Special Issue: For the 75th Anniversary of the Botanical Society of China   

July 2008, Volume 50 Issue 7, Pages 769-928.


Cover Caption:
For the 75th Anniversary of the Botanical Society of China
This year, 2008, witnesses the 75th anniversary of the Botanical Society of China (BSC). The BSC is one of the largest Chinese academic societies, with more than 14 000 members across the whole country. JIPB, the journal sponsored by the BSC and the Institute of Botany, CAS, has been supporting the society and is also supported by members of the society for the last 56 years. This special issue, organized by the JIPB Executive Editor, Dr. Chun-Ming Liu, is dedicated to those pioneers who have laid the foundation of plant science research in China. The portraits of some of these early scientists are shown on the cover: Ren-Chang Ching, Hsen-Hsu Hu and Woon-Young Chun (upper panel, from left to right), Sung-Shu Chien and Pei-Sung Tang (lower panel, from left to right). The photographs were collected by Dr. Jin-Zhong Cui.

 

          Editorial
2008, a Year for Plants to Celebrate  
Author: Dong Liu and Chun-Ming Liu
Journal of Integrative Plant Biology 2008 50(7): 769-770
DOI: 10.1111/j.1744-7909.2008.00726.x
      
    2008 is a special year for the Botanical Society of China (BSC) for two reasons. The first one is for the 75th anniversary of the Society, and the second one is for Prof. Zhengyi Wu who received The State Supreme Science and Technology Award, the country's highest science honor. This special issue, with a collection of 16 articles, is dedicated to these events. On January 8, 2008, the Chinese President Jintao Hu handed the award to Prof. Zhengyi Wu, for his life-long achievement in plant taxonomy. Prof. Wu, the Honorary President of BSC, and many other Chinese botanists have been working together for more than 50 years to study plant species in China. In collaboration with botanists in UK and USA, a book series called "Flora of China" is being published in English (for more information, see Dezhu Li, pp. 771每777). BSC was established in 1933 by a group of 19 board members, who received their scientific training overseas and returned to China to start botanical research and education. The founding members of BSC include Dr. Chongshu Qian (Sung-Shu Chien, 1883每1965), Dr. Xiansu Hu (Hsen-Hsu Hu, 1894每1968), Dr. Huanyong Chen (Woon-Young Chun), Dr. Jingyu Zhang, Dr. Jitong Li et al., with Dr. Qian being the first President. Though the society had only 105 members at its inception, it played a critical role in establishing botany, a "new science" at that time, in China. During its history, BSC's activities have been stopped twice, the first time for 13 years between 1937 and 1949 during the war period, and the second time for 12 years between 1966 and 1978 during the "Cultural Revolution" period. However, even during the war period, many of BSC members continued to conduct their scientific work despite the lack of chemicals and instruments, the food shortage, and frequent air bombings. In fact, some great discoveries were made at that time by these members, with 8 papers published in Science and Nature, and several in other prestigious international journals (Tang 1983; Chen et al. 2006). Going through all kinds of hardships, BSC has revitalized itself today to become one of the largest professional associations in China, with 14 800 members. In the last 10 years, research in plant sciences in China has entered a golden time, with much increased financial support and many well-trained scientists returning from Western countries. The article written by Chen et al. in 2006 provides a comprehensive survey of the facts in this field. More importantly, the National Botanical Conference to be held in Lanzhou this year (July 12每16, 2008) will showcase the contemporary situation of the society. One of the major tasks of BSC is to develop its own scientific journal. In 1952, a quarterly magazine, Acta Botanica Sinica, was established by BSC as its official publication. At that time, all articles were published in Chinese, but with an extensive abstract in English. The first research article published on the first issue was from Dr. Tsung-Hsun Tsao, reporting the effects of reproduction on the metabolism of higher plants (Tsao 1952). Since then, this journal has become the national platform where Chinese plant scientists report their experimental results and share the newest advancement. Following the trend of using English as the international medium for scientific communication, between 1995 and 2001, the journal published its articles in both Chinese and English. After a 6-year transition period, in 2002, the Editorial Board decided to convert Acta Botanica Sinica to an English-only journal. In collaboration with Blackwell Publishing (now Wiley-Blackwell), the journal has started its new Long March with a new name〞Journal of Integrative Plant Biology (JIPB), and of course, a new outlook as well. In 2007, in order to facilitate access for its readers, JIPB made tremendous efforts to set up an online hub (http://www.jipb.net) to carry out all editorial activities online, and to allow readers to access all articles online (including all articles published from 56 years ago to the latest articles from the point of acceptance). To further increase the impact of JIPB in the international plant science communities, in 2008, an international Editorial Board has been established, through recruiting renowned scientists as Associate and Handling Editors, to monitor the reviewing process. This ensures all published work with a high standard. In this issue, 12 invited review articles and 4 research articles are included. The "Milestone" article written by Dr. Dezhu Li, the Director of Kunming Institute of Botany, outlines the classification system developed by Prof. Zhengyi Wu and his colleagues. The other 11 articles provide comprehensive over-views on membrane-associated ion transporter (Yi-Fang Chen et al., pp. 835每848), phosphate starvation (Hui Yuan and Dong Liu, pp. 849每859), ethylene (Ziqiang Zhu and Hongwei Guo, pp. 808每815) and GA (Xiu-Hua Gao et al., pp. 825每834) signal transduction, gamete recognition (Xiong-Bo Peng and Meng-Xiang Sun, pp. 868每874), fertilization and the initiation of zygotic embryogenesis (Yong-Feng Fan et al., pp. 860每867), cell fate determination during organogenesis in vitro (Xiang Yu Zhao et al., pp. 816每824), carotenoid metabolism (Shan Lu and Li Li, pp. 778每785), nitrogen fixation (Qi Cheng, pp. 786每798), disease resistance and symbiosis (Songzi Zhao and Xiaoquan Qi, pp. 799每807), and epigenetic regulation through histone deacetylases (Courtney Hollender and Zhongchi Liu, pp. 875每885). No doubt the articles included in this special issue do not intent to present an over-view of plant science in China, which is mission impossible. Instead, we wanted to use these high quality articles to commemorate those pioneers who had worked so hard during a period of great struggle in China to carry out plant biological research, and to remember those who had sacrificed their lives during the period. Definitely, we owe them a lot. We thank all the authors who have contributed their articles in this special issue, and our Editorial Staff who have been with us to produce this issue within such short notice.
Abstract (Browse 2085)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Molecular Ecology and Evolution
Floristics and Plant Biogeography in China  
Author: De-Zhu Li
Journal of Integrative Plant Biology 2008 50(7): 771-777
DOI: 10.1111/j.1744-7909.2008.00711.x
      
