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mgflyx_001至尊木虫 (著名写手)
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【转帖】国外科学家发现决定植物种子大小的关键基因已有5人参与
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来自英国诺维奇约翰英纳斯中心和德国弗莱堡大学的科学家发现了决定植物种子的大小的基因，这可能导致改良作物新方法的诞生。 在现代农业中提高作物种子或籽粒大小在作物改良中很关键。随着世界人口的增长，进一步提高作物产量是农业研究的主要目标。 在生物技术和生物科学研究理事会（BBSRC）的资金支持下，Michael Lenhard发现了在模型植物拟南芥中决定整体种子大小的基因，目前正在研究可用于作物的改良的办法。 美国国家科学院院刊发表了约翰英纳斯中心研究小组的新发现，表明该基因以生长中的种子为基础起作用，它产生一个尚未确定的动态生长信号决定最终的种子大小。如果该基因处于关闭状态，就生产小种子；如果这种基因被打开，就产生体积和重量都大三分之一的种子。 这是第一次观察到的这样的种子大小的相互影响，这个基因在植物发展中非常重要。在这项研究应用于作物之前还需要做很多的工作。在实验植物中使种子增大的效果之一是减少了生产的种子总数，所以没有整体产量的增加。与此同时，科学家们却注意到较大种子相对含油量的增加，因此目前正在调查在这种油料种子中改变基因产生的影响。 解开这个基因在确定种子大小方面所起作用之迷，对增加作物产量，确保粮食安全有重要意义。 【来源】天津农业科技信息网 |
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xiaowuhehe
铁杆木虫 (著名写手)
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2楼2010-04-07 16:49:48
3楼2010-04-07 18:43:36
zwdbordeaux
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小木虫(金币+0.5):给个红包，谢谢回帖交流
mgflyx_001(金币+2):谢谢参与交流！ 2010-04-09 20:47
小木虫(金币+0.5):给个红包，谢谢回帖交流
mgflyx_001(金币+2):谢谢参与交流！ 2010-04-09 20:47
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PNAS：调控种子大小的新基因被发现 [日期：2010-01-13] 来源：生物谷 作者： [字体：大 中 小] 转自:http://life.lifesci.cn/html/molecular/2010-01/10775.htm 德国Freiberg大学与英国John Innes中心的科学家发现了模式植物拟南芥中负责控制种子大小的一个新基因，并认为通过操控该基因可以改良作物。 Michael Lenhard及同事发现细胞色素KLU基因调控种子大小。胚珠发育时该基因在珠被中表达，产生一种未知的生长信号，最终决定种子大小。如果该基因被关闭，将产生更小的种子，相反将之过表达，能够产生更高油含量、更大的种子。研究人员认为这是首次发现种子大小上存在交互影响，并且该基因在植物发育中存在重要作用，他们现在正在油菜中研究该基因。 来自英国John Innes中心，德国弗莱堡大学（Universität Freiburg）的研究人员发现了控制种子大小的一个新基因，并提出通过操控该基因可以改良作物。这一研究成果公布在美国国家科学院院刊（PNAS）上。 种子大小是有花植物生活史对策中最重要的功能性状之一。许多研究者对种子大小的进化生态学予以了关注，分别从不同角度探索了种子大小的变异与外因和内因的关系，包括气候与土壤，地理纬度，生境质量，植株个体大小，种子数量及叶片大小等。而迄今为止，关于种子大小变异的机制并未完全清楚，其进化理论仍未建立。 在这篇文章中，研究人员发现细胞色素KLU基因调控种子大小。胚珠发育时该基因在珠被中表达，产生一种未知的生长信号，最终决定种子大小。如果该基因被关闭，将产生更小的种子，相反将之过表达，能够产生更高油含量、更大的种子。研究人员认为这是首次发现种子大小上存在交互影响，并且该基因在植物发育中存在重要作用，他们现在正在油菜中研究该基因。 之前这一研究小组曾在Developmental Cell发文，发现了一种新的控制植物器官大小的胞间信号途径，其作用机制可能类似动物中发现的可移动生长因子。 这种基因即KLU基因，研究人员对大量化学诱变得到的拟南芥突变株进行研究，发现KLU基因的功能缺失会导致器官变小，而其过量表达导致器官过大。对该基因进行克隆测序和结构推断，表明它是细胞色素P450氧化酶系，它通过控制细胞分裂的时间而控制生长。 mRNA原位杂交和空间特异的基因表达等实验表明KLU的表达位点和作用位点不同，能够在一定距离内发挥作用，说明其作用涉及胞间信号传递。而融合蛋白实验表明KLU本身并不具移动性，它的作用可能通过位于其下游的某种可移动生长因子来实现。通过对KLU基因的转录谱分析和双突变分析发现，KLU基因的作用与已知植物激素和其它调控植物生长的已知基因的作用不同，因此它可能通过某种新的未知可移动生长因子起作用。 同一时期，中国科学家也在这一方面获得了一些成果，中科院成都生物研究所孙书存课题组与康奈尔大学K. J. Niklas合作，采用带成熟果实小枝的方法，对亚热带常绿阔叶林森林群落木本植物的种子大小变异进行了研究。结果表明，小枝大小与其果实和种子的产量有正相关关系；小枝大小与种子大小没有直接关联，这可能是因为物种间每颗种子数存在巨大差异所致；小枝水平上，存在种子大小与数量的权衡关系。该项工作从小枝大小的角度上对森林群落木本植物种子大小的进化进行了探讨，同时也为亚热带森林群落木本植物生活史对策研究提供了相关基本资料。该结果发表于2009年第4期新植物学家（New Phytologist）。 生物谷推荐原文出处： PNAS doi: 10.1073/pnas.0907024106 Local maternal control of seed size by KLUH/CYP78A5-dependent growth signaling Nikolai M. Adamski a, Elena Anastasiou b, Sven Eriksson a, Carmel M. O'Neill c and Michael Lenhard a,1 Seed development in plants involves the coordinated growth of the embryo, endosperm, and maternal tissue. Several genes have been identified that influence seed size by acting maternally, such as AUXIN RESPONSE FACTOR2, APETALA2, and DA1. However, given the lack of gain-of-function effects of these genes on seed size, it is unclear whether their activity levels are limiting in WT plants and whether they could thus be used to regulate seed size in development or evolution. Also, whether the altered seed sizes reflect local gene activity or global physiological changes is unknown. Here, we demonstrate that the cytochrome P450 KLUH (KLU) regulates seed size. KLU acts locally in developing flowers to promote seed growth, and its activity level is limiting for seed growth in WT. KLU is expressed in the inner integument of developing ovules, where it non-cell autonomously stimulates cell proliferation, thus determining the growth potential of the seed coat and seed. A KLU-induced increase in seed size leads to larger seedlings and higher relative oil content of the seeds. Genetic analyses indicate that KLU acts independently of other tested maternal factors that influence integument cell proliferation. Thus, the level of KLU-dependent growth factor signaling determines size in ovules and seeds, suggesting this pathway as a target for crop improvement. |
4楼2010-04-09 02:21:41
zwdbordeaux
