先看到这则科学网新闻，感觉有趣，就点击链接去看原文。其中有些地方不是很懂。请科学网上的专家做深入的阐释。如果海南的以及武汉的两位刘老师能给予阐释，将非常专业和精彩。 PNAS：研究揭示剪枝促植物生长的深层原理 剪去一些枝干反而促进植物生长是园艺学中常见现象。一项最新研究揭示了其中的深层原理。 英国约克大学日前发布新闻公报说，该校研究人员领导的一个国际小组在新一期美国《国家科学院院刊》（ PNAS ）发表了相关论文。 论文解释说， 积极生长的 植物分枝 都会释放一种生长素到主干中，一个分枝想要生长， 在主干中就必须有它自己的生长素，如果主干中已有大量生长素，则新分枝产生的生长素就难以在其中取得一席之地，其生长将受抑制。例如，植物顶端的主枝通常较粗大，这是因为它最早生长，所释放的生长素占据了主导地位 。 研究人员说，各分枝同时还会分泌其他激素，限制别的生长素在主干中传播，从而加剧竞争的激烈程度。园丁通过剪去主枝等方法让这种竞争趋于平衡，使果树得以长出更多分枝，结出更多果实。 http://www.sciencenet.cn/htmlnews/2009/9/223619.shtm Explaining why pruning encourages plants to thrive Posted on 21 September 2009 Scientists have shown that the main shoot dominates a plants growth principally because it was there first, rather than due to its position at the top of the plant. Collaborating teams from the University of York in the UK and the University of Calgary in Canada combined their expertise in molecular genetics and computational modelling to make a significant discovery that helps explain why pruning encourages plants to thrive. Understanding of the action and interaction of these hormones can inform horticultural practices aimed at changing branching patterns in diverse crops. The research was funded by the Biotechnology and Biological Sciences Research Council (BBSRC) and the Natural Sciences and Engineering Research Council of Canada (NSERC). Led by Professors Ottoline Leyser and Przemyslaw Prusinkiewicz and published by the journal PNAS, the research showed that all shoot tips on a plant can influence each others growth. Professor Leyser, of the University of Yorks Department of Biology, said: It is well known that the main growing shoot of a plant can inhibit the growth of the shoots below thats why we prune to encourage growth of branches. What we are interested in is exactly how the main shoot can exert this effect. It has been known since the 1930s that the plant hormone auxin is released by the plants actively growing tip and is transported down the main stem where it has an indirect effect on buds to inhibit branching. There are a number of ways in which the hormone exerts this effect and we have discovered a new path by which it works. The research suggests that for a shoot tip to be active , it must be able to export auxin into the main stem. But if substantial amounts of auxin already exist in the main stem, export from an additional shoot tip cannot be established . Professor Leyser said: Using this mechanism, all the shoot tips on a plant compete with each other, so that tips both above and below can influence each other's growth. This allows the strongest branches to grow the most vigorously, wherever they may be on the plant. The main shoot dominates mostly because it was there first, rather than because of its position at the apex of the plant. The teams went on to show that the recently discovered plant hormone, strigolactone, works at least in part by making it harder to establish new auxin transport pathways from shoot tips, strengthening the competition between auxin sources and reducing branching. http://www.york.ac.uk/news-and-events/news/2009/pruning-plants/
标签: 专家
