Development of stress-tolerant transgenic plants via RNA metabolism control

Hunseung Kang,Tao Xu,Lili Gu,Min Kyung Kim,Su Jung Park 한국육종학회 2013 한국육종학회 심포지엄 Vol.2013 No.07

Environmental stresses including drought, extreme temperatures, and high salinity are major factors that severely limit crop productivity worldwide. To overcome yield loss due to these environmental stresses, a large number of researches have been conducted to understand how plants respond to and adapt these environmental stresses. Posttranscriptional regulation as well as transcriptional regulation of gene expression is recognized as a key regulatory process in plant stress responses, and these cellular processes are regulated by diverse RNA-binding proteins (RBPs). Over the last years, we have extensively investigated the functional roles of RBPs that harbor an RNA-recognition motif at the N-terminal half and a glycine-rich region at the C-terminal half (glycine-rich RNA-binding proteins, GRPs), zinc finger-containing GRP, and cold shock domain proteins (CSDPs) in Arabidopsis thaliana, rice (Oryza sativa), wheat (Triticum aestivum), and rapeseed (Brasicca napus) under stress conditions. Our comparative analysis demonstrated that certain family members display RNA chaperone function during stress adaptation process in monocotyledonous plants as well as in dicotyledonous plants. These findings point to the importance of the regulation of mRNA metabolism in plant response to environmental stresses and shed new light on the practical application of these RBPs to develop stress-tolerant transgenic crops.

Emerging Roles of RNA-Binding Proteins in Plant Growth, Development, and Stress Responses

Lee, Kwanuk,Kang, Hunseung Korean Society for Molecular and Cellular Biology 2016 Molecules and cells Vol.39 No.3

Posttranscriptional regulation of RNA metabolism, including RNA processing, intron splicing, editing, RNA export, and decay, is increasingly regarded as an essential step for fine-tuning the regulation of gene expression in eukaryotes. RNA-binding proteins (RBPs) are central regulatory factors controlling posttranscriptional RNA metabolism during plant growth, development, and stress responses. Although functional roles of diverse RBPs in living organisms have been determined during the last decades, our understanding of the functional roles of RBPs in plants is lagging far behind our understanding of those in other organisms, including animals, bacteria, and viruses. However, recent functional analysis of multiple RBP family members involved in plant RNA metabolism and elucidation of the mechanistic roles of RBPs shed light on the cellular roles of diverse RBPs in growth, development, and stress responses of plants. In this review, we will discuss recent studies demonstrating the emerging roles of multiple RBP family members that play essential roles in RNA metabolism during plant growth, development, and stress responses.

The Role of a Zinc Finger-containing Glycine-rich RNA-binding Protein During the Cold Adaptation Process in Arabidopsis thaliana

Kim, Yeon-Ok,Kang, Hunseung Oxford University Press 2006 Plant & cell physiology Vol.47 No.6

<P>The mechanistic role of a glycine-rich RNA-binding protein designated atRZ-1a that contributes to enhance cold tolerance in <I>Arabidopsis</I> was investigated. Overexpression of atRZ-1a did not affect the expression of various cold-responsive genes such as COR6.6, COR15a, COR47, RD29A, RD29B and LTI29. Proteome analyses revealed that overexpression of atRZ-1a modulated the expression of several stress-responsive genes, and the transcript levels and RNA stability of these target genes were not affected by atRZ-1a. atRZ-1a successfully complements the cold sensitivity of <I>Escherichia coli</I> lacking four cold shock proteins. These results strongly suggest that atRZ-1a plays a role as an RNA chaperone during the cold adaptation process.</P>

Comparative expression analysis of genes encoding metallothioneins in response to heavy metals and abiotic stresses in rice (<i>Oryza sativa</i>) and <i>Arabidopsis thaliana</i>

Kim, Yeon-Ok,Kang, Hunseung Informa UK (TaylorFrancis) 2018 Bioscience, biotechnology, and biochemistry Vol.82 No.9