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Key seed size gene identified 5th November 2009 Scientists from the John Innes Centre in Norwich, UK and the University of Freiburg in Germany have uncovered a gene in plants that is responsible for controlling the size of seeds, which could lead to ways of improving crops to help ensure food security in the future. Increasing seed or grain size has been key in the domestication of the crops used in modern agriculture, and with a growing world population, further increasing the yield of crops is one goal of agricultural research. Michael Lenhard, funded by the Biotechnology and Biological Sciences Research Council (BBSRC), has identified a gene in the model plant Arabidopsis that determines overall seed size, and is now investigating how this could be used to for the improvement of crops. Publishing in the Proceedings of the National Academy of Sciences, the team from the John Innes Centre, an institute of the BBSRC, demonstrated that the gene acts locally at the base of the growing seed. It produces an as yet unidentified mobile growth signal that determines final seed size. If the gene is turned off, smaller seeds are produced, but crucially if the gene is turned on at a higher level than normal, seeds a third larger in size and weight are produced. This is the first time such a reciprocal effect on seed size has been observed, and points to the fundamental importance of this gene in plant development. More work is now needed before this research can be applied to crop plants. One effect of increasing the seed size in the experimental plants was to decrease the total number of seeds produced, so there was no overall increase in yield. The scientists did notice an increase in the relative oil content of the larger seeds, so the effects of altering this gene in oil seed rape is currently being investigated. Unravelling this gene’s role in determining the final seed size will also be important for other strategies for increasing yield, an example of how fundamental plant science can inform and drive efforts to ensure food security. Professor Mike Bevan, Acting Director of the John Innes Centre, said “This work shows how JIC's focus on understanding the mechanisms controlling plant growth can have immediate useful application for crop improvement.” Contacts: JIC Press Office: Andrew Chapple, Tel: 01603 251490, email: andrew.chapple@bbsrc.ac.uk Zoe Dunford, Tel: 01603 255111, email: zoe.dunford@bbsrc.ac.uk Notes to Editors: Reference: Local maternal control of seed size by KLUH/CYP78A5-dependent growth Signalling, PNAS,Published online before print November 5, 2009, doi: 10.1073/pnas.0907024106 Funding: BBSRC David Phillips Fellowship About the JIC The John Innes Centre, www.jic.ac.uk, is an independent, world-leading research centre in plant and microbial sciences with over 800 staff. JIC is based on Norwich Research Park and carries out high quality fundamental, strategic and applied research to understand how plants and microbes work at the molecular, cellular and genetic levels. The JIC also trains scientists and students, collaborates with many other research laboratories and communicates its science to end-users and the general public. The JIC is grant-aided by the Biotechnology and Biological Sciences Research Council. About BBSRC The Biotechnology and Biological Sciences Research Council (BBSRC) is the UK funding agency for research in the life sciences. Sponsored by Government, BBSRC annually invests around £450 million in a wide range of research that makes a significant contribution to the quality of life for UK citizens and supports a number of important industrial stakeholders including the agriculture, food, chemical, healthcare and pharmaceutical sectors. BBSRC carries out its mission by funding internationally competitive research, providing training in the biosciences, fostering opportunities for knowledge transfer and innovation and promoting interaction with the public and other stakeholders on issues of scientific interest in universities, centres and institutes. The Babraham Institute, Institute for Animal Health, Institute of Food Research, John Innes Centre and Rothamsted Research are Institutes of BBSRC. The Institutes conduct long-term, mission-oriented research using specialist facilities. They have strong interactions with industry, Government departments and other end-users of their research. www.bbsrc.ac.uk/ |
5楼2010-04-09 02:25:13
6楼2010-04-09 21:39:59
yangszh
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7楼2010-04-20 09:44:16