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【bio-news】microRNAs可延长植物寿命
ScienceDaily (Sep. 23, 2008) — Molecular biologists from Tuebingen, Germany, have discovered how the growth of leaves and the aging process of plants are coordinated.
Plants that grow more slowly stay fresh longer. Scientists at the Max Planck Institute for Developmental Biology in Tuebingen, Germany, have shown that certain small sections of genes, so-called microRNAs, coordinate growth and aging processes in plants.
These microRNAs inhibit certain regulators, known as TCP transcription factors. These transcription factors in turn influence the production of jasmonic acid, a plant hormone. The higher the number of microRNAs present, the lower the number of transcription factors that are active, and the smaller the amount of jasmonic acid, which is produced by the plant.
The plant therefore ages more slowly, as this hormone is important for the plant’s aging processes. Since the quantity of microRNAs in the plants can be controlled by genetic methods, it may be possible in future to cultivate plants that live longer and grow faster. (PLoS Biology, Sept. 22, 2008)
MicroRNAs are short, single-strand sections of genes that regulate other genes. They do this by binding to complementary sections of the genetic material, thus preventing them from being read and implemented in genetic products. In plants, microRNAs mainly inhibit other regulators, so-called transcription factors. These factors can switch genes on or off by binding to DNA sections, thus activating or blocking them so that either too many or too few proteins are formed. Since proteins control metabolic processes, an imbalance leads to more or less clearly visible changes to the plant.
The scientists in Detlef Weigel’s department at the Max Planck Institute for Developmental Biology have investigated the effects that the transcription factors of the TCP family have on the growth and aging of the model plant Arabidopsis thaliana. These transcription factors are regulated by the microRNA miR319.
It was already known that miR319-regulated transcription factors affect the growth of leaves. Using a combination of biochemical and genetic analyses, the researchers have now discovered that the transcription factors also regulate those genes that are essential for the formation of the plant hormone jasmonic acid. The higher the quantity of the microRNA miR319 present in the plant, the lower the number of transcription factors that are produced, and hence the smaller the amount of jasmonic acid, which can be synthesized. These plants have longer growth periods and age more slowly than plants that contain less miR319 and therefore have a shorter growth period but die off sooner.
“Our studies show that the transcription factors, which are regulated by the microRNA miR319, exert a negative influence on the growth of plants, and also lead to premature aging,” says Detlef Weigel. The mechanism discovered here is a further milestone in the attempt to explain the relationships of genetic regulation in plants. “Only when we have a better understanding of these processes will we be able to produce plants that have particularly desired properties,” says biologist Weigel. 本人认领翻译，48小时未提交则请其他战友自由认领。 发现延长植物寿命的公式
科学日报（2008年9月23日）
德国蒂宾根大学的分子生物学家们发现，叶子的伸长过程和植物的衰老过程是同步的。
生长缓慢的植物可以保鲜更长时间。德国蒂宾根大学马克斯. 普朗克发育生物学研究所的科学家证明，某些基因小片段（microRNA）和植物的长成、衰老过程相关。
这些microRNAs抑制某几个TCP转录调控因子。这些转录因子转而影响茉莉酸（一种植物激素）的产生。microRNAs表达量越高，被激活的转录因子就越少，植物合成茉莉酸就越少。
因为茉莉酸是植物衰老过程中一种重要的激素，所以植物的衰老就会更加缓慢。因为植物中的microRNAs水平可以用遗传学方法控制，所以这一发现使人们在未来培育活得更长、长得更快的植物成为可能。（PloS Biology,2008年9月22日）
MicroRNAs是一类调节其他基因表达的小片段、单链基因。它们遗传物质的互补区域，进而阻止遗传信息的读取和遗传产物的生成。在植物中，microRNAs主要干扰转录因子。这些因子结合DNA，并激活或阻断基因来控制蛋白质的形成。转录因子是基因的开关。由于蛋白质控制着代谢过程，因此蛋白质表达的变化或多或少会导致植物一些可见的变化。
马克斯. 普朗克发育生物学研究所戴特列夫.魏格尔实验室的科学家已经观察到，TCP家族转录因子对模式植物拟南芥生长和衰老的影响。这些转录因子被microRNA miR319调控。
过去认为，mi319调节的转录因子影响叶子的生长。通过生物化学和遗传学相结合的方面，现在研究者发现这些转录因子也调控植物茉莉酸途径关键基因。microRNAs水平越多，转录因子的数量就越少，植物合成的茉莉酸就越少。这样的植物生长期更长，衰老更慢；而那些miR319含量少的植物，生长期短，而且死得更快。
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作者:admin@医学,生命科学 2011-05-01 17:11
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