歡迎點擊「PaperRss」↑關注我們！
F-Actin Meditated Focusing of Vesicles at the Cell Tip Is Essential for Polarized Growth
Plant Physiology Preview Papers|Bibeau, J. P., Kingsley, J. L., Furt, F., Tuzel, E., Vidali, L.
Filamentous actin has been shown to be essential for tip growth in an array of plant models, including Physcomitrella patens. One hypothesis is that diffusion can transport secretory vesicles, while actin plays a regulatory role during secretion. Alternatively, it is possible that actin-based transport is necessary to overcome vesicle transport limitations to sustain secretion. Therefore, a quantitative analysis of diffusion, secretion kinetics and geometry is necessary to clarify the role of actin in polarized growth. Using FRAP analysis, we first show that secretory vesicles move toward and accumulate at the tip in an actin-dependent manner. We then depolymerized F-actin to decouple vesicle diffusion from actin-mediated transport, and measured the diffusion coefficient and concentration of vesicles. Using these values, we constructed a theoretical diffusion-based model for growth, demonstrating that with fast-enough vesicle fusion kinetics, diffusion could support normal cell growth rates. We further refined our model to explore how experimentally-extrapolated vesicle fusion kinetics and the size of the secretion zone limit diffusion-based growth. This model predicts that diffusion-mediated growth is dependent on the size of the region of exocytosis at the tip, and that diffusion-based growth would be significantly slower than normal cell growth. To further explore the size of the secretion zone, we used a cell wall-degradation enzyme cocktail, and determined that the secretion zone is smaller than in diameter at the tip. Taken together our results highlight the requirement for active transport in polarized growth and provide important insight into vesicle secretion during tip growth.
歡迎點擊「PaperRss」↑關注我們！
Cell Host Microbe. 2016 Dec 14;20(6):758-769. doi: 10.1016/j.chom.2016.10.023.
An E3 Ubiquitin Ligase-BAG Protein Module Controls Plant Innate Immunity and Broad-Spectrum Disease Resistance.AbstractProgrammed cell death (PCD) and immunity in plants are tightly controlled to promote antimicrobial defense while preventing autoimmunity. However, the mechanisms contributing to this immune homeostasis are poorly understood. Here, we isolated a rice mutant ebr1 (enhanced blight and blast resistance 1) that shows enhanced broad-spectrum bacterial and fungal disease resistance, but displays spontaneous PCD, autoimmunity, and stunted growth. EBR1 encodes an E3 ubiquitin ligase that interacts with OsBAG4, which belongs to the BAG (Bcl-2-associated athanogene) family that functions in cell death, growth arrest, and immune responses in mammals. EBR1 directly targets OsBAG4 for ubiquitination-mediated degradation. Elevated levels of OsBAG4 in rice are necessary and sufficient to trigger PCD and enhanced disease resistance to pathogenic infection, most likely by activating pathogen-associated molecular patterns-triggered immunity (PTI). Together, our study suggests that an E3-BAG module orchestrates innate immune homeostasis and coordinates the trade-off between defense and growth in plants.
歡迎點擊「PaperRss」↑關注我們！
3Development：BR信號途徑參與擬南芥根分生組織的細胞分裂和原生韌皮部分化
Development. 2017 Jan 15;144(2):272-280. doi: 10.1242/dev.145623.
Brassinosteroid signaling directs formative cell divisions and protophloem differentiation in Arabidopsis root meristems.
Kang YH1, Breda A1, Hardtke CS2.
Author information
1Department of Plant Molecular Biology, University of Lausanne, Biophore Building, Lausanne CH-1015, Switzerland.2Department of Plant Molecular Biology, University of Lausanne, Biophore Building, Lausanne CH-1015, Switzerland christian.hardtke@unil.ch.
Abstract
Brassinosteroids (BRs) trigger an intracellular signaling cascade through its receptors BR INSENSITIVE 1 (BRI1), BRI1-LIKE 1 (BRL1) and BRL3. Recent studies suggest that BR-independent inputs related to vascular differentiation, for instance root protophloem development, modulate downstream BR signaling components. Here, we report that protophloem sieve element differentiation is indeed impaired in bri1 brl1 brl3 mutants, although this effect might not be mediated by canonical downstream BR signaling components. We also found that their small meristem size is entirely explained by reduced cell elongation, which is, however, accompanied by supernumerary formative cell divisions in the radial dimension. Thus, reduced cell expansion in conjunction with growth retardation, because of the need to accommodate supernumerary formative divisions, can account for the overall short root phenotype of BR signaling mutants. Tissue-specific re-addition of BRI1 activity partially rescued subsets of these defects through partly cell-autonomous, partly non-cell-autonomous effects. However, protophloem-specific BRI1 expression essentially rescued all major bri1 brl1 brl3 root meristem phenotypes. Our data suggest that BR perception in the protophloem is sufficient to systemically convey BR action in the root meristem context.
An Efficient Method for the Isolation of Highly Purified RNA from Seeds for Use in Quantitative Transcriptome Analysis.
J Vis Exp. 2017 Jan 11;(119):
Authors: Kanai M, Mano S, Nishimura M
Abstract
Plant seeds accumulate large amounts of storage reserves comprising biodegradable organic matter. Humans rely on seed storage reserves for food and as industrial materials. Gene expression profiles are powerful tools for investigating metabolic regulation in plant cells. Therefore, detailed, accurate gene expression profiles during seed development are required for crop breeding. Acquiring highly purified RNA is essential for producing these profiles. Efficient methods are needed to isolate highly purified RNA from seeds. Here, we describe a method for isolating RNA from seeds containing large amounts of oils, proteins, and polyphenols, which have inhibitory effects on high-purity RNA isolation. Our method enables highly purified RNA to be obtained from seeds without the use of phenol, chloroform, or additional processes for RNA purification. This method is applicable to Arabidopsis, rapeseed, and soybean seeds. Our method will be useful for monitoring the expression patterns of low level transcripts in developing and mature seeds.
歡迎點擊「PaperRss」↑關注我們！
往期文章推薦：（直接點擊瀏覽）
Plant Physiology：lncRNA增強植物抗旱、鹽分等非生物脅迫
簡訊：全球首例可攜式DNA測序儀完成田間病害測序
Cell Host & Microbe：新基因編輯工具CRISPR-Cas10效率更高！
2017中科院院士候選人：植物生命科學領域何祖華、劉耀光、謝道昕、種康等光榮上榜
震撼：黨的十八大以來中國科學院重大科技成果展
方舟子：「雙一流學科主任」涉嫌論文造假被撤稿
Nature plants：醋能幫助作物抗旱
學術老虎？一長江學者被50萬元「絆倒」
部分文章和信息來源於網際網路，不代表本訂閱號贊同其觀點並對其真實性負責。如轉載內容涉及版權等問題，小編將迅速採取刪除措施。本訂閱號原創內容，轉載時，請註明來源「PaperRSS」。
為方便小木蟲裡研究生們的科研生活交流。PaperRss微信公眾平臺特建立了兩個全國博士就業交流群。建群半年已來，兩群成員已經達到700多人。成員包含了美國、歐洲、日本、清華北大、中科院名校、地方大學博士以及企業經理，HR等；涉及各學科領域方向。歡迎各位新人直接搜索 IGDB2010 剛哥微信號申請加入，入群請務必註明「姓名-單位-研究方向」。