Multilayered Organization of Jasmonate Signalling in the Regulation of Root Growth.
Multilayered Organization of Jasmonate Signalling in the Regulation of Root Growth.
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DOI：
10.1371/journal.pgen.1005300
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发表时间：
2015-06
期刊：
影响因子：
4.5
通讯作者：
Farmer EE
中科院分区：
文献类型：
--
作者：
Gasperini D;Chételat A;Acosta IF;Goossens J;Pauwels L;Goossens A;Dreos R;Alfonso E;Farmer EE
物理损伤会严重影响植物生长，减少距离伤口一定距离的发育器官的生物量。以前在叶子中研究的这些效应需要茉莉酸（JA）信号的激活。利用一种新的试验，涉及重复子叶损伤拟南芥幼苗，我们发现了JA抑制细胞分裂和根伸长的功能。调控JA信号成分，然后操纵描绘其对根生长的相对影响。分离到一个新的转录因子突变体myc 2 - 322 B。在体外转录测定和全植物的方法表明，myc 2 - 322 B是一个剂量依赖性的功能获得突变体，可以放大JA生长反应。此外，myc 2 - 322 B表现出极端敏感JA，完全抑制根伸长。该突变微弱地降低了未受损植物的根生长，但是，当上游负调节因子NINJA被遗传去除时，myc 2 - 322 B通过其对细胞分裂和细胞伸长的影响而有力地抑制了根生长。此外，在JA缺陷突变体的背景下，ninja 1 myc 2 - 322 B仍然抑制根伸长，这表明它是可能的，以产生JA反应，在缺乏JA。我们表明，NINJA形成一个广泛表达的监管层，需要抑制JA信号在根尖生长在基础条件下。相比之下，MYC 2、MYC 3和MYC 4显示细胞层特异性定位，并且MYC 3和MYC 4在相互排斥的区域中表达。在自然界中，生长的根系在土壤渗透过程中可能会受到恒定的机械应力，这可能导致JA的产生和随后对生长的不利影响。我们的数据揭示了不同的负调控层，包括NINJA依赖和独立的机制，抑制JA反应，使正常的根生长。这项工作的机制见解强调了将JA信号传导组分映射到特定细胞类型的重要性，以便理解和潜在地设计物理损伤后的生长减少。植物发育的研究通常在没有物理损伤的情况下进行。然而，在自然界中，生物和非生物伤害对植物器官的损害是常见的。在这些条件下，在非胁迫营养组织中具有低活性的茉莉酸途径对细胞分裂和伸长施加其活性。这种依赖茉莉酸的生长限制可以强烈地影响植物生产力。以根为模型，我们表明，这是可能的操纵调控层在茉莉酸信号，使细胞分裂和细胞伸长可以受到不同的约束。这种方法可能会导致未来改变器官生长的策略。此外，在这项研究中，我们确定了一个新的突变体的茉莉酸途径的关键调节。这种突变体产生了茉莉酸信号传导的正调节因子，它非常活跃，以至于我们能够证明激素合成可以完全与激素反应解耦，这表明了修改潜在农艺学重要性状的方法。
Physical damage can strongly affect plant growth, reducing the biomass of developing organs situated at a distance from wounds. These effects, previously studied in leaves, require the activation of jasmonate (JA) signalling. Using a novel assay involving repetitive cotyledon wounding in Arabidopsis seedlings, we uncovered a function of JA in suppressing cell division and elongation in roots. Regulatory JA signalling components were then manipulated to delineate their relative impacts on root growth. The new transcription factor mutant myc2-322B was isolated. In vitro transcription assays and whole-plant approaches revealed that myc2-322B is a dosage-dependent gain-of-function mutant that can amplify JA growth responses. Moreover, myc2-322B displayed extreme hypersensitivity to JA that totally suppressed root elongation. The mutation weakly reduced root growth in undamaged plants but, when the upstream negative regulator NINJA was genetically removed, myc2-322B powerfully repressed root growth through its effects on cell division and cell elongation. Furthermore, in a JA-deficient mutant background, ninja1 myc2-322B still repressed root elongation, indicating that it is possible to generate JA-responses in the absence of JA. We show that NINJA forms a broadly expressed regulatory layer that is required to inhibit JA signalling in the apex of roots grown under basal conditions. By contrast, MYC2, MYC3 and MYC4 displayed cell layer-specific localisations and MYC3 and MYC4 were expressed in mutually exclusive regions. In nature, growing roots are likely subjected to constant mechanical stress during soil penetration that could lead to JA production and subsequent detrimental effects on growth. Our data reveal how distinct negative regulatory layers, including both NINJA-dependent and -independent mechanisms, restrain JA responses to allow normal root growth. Mechanistic insights from this work underline the importance of mapping JA signalling components to specific cell types in order to understand and potentially engineer the growth reduction that follows physical damage. The study of plant development is generally carried out in the absence of physical injury. However, damage to plant organs through biotic and abiotic insult is common in nature. Under these conditions the jasmonate pathway that has a low activity in unstressed vegetative tissues imposes its activity on cell division and elongation. Such jasmonate-dependent growth restriction can strongly impact plant productivity. Taking roots as a model, we show that it is possible to manipulate regulatory layers in jasmonate signalling such that cell division and cell elongation can be constrained differently. This approach may lead to future strategies to alter organ growth. Moreover, during this study we identified a novel mutant in a key regulator of the jasmonate pathway. This mutant generated a positive regulator of jasmonate signalling that was so active that we were able to show that hormone synthesis can be completely uncoupled from hormone responses, suggesting ways to modify traits of potential agronomic importance.