    In 1998, a revolutionary system of angiosperm classification, the Angiosperm Phylogeny Group system was published. Meanwhile, another new system of classification of angiosperms, the eight-class system was proposed by C. Y. Wu and colleagues based on long term work on the flora of China. The Flora Reipublicae Popularis Sinicae project was initiated in 1959 and completed by 2004. It is the largest Flora so far completed in the world, including 31 228 species of vascular plants, or one-eighth of the global plant diversity. The English-language and updated Flora of China (FOC) is an international joint effort initiated in 1988 and accelerated in 1998. Up to now, 15 of the 24 volumes of the FOC have been published. Based on the floristic data, the composition, characteristics, floristic divisions and affinities of the flora of China have been studied by Wu and colleagues since 1965. In the past 10 years, analyses of the available floristic data have been very productive. The East Asiatic Floristic Kingdom was proposed in 1998. All 346 families of angiosperms in China, according to the eight-class system of classification, were comprehensively discussed by using knowledge of current and historical distribution of seed plants in the world, together with some morphological and molecular data. A scheme of distribution patterns or areal-types of families and genera of seed plants in China was modified and elucidated, together with a proposed scheme of areal-types of the world. Molecular phylogenetic and biogeographical studies of angiosperms in China in the past 10 years also witnessed a progressive development. Integration of morphological and molecular data and fossil evidence revealed some significant results. Eastern Asia, which used to be regarded as an important center of survival during the ice age, is likely an important center of diversification of angiosperms.
Abstract (Browse 1574)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Metabolism and Biochemistry
Carotenoid Metabolism: Biosynthesis, Regulation, and Beyond  
Author: Shan Lu and Li Li
Journal of Integrative Plant Biology 2008 50(7): 778-785
DOI: 10.1111/j.1744-7909.2008.00708.x
      
    Carotenoids are indispensable to plants and play a critical role in human nutrition and health. Significant progress has been made in our understanding of carotenoid metabolism in plants. The biosynthetic pathway has been extensively studied. Nearly all the genes encoding the biosynthetic enzymes have been isolated and characterized from various organisms. In recent years, there is an increasing body of work on the signaling pathways and plastid development, which might provide global control of carotenoid biosynthesis and accumulation. Herein, we will highlight recent progress on the biosynthesis, regulation, and metabolic engineering of carotenoids in plants, as well as the future research towards elucidating the regulatory mechanisms and metabolic network that control carotenoid metabolism.
Abstract (Browse 2188)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Perspectives in Biological Nitrogen Fixation Research  
Author: Qi Cheng
Journal of Integrative Plant Biology 2008 50(7): 786-798
DOI: 10.1111/j.1744-7909.2008.00700.x
      
