（圖片來(lái)源：Max Planck Institute for Developmental Biology）
德國(guó),、瑞士等國(guó)科學(xué)家近日研究發(fā)現(xiàn),，microRNA能夠調(diào)控植物的生長(zhǎng)和老化過(guò)程。這是首次闡明植物生長(zhǎng)和老化的拮抗調(diào)控機(jī)制,。相關(guān)論文發(fā)表在《PloS生物學(xué)》（PLoS Biology）上,。
microRNA是短小、單鏈的基因片段,，它們能調(diào)控其它的基因,。microRNA綁定在遺傳材料的補(bǔ)充序列上，從而阻止這些序列被“閱讀”及發(fā)揮作用,。在植物中,，microRNA主要抑制其它的調(diào)節(jié)因子，即所謂的轉(zhuǎn)錄因子,。這些因子能通過(guò)綁定到DNA片段開啟或關(guān)閉基因,，從而形成過(guò)多或過(guò)少的蛋白質(zhì)。因?yàn)榈鞍踪|(zhì)控制著代謝過(guò)程,，所以如果失衡就會(huì)導(dǎo)致植物或多或少的可見(jiàn)變化,。
在最新的研究中，德國(guó)馬普發(fā)育生物學(xué)研究所的Detlef Weigel和瑞士等國(guó)的同行調(diào)查了TCP家族的轉(zhuǎn)錄因子對(duì)于模式植物擬南芥的生長(zhǎng)和老化的作用,。這些轉(zhuǎn)錄因子由miR319調(diào)控,。
結(jié)合生物化學(xué)和遺傳分析，研究人員發(fā)現(xiàn),，這些轉(zhuǎn)錄因子不僅影響葉子的生長(zhǎng),，而且還調(diào)控對(duì)于植物激素茉莉酮酸形成必不可少的基因,。植物中miR319的含量越高，轉(zhuǎn)錄因子的數(shù)量就越少,，這就導(dǎo)致茉莉酮酸合成量更少,。而含很少量茉莉酮酸的植物老化速度更慢。這一過(guò)程可通過(guò)用激素處理植物阻斷,。
Weigel說(shuō)：“我們的研究顯示,，由miR319調(diào)控的轉(zhuǎn)錄因子對(duì)于植物的生長(zhǎng)施加了消極作用，而且導(dǎo)致植物過(guò)早老化,。此次發(fā)現(xiàn)的機(jī)制是植物遺傳調(diào)節(jié)關(guān)系研究的一個(gè)里程碑,。只有當(dāng)更好地理解了這些過(guò)程，我們才能生產(chǎn)出具有特殊性能的植物,。”（生物谷Bioon.com）
生物谷推薦原始出處：
PLoS Biology,，doi:10.1371/journal.pbio.0060230，Carla Schommer,，Detlef Weigel
Control of Jasmonate Biosynthesis and Senescence by miR319 Targets
Carla Schommer, Javier F. Palatnik, Pooja Aggarwal, Aurore Chételat, Pilar Cubas, Edward E. Farmer, Utpal Nath, Detlef Weigel
Considerable progress has been made in identifying the targets of plant microRNAs, many of which regulate the stability or translation of mRNAs that encode transcription factors involved in development. In most cases, it is unknown, however, which immediate transcriptional targets mediate downstream effects of the microRNA-regulated transcription factors. We identified a new process controlled by the miR319-regulated clade of TCP(TEOSINTE BRANCHED/CYCLOIDEA/PCF) transcription factor genes. In contrast to other miRNA targets, several of which modulate hormone responses, TCPs control biosynthesis of the hormone jasmonic acid. Furthermore, we demonstrate a previously unrecognized effect of TCPs on leaf senescence, a process in which jasmonic acid has been proposed to be a critical regulator. We propose that miR319-controlled TCP transcription factors coordinate two sequential processes in leaf development: leaf growth, which they negatively regulate, and leaf senescence, which they positively regulate.
