• D14 and KAI2 receptors enable plants to distinguish between strigolactones (SLs) and karrikins (KARs), respectively, in order to trigger appropriate environmental and developmental responses. Both receptors are related to the regulation of arbuscular mycorrhiza (AM) formation and are members of the RsbQ‐like family of α,β‐hydrolases. DLK2 proteins, whose function remains unknown, constitute a third clade from the RsbQ‐like protein family. We investigated whether the tomato SlDLK2 is a new regulatory component in the AM symbiosis.
• Genetic approaches were conducted to analyze SlDLK2 expression and to understand SlDLK2 function in AM symbiosis.
• We show that SlDLK2 expression in roots is AM‐dependent and is associated with cells containing arbuscules. SlDLK2 ectopic expression arrests arbuscule branching and downregulates AM‐responsive genes, even in the absence of symbiosis; while the opposite effect was observed upon SlDLK2 silencing. Moreover, SlDLK2 overexpression in Medicago truncatula roots showed the same altered phenotype observed in tomato roots. Interestingly, SlDLK2 interacts with DELLA, a protein that regulates arbuscule formation/degradation in AM roots.
• We propose that SlDLK2 is a new component of the complex plant‐mediated mechanism regulating the life cycle of arbuscules in AM symbiosis.

中文翻译：

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DLK2在丛枝菌根共生期间调节丛枝菌丝的分支。

• D14和KAI2受体使植物能够分别区分strigolactones（SLs）和karrikins（KARs），从而触发适当的环境和发育反应。这两种受体都与丛枝菌根（AM）形成的调节有关，并且是RsbQ样α，β-水解酶家族的成员。未知功能的DLK2蛋白构成了RsbQ样蛋白家族的第三条线索。我们调查了番茄SlDLK2是否是AM共生中的新调控成分。
• 进行了遗传方法来分析SlDLK2表达并了解SlDLK2在AM共生中的功能。
• 我们显示根中的SlDLK2表达是AM依赖性的，并且与包含丛枝的细胞相关。即使没有共生，SlDLK2异位表达也能阻止丛枝分支并下调AM反应基因。而在SlDLK2沉默时观察到相反的作用。此外，Medi藜苜蓿根中的SlDLK2过表达显示出在番茄根中观察到的相同的表型改变。有趣的是，SlDLK2与DELLA相互作用，该蛋白调节AM根中丛枝的形成/降解。
• 我们认为，SlDLK2是调节AM共生中丛枝的生命周期的复杂植物介导机制的新组成部分。