    Nitrogen fixation, along with photosynthesis is the basis of all life on earth. Current understanding suggests that no plant fixes its own nitrogen. Some plants (mainly legumes) fix nitrogen via symbiotic anaerobic microorganisms (mainly rhizobia). The nature of biological nitrogen fixation is that the dinitrogenase catalyzes the reaction-splitting triple-bond inert atmospheric nitrogen (N2) into organic ammonia molecule (NH3). All known nitrogenases are found to be prokaryotic, multi-complex and normally oxygen liable. Not surprisingly, the engineering of autonomous nitrogen-fixing plants would be a long-term effort because it requires the assembly of a complex enzyme and provision of anaerobic conditions. However, in the light of evolving protein catalysts, the anaerobic enzyme has almost certainly been replaced in many reactions by the more efficient and irreversible aerobic version that uses O2. On the other hand, nature has shown numerous examples of evolutionary convergence where an enzyme catalyzing a highly specific, O2-requiring reaction has an oxygen-independent counterpart, able to carry out the same reaction under anoxic conditions. In this review, I attempt to take the reader on a simplified journey from conventional nitrogenase complex to a possible simplified version of a yet to be discovered light-utilizing nitrogenase.
Abstract (Browse 1910)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Signaling in Plant Disease Resistance and Symbiosis  
Author: Songzi Zhao and Xiaoquan Qi
Journal of Integrative Plant Biology 2008 50(7): 799-807
DOI: 10.1111/j.1744-7909.2008.00702.x
      
    Interactions between plants and microbes result in plant disease and symbiosis. The former causes considerable economic damage in modern agriculture, while the latter has produced great beneficial effects to our agriculture system. Comparison of the two interactions has revealed that a common panel of signaling pathways might participate in the establishment of the equilibrium between plant and microbes or its break-up. Plants appear to detect both pathogenic and symbiotic microbes by a similar set of genes. All symbiotic microbes seem to produce effectors to overcome plant basal defenses and it is speculated that symbiotic effectors have functions similar to pathogenic ones. Signaling molecules, salicylic acid (SA), jasmonic acid (JA) and ethylene (ET), are involved in both plant defense and symbiosis. Switching off signals contributing to deterioration of disease symptom would establish a new equilibrium between plant and pathogenic microbes. This would facilitate the development of strategies for durable disease resistance.
Abstract (Browse 2502)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Plant-environmental Interactions
Genetic Basis of Ethylene Perception and Signal Transduction in Arabidopsis  
Author: Ziqiang Zhu and Hongwei Guo
Journal of Integrative Plant Biology 2008 50(7): 808-815
DOI: 10.1111/j.1744-7909.2008.00710.x
      
    Ethylene is a simple gaseous hormone in plants. It plays important roles in plant development and stress tolerance. In the presence of ethylene treatment, all ethylene receptors are in an activated form, which can physically interact with CTR1 and consequently recruit CTR1 protein to endoplasmic reticulum membrane to activate it. Activated CTR1 suppresses the downstream signal transduction by an unknown mechanism. Upon binding to its receptors, ethylene will inactivate the receptor/CTR1 module and in turn alleviate their inhibitory effect on two positive regulators acting downstream of CTR1: EIN2 and EIN3. Genetic study reveals that EIN2 is an essential component in the ethylene signaling pathway but its biochemical function remains a mystery. EIN3 is a plant-specific transcription factor and its protein abundance in the nucleus is rapidly induced upon ethylene treatment. In the absence of ethylene signal, EIN3 protein is degraded by an SCF complex containing one of the two F-box proteins EBF1/EBF2 in a 26S proteasome-dependent manner. EIN3 can bind to the promoter sequences of a number of downstream components, such as ERFs, which in turn bind to a GCC box, a cis-element found in many ethylene-regulated defense genes. Ethylene has been shown to also regulate many other hormones' signaling pathways including auxin, abscisic acid and jasmonic acid, implying the existence of complicated signaling networks in the growth, development and defense responses of various plants.
Abstract (Browse 2200)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Cell Fate Switch during In Vitro Plant Organogenesis  
Author: Xiang Yu Zhao, Ying Hua Su, Zhi Juan Cheng and Xian Sheng Zhang
Journal of Integrative Plant Biology 2008 50(7): 816-824
DOI: 10.1111/j.1744-7909.2008.00701.x
      