<P>To get insights into the functions of metallothionein (MT) in plant response to multiple stresses, expressions of 10 rice MT genes (OsMTs) and 7 Arabidopsis MT genes (AtMTs) were comprehensively analyzed under combined heavy metal and salt stress. OsMT1a, OsMT1b, OsMT1c, OsMT1g, and OsMT2a were increased by different heavy metals. Notably, ABA remarkably increased OsMT4 up to 80-fold. Combined salt and heavy metals (Cd, Pb, Cu) synergistically increased OsMT1a, OsMT1c, and OsMT1g, whereas combined salt and H2O2 or ABA synergistically increased OsMT1a and OsMT4. Heavy metals decreased AtMT1c, AtMT2b, and AtMT3 but cold or ABA increased AtMT1a, AtMT1c, and AtMT2a. AtMT4a was markedly increased by salt stress. Combined salt and other stresses (Pb, Cd, H2O2) synergistically increased AtMT4a. Taken together, these findings suggest that MTs in monocot and dicot respond differently to combined stresses, which provides a valuable basis to further determine the roles of MTs in broad stress tolerance.</P>

S1 domain‐containing STF modulates plastid transcription and chloroplast biogenesis in <i>Nicotiana benthamiana</i>

Jeon, Young,Jung, Hyun Ju,Kang, Hunseung,Park, Youn‐,Il,Lee, Soon Hee,Pai, Hyun‐,Sook Blackwell Publishing Ltd 2012 The New phytologist Vol.193 No.2

<P><B>Summary</B></P><P><P>In this study, we examined the biochemical and physiological functions of <I>Nicotiana benthamiana</I> S1 domain‐containing Transcription‐Stimulating Factor (STF) using virus‐induced gene silencing (VIGS), cosuppression, and overexpression strategies.</P><P>STF : green fluorescent protein (GFP) fusion protein colocalized with sulfite reductase (SiR), a chloroplast nucleoid‐associated protein also present in the stroma. Full‐length STF and its S1 domain preferentially bound to RNA, probably in a sequence‐nonspecific manner.</P><P><I>STF</I> silencing by VIGS or cosuppression resulted in severe leaf yellowing caused by disrupted chloroplast development. STF deficiency significantly perturbed plastid‐encoded multimeric RNA polymerase (PEP)‐dependent transcript accumulation. Chloroplast transcription run‐on assays revealed that the transcription rate of PEP‐dependent plastid genes was reduced in the <I>STF</I>‐silenced leaves. Conversely, the exogenously added recombinant STF protein increased the transcription rate, suggesting a direct role of STF in plastid transcription. Etiolated seedlings of <I>STF</I> cosuppression lines showed defects in the light‐triggered transition from etioplasts to chloroplasts, accompanied by reduced light‐induced expression of plastid‐encoded genes.</P><P>These results suggest that STF plays a critical role as an auxiliary factor of the PEP transcription complex in the regulation of plastid transcription and chloroplast biogenesis in higher plants.</P></P>

Cold-inducible zinc finger-containing glycine-rich RNA-binding protein contributes to the enhancement of freezing tolerance in <i>Arabidopsis thaliana</i>

Kim, Yeon-Ok,Kim, Jin Sun,Kang, Hunseung Blackwell Science Ltd 2005 The Plant journal Vol.42 No.6

<P>Summary</P><P>Glycine-rich RNA-binding proteins (GR-RBPs) have been implicated to play roles in post-transcriptional regulation of gene expression in plants under various stress conditions, but the functional roles of GR-RBPs under stress conditions remain to be verified. Here, we examine the biological roles of a GR-RBP, designated atRZ-1a, in <I>Arabidopsis thaliana</I> under stress conditions. <I>atRZ-1a</I> was expressed ubiquitously in various Arabidopsis organs including stems, roots, leaves, flowers, and siliques. The transcript level of <I>atRZ-1a</I> increased markedly by cold stress, whereas its expression was marginally downregulated by drought stress or abscisic acid treatment. Germination and seedling growth of the loss-of-function mutants were retarded remarkably compared with those of the wild type under cold stress. In contrast, the transgenic Arabidopsis plants that overexpress <I>atRZ-1a</I> displayed earlier germination and better seedling growth than the wild type under cold stress. Moreover, the atRZ-1a-overexpressing transgenic Arabidopsis plants were more freezing tolerant than the wild-type plants. Heterologous expression of atRZ-1a in <I>Escherichia coli</I> demonstrated that the <I>E. coli</I> cells expressing atRZ-1a displayed much higher growth rate than the non-transformed cells after cold shock. These results provide evidence that atRZ-1a affects seed germination and seedling growth under low temperature and plays a role in the enhancement of freezing tolerance in Arabidopsis plants.</P>

