREB and ERF family genes of various plant species has been performed, and classifications based on the homology of AP2/ERF-specific DNA binding domain, arrangement of exons and introns, and similarity of group-specific conserved motifs have been conducted. These classifications provide plausible information for the prediction of AP2/ERF gene function. In this paper, an overview of the classification, structure, evolution, and function of AP2/ERF genes is described, and the functional properties and regulatory mechanisms of ERF family genes that have been identified are summarized by group according to the functional classification of Arabidopsis ERF family genes. This shows that group-specific conserved motifs of Arabidopsis ERF family genes are closely linked with group-specific functions and regulatory mechanisms, indicating that the effective functional prediction of ERF family genes through such a classification scheme can be usefully applied to the trait improvements of various plants.

The ω5-gliadins are the major allergens in wheat-dependent excise-induced anaphylaxis (WDEIA). In this study, SDS-PAGE analysis was used to assign the ω5-gliadins (Gli-B1) alleles in thirty two Korean wheat cultivars, compared with eleven standard wheat cultivars for Gli-B1a~m alleles. These results were reconfirmed with their complementary Glu-B3 low-molecular-weight glutenin subunits alleles tightly linked with Gli-B1 locus revealed with 2-DGE in our previous study. As a result, one Gli-B1b, four Gli-B1d, two Gli-B1f, six Gli-B1m and nineteen Gli-B1h varieties were identified. This is the first report on revealing the Gli-B1 alleles in Korean wheat cultivars and represents valuable basic data on wheat allergy, relationship between gliadin and wheat quality, and development of hypo-allergenic wheat.

Low-molecular-weight glutenin subunits (LMW-GS) play a crucial role in the processing quality of wheat flour. They are encoded multi gene family located at the Glu-A3, Glu-B3 and Glu-D3 on the short arm of chromosome 1A, 1B and 1D respectively. Typical LMW-GSs are composed of three parts including a short N-terminal domain, a relatively short repetitive domain and a C-terminal domain. Further, typical LMW-GS sequences are divided into LMW-s, LMW-m and LMW-i types, on the basis of the first amino acid of the mature proteins (serine, methionine and isoleucine, respectively). Although it is known that the allelic variation of LMW-GSs affect the properties of dough, it is still not clear which LMW-GSs confer better bread-making quality because of the larger number of expressed subunits and their overlapping mobility with abundant gliadin proteins. Therefore, it is important to characterize LMW-GS genes and develop functional markers to identify different LMW-GS alleles for application in wheat breeding. In this review, we discuss the various aspects of LMW-GS, including their structural characteristics, the development of marker, relationship between LMW-GSs and bread wheat quality, and genetic engineering of the LMW-GSs.