    Plant mature cells have the capability to reverse their state of differentiation and produce new organs under cultured conditions. Two phases, dedifferentiation and redifferentiation, are commonly characterized during in vitro organogenesis. In these processes, cells undergo fate switch several times regulated by both extrinsic and intrinsic factors, which are associated with reentry to the cell cycle, the balance between euchromatin and heterochromatin, reprogramming of gene expression, and so forth. This short article reviews the advances in the mechanism of organ regeneration from plant somatic cells in molecular, genomic and epigenetic aspects, aiming to provide important information on the mechanism underlying cell fate switch during in vitro plant organogenesis.
Abstract (Browse 1906)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Evolutionarily Conserved DELLA-mediated Gibberellin Signaling in Plants  
Author: Xiu-Hua Gao, Xian-Zhong Huang, Sen-Lin Xiao and Xiang-Dong Fu
Journal of Integrative Plant Biology 2008 50(7): 825-834
DOI: 10.1111/j.1744-7909.2008.00703.x
      
    Gibberellins (GAs) play important roles in many essential plant growth and development processes. A family of nuclear growth-repressing DELLA proteins is the key component in GA signaling. GA perception is mediated by GID1, and the key event of GA signaling is the degradation of DELLA proteins via the 26S proteasome pathway. DELLA proteins integrating other plant hormones signaling and environmental cue modulating plant growth and development have been revealed. GA turning on the de-DELLA-repressing system is conserved, and independently establishes step-by-step recruitment of GA-stimulated GID1-DELLA interaction and DELLA growth-repression functions during land plant evolution. These discoveries open new prospects for the understanding of GA action and DELLA-mediated signaling in plants.
Abstract (Browse 2119)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Membrane Transporters for Nitrogen, Phosphate and Potassium Uptake in Plants  
Author: Yi-Fang Chen, Yi Wang and Wei-Hua Wu
Journal of Integrative Plant Biology 2008 50(7): 835-848
DOI: 10.1111/j.1744-7909.2008.00707.x
      
    Nitrogen, phosphorous and potassium are essential nutrients for plant growth and development. However, their contents in soils are limited so that crop production needs to invest a lot for fertilizer supply. To explore the genetic potentialities of crops (or plants) for their nutrient utilization efficiency has been an important research task for many years. In fact, a number of evidences have revealed that plants, during their evolution, have developed many morphological, physiological, biochemical and molecular adaptation mechanisms for acquiring nitrate, phosphate and potassium under stress conditions. Recent discoveries of many transporters and channels for nitrate, phosphate and potassium uptake have opened up opportunities to study the molecular regulatory mechanisms for acquisition of these nutrients. This review aims to briefly discuss the genes and gene families for these transporters and channels. In addition, the functions and regulation of some important transporters and channels are particularly emphasized.
Abstract (Browse 2382)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Signaling Components Involved in Plant Responses to Phosphate Starvation  
Author: Hui Yuan and Dong Liu
Journal of Integrative Plant Biology 2008 50(7): 849-859
DOI: 10.1111/j.1744-7909.2008.00709.x
      
    Phosphorus is one of the macronutrients essential for plant growth and development. Many soils around the world are deficient in phosphate (Pi) which is the form of phosphorus that plants can absorb and utilize. To cope with the stress of Pi starvation, plants have evolved many elaborate strategies to enhance the acquisition and utilization of Pi from the environment. These strategies include morphological, biochemical and physiological responses which ultimately enable plants to better survive under low Pi conditions. Though these adaptive responses have been well described because of their ecological and agricultural importance, our studies on the molecular mechanisms underlying these responses are still in their infancy. In the last decade, significant progresses have been made towards the identification of the molecular components which are involved in the control of plant responses to Pi starvation. In this article, we first provide an overview of some major responses of plants to Pi starvation, then summarize what we have known so far about the signaling components involved in these responses, as well as the roles of sugar and phytohormones.
Abstract (Browse 1937)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Cell and Developmental Biology
Sexual Reproduction in Higher Plants I: Fertilization and the Initiation of Zygotic Program  
Author: Yong-Feng Fan, Li Jiang, Hua-Qin Gong and Chun-Ming Liu
Journal of Integrative Plant Biology 2008 50(7): 860-867
DOI: 10.1111/j.1744-7909.2008.00705.x
      