Arabidopsis zinc finger proteins AtC3H49/AtTZF3 and AtC3H20/AtTZF2 are involved in ABA and JA responses.

Lee, Sun-ji,Jung, Hyun Ju,Kang, Hunseung,Kim, Soo Young Japanese Society of Plant Physiologists 2012 Plant & cell physiology Vol.53 No.4

<P>There are 68 CCCH zinc finger protein genes in the Arabidopsis genome. However, only a few of them have been characerized functionally. In this paper, we report the function of two Arabidopsis CCCH zinc finger proteins AtC3H49/AtTZF3 and AtC3H20/AtTZF2. To investigate their functions, we examined their expression patterns and analyzed their overexpression and knockout(KO)/RNA interference (RNAi) phenotypes. Both AtC3H49/AtTZF3 and AtC3H20/AtTZF2 genes were expressed in various vegetative tissues and in flowers, and their encoded proteins were localized in the cytoplasm. Overexpression of AtC3H49/AtTZF3 or AtC3H20/AtTZF2 conferred ABA hypersensitivity, reduced transpiration and enhanced drought tolerance. Their overexpression also altered the plant growth pattern. The transgenic plants grew slowly during the early stage of growth, but their growth rates were accelerated at later stages, and mature plants were larger than the wild-type plants. Moreover, the transgenic plants displayed delayed senescence and enhanced longevity. Subsequent experiments showed that jasmonic acid (JA)-induced senescence was also delayed. Microarray and quantitative reverse transcription-PCR analyses indicated that the expression of a number of genes involved in JA, ABA and biotic/abiotic stress responses was altered in the transgenic lines. Recombinant AtC3H49/AtTZF3 and AtC3H20/AtTZF2 proteins displayed RNase activity in vitro, suggesting that they may be involved in mRNA turnover process. The knockout/RNAi lines of AtC3H49/AtTZF3 and AtC3H20/AtTZF2 exhibited weak phenotypes, presumably because of their functional redundancy.</P>

Water and H₂O₂ Permeability of Aquaporins Isolated from Cucumber and Figleaf Gourd

Ji Ye Rhee,Maki Katsuhara,Hunseung Kang,Gap Chae Chung 한국원예학회 2010 Horticulture, Environment, and Biotechnology Vol.51 No.3

Cucumber aquaporin gene, CsPIP1;1 and figleaf gourd aquaporin gene CfPIP2;1 were injected to Xenopus oocytes in order to study water transport activity. While CsPIP1;1 did not transport any water and was not responsive to mercury, oocyte injected with CfPIP2;1 rapidly increased their volume without saturation indicating active water transport. Calculation of water permeability of oocytes clearly distinguished the two genes. In response to exogenous application of H₂O₂, only CfPIP2;1 responded, reducing osmotic water permeability. Transgenic Arabidopsis plants overexpressing aquaporin genes did not respond to applied H₂O₂.

Identification of direct targets of transcription factor MYB46 provides insights into the transcriptional regulation of secondary wall biosynthesis

Kim, Won-Chan,Kim, Joo-Yeol,Ko, Jae-Heung,Kang, Hunseung,Han, Kyung-Hwan Springer-Verlag 2014 Plant Molecular Biology Vol.85 No.6

Wheat (Triticum aestivum) zinc finger-containing glycine-rich RNA-binding protein TaRZ1 affects plant growth and defense response in Arabidopsis thaliana

Xu, Tao,Lee, Hwa Jung,Sy, Nguyen Dinh,Kang, Hunseung Springer-Verlag 2015 Plant growth regulation Vol.76 No.3