    Sexual plant reproduction is a critical developmental step in the life cycle of higher plants, to allow maternal and paternal genes to be transmitted in a highly regulated manner to the next generation. During evolution, a whole set of signal transduction machinery is developed by plants to ensure an error-free recognition between male and female gametes and initiation of zygotic program. In the past few years, the molecular machineries underlying this biological process have been elucidated, particularly on the importance of synergid cells in pollen tube guidance, the Ca++ spike as the immediate response of fertilization and the epigenetic regulation of parental gene expressions in early zygotic embryogenesis. This review outlines the most recent development in this area.
Abstract (Browse 2355)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Gamete Recognition in Higher Plants: An Abstruse but Charming Mystery  
Author: Xiong-Bo Peng and Meng-Xiang Sun
Journal of Integrative Plant Biology 2008 50(7): 868-874
DOI: 10.1111/j.1744-7909.2008.00706.x
      
    Although much effort has been made to uncover the mechanism underlying double fertilization, little knowledge has been acquired for understanding the molecular base of gamete recognition, mainly because of technical limitations. Still, progress has been made in terms of the mechanism, including the identification of candidate molecules that are involved in gamete recognition in angiosperms. New cues for gamete recognition have been found by the successful separation of the gametes and construction of gamete-specific cDNA libraries in several species, and the application of molecular approaches for studying this process by mutations. Thus, the topic is considered an abstruse but charming mystery.
Abstract (Browse 2106)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Histone Deacetylase Genes in Arabidopsis Development  
Author: Courtney Hollender and Zhongchi Liu
Journal of Integrative Plant Biology 2008 50(7): 875-885
DOI: 10.1111/j.1744-7909.2008.00704.x
      
    Histone acetylation and deacetylation are directly connected with transcriptional activation and silencing in eukaryotes. Gene families for enzymes that accomplish these histone modifications show surprising complexity in domain organization, tissue-specific expression, and function. This review is focused on the family of histone deacetylases (HDACs) that remove the acetyl group from core histone tails, resulting in a "closed" chromatin and transcriptional repression. In Arabidopsis, 18 HDAC genes are divided into three different types 每 RPD3-like, HD-tuin and sirtuin 每 with two or more members in each type. The structural feature of each HDAC class, the expression profile of each HDAC gene during development and functional insights of important family members are summarized here. It is clear that HDACs are an important class of global transcriptional regulators that play crucial roles in plant development, defense, and adaptation.
Abstract (Browse 2292)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Comparative Analysis of JmjC Domain-containing Proteins Reveals the Potential Histone Demethylases in Arabidopsis and Rice  
Author: Falong Lu, Guanglin Li, Xia Cui, Chunyan Liu, Xiu-Jie Wang, Xiaofeng Cao
Journal of Integrative Plant Biology 2008 50(7): 886-896
DOI: 10.1111/j.1744-7909.2008.00692.x
      
    Histone methylation homeostasis is achieved by controlling the balance between methylation and demethylation to maintain chromatin function and developmental regulation. In animals, a conserved Jumonji C (JmjC) domain was found in a large group of histone demethylases. However, it is still unclear whether plants also contain the JmjC domain-containing active histone demethylases. Here we performed genome-wide screen and phylogenetic analysis of JmjC domain-containing proteins in the dicot plant, Arabidopsis, and monocot plant rice, and found 21 and 20 JmjC domain-containing, respectively. We also examined the expression of JmjC domain-containing proteins and compared them to human JmjC counterparts for potential enzymatic activity. The spatial expression patterns of the Arabidopsis JmjC domain-containing genes revealed that they are all actively transcribed genes. These active plant JmjC domain-containing genes could possibly function in epigenetic regulation to antagonize the activity of the large number of putative SET domain-containing histone methyltransferase activity to dynamically regulate histone methylation homeostasis.
Abstract (Browse 2347)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Subcellular Localizations of AS1 and AS2 Suggest Their Common and Distinct Roles in Plant Development  
Author: Yan Zhu, Ziyu Li, Ben Xu, Hongda Li, Lingjian Wang, Aiwu Dong, Hai Huang
Journal of Integrative Plant Biology 2008 50(7): 897-905
DOI: 10.1111/j.1744-7909.2008.00693.x
      
    During leaf organogenesis, a critical step for normal leaf primordium initiation is the repression of the class 1 KNOTTED1-like homeobox (KNOX) genes. After leaf primordia are formed, they must establish polarity for normal leaf morphogenesis. Recent studies have led to the identification of a number of genes that participate in the class 1 KNOX gene repression and/or the leaf polarity establishment. ASTMMETRIC LEAVES1 and 2 (AS1 and AS2) are two of these genes, which are critical for both of these two processes. As a first step towards understanding the molecular genetic basis of the AS1每AS2 action, we determined the subcellular localizations of the two proteins in both tobacco BY2 cells and Arabidopsis plants, by fusing them to yellow/cyan fluorescent protein (YFP/CFP). Our data showed that AS1 and AS2 alone were predominantly localized in the nucleolus and the nucleoplasm, respectively. The presence of both AS1 and AS2 proteins in the same interphase cell demonstrated their co-localization in both nucleolus and nucleoplasm. In addition, AS1 alone was able to associate with the condensed chromosome in the metaphase cell. Our data suggest that AS1, AS2 and the AS1-AS2 protein complex may have distinct functions, which are all required for normal plant development.
Abstract (Browse 2071)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
SAD2 in Arabidopsis Functions in Trichome Initiation through Mediating GL3 Function and Regulating GL1, TTG1 and GL2 Expression  
Author: Ying Gao, Ximing Gong, Wanhong Cao, Jinfeng Zhao, Liqin Fu, Xuechen Wang, Karen S. Schumaker and Yan Guo
Journal of Integrative Plant Biology 2008 50(7): 906-917
DOI: 10.1111/j.1744-7909.2008.00695.x
      
    Most genes identified that control Arabidopsis trichome initiation and formation are transcription factors or regulatory components in transcriptional networks and include GLABROUS1 (GL1), GLABRA2 (GL2), GLABRA3 (GL3) and TRANSPARENT TESTA GLABRA1 (TTG1). Herein, we report that an importin 汕-like protein, SENSITIVE TO ABA AND DROUGHT2 (SAD2), is required for trichome initiation. Mutations in SAD2 disrupted trichome initiation resulting in reduced trichome number, but had no effect on trichome development or root hair number and development. Expression levels of GL1, MYB23, GL2 and TTG1 were reduced in shoots of sad2 mutants while expression levels of GL3 and ENHANCER OF GLABRA3 (EGL3) were enhanced. Overexpression of GL3 increased trichome numbers in wild type but not in sad2 mutants, indicating that the function of the GL3 protein is altered in the sad2 mutants. In contrast, overexpression of GFP-GL1 decreased trichome number in both wild type and sad2. Double mutant analysis of gl1 sad2 and gl3 sad2 indicated that SAD2 functions genetically, at least in part, in the same pathway with these two genes. Co-immunoprecipitation indicated that the sad2 mutation does not disrupt formation of the TTG1-GL3-GL1 complex. Analysis of GFP fusions of GL1, GL2, GL3 and TTG1 suggested that these proteins are most likely not direct cargo of SAD2. Our data suggest that SAD2 is involved in trichome initiation by regulating these nuclear genes.
Abstract (Browse 2509)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Novel Nuclear Protein ALC-INTERACTING PROTEIN1 is Expressed in Vascular and Mesocarp Cells in Arabidopsis  
Author: Fang Wang, Dong-Qiao Shi, Jie Liu and Wei-Cai Yang
Journal of Integrative Plant Biology 2008 50(7): 918-927
DOI: 10.1111/j.1744-7909.2008.00694.x
      
    Pod shattering is an agronomical trait that is a result of the coordinated action of cell differentiation and separation. In Arabidopsis, pod shattering is controlled by a complex genetic network in which ALCATRAZ (ALC), a member of the basic helix-loop-helix family, is critical for cell separation during fruit dehiscence. Herein, we report the identification of ALC-INTERACTING PROTEIN1 (ACI1) via the yeast two-hybrid screen. ACI1 encodes a nuclear protein with a lysine-rich domain and a C-terminal serine-rich domain. ACI1 is mainly expressed in the vascular system throughout the plant and mesocarp of the valve in siliques. Our data showed that ACI1 interacts strongly with the N-terminal portion of ALC in yeast cells and in plant cells in the nucleus as demonstrated by bimolecular fluorescence complementation assay. Both ACI1 and ALC share an overlapping expression pattern, suggesting that they likely function together in planta. However, no detectable phenotype was found in plants with reduced ACI1 expression by RNA interference technology, suggesting that ACI1 may be redundant. Taken together, these data indicate that ALC may interact with ACI1 and its homologs to control cell separation during fruit dehiscence in Arabidopsis.
Abstract (Browse 1975)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
 

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