Abstract：
Root hair is regarded as a pivotal complementary survival tactic for mycorrhizal plant like Abies beshanzuensis when symbiosis is disrupted. Relatively little is known about the mechanism underlying root hair morphogenesis in plant species that are strongly dependent on mycorrhizal symbiosis. Many of these species are endangered, and this knowledge is critical for ensuring their survival. Here, a MYB6/bHLH13-sucrose synthase 2 (AbSUS2) module was newly identified and characterized in A. beshanzuensis using bioinformatics, histochemistry, molecular biology, and transgenesis. Functional, expression pattern, and localization analysis showed that AbSUS2 participated in sucrose synthesis and was involved in root hair initiation in A. beshanzuensis. Additionally, the major enzymatic product of AbSUS2 was found to suppress root hair initiation in vitro. Our data further showed that a complex involving the transcription factors AbMYB6 and AbbHLH13 directly interacted with the promoter of AbSUS2 and strengthened its expression, thereby inhibiting root hair initiation in response to exogenous sucrose. Our findings offer novel insights into how root hair morphogenesis is regulated in mycorrhizal plants and also provide a new strategy for the preservation of endangered mycorrhizal plant species.
摘要：
当共生关系被破坏时，根毛被认为是像冷杉这样的菌根植物的关键互补生存策略。对于强烈依赖菌根共生的植物物种中根毛形态发生的机制知之甚少。这些物种中的许多都濒临灭绝，这些知识对于确保他们的生存至关重要。这里,MYB6/bHLH13-蔗糖合成酶2（AbSUS2）模块是新鉴定和表征在A.beshanzuensis使用生物信息学，组织化学,分子生物学,和转基因。Functional,表达模式,和定位分析表明，AbSUS2参与了蔗糖的合成，并参与了A.beshanzuensis的根毛萌生。此外,发现AbSUS2的主要酶产物在体外抑制根毛引发。我们的数据进一步表明，涉及转录因子AbMYB6和AbbHLH13的复合物与AbSUS2的启动子直接相互作用并增强其表达，从而抑制根毛对外源蔗糖的反应。我们的发现为根毛形态发生在菌根植物中的调控提供了新的见解，也为保护濒危菌根植物物种提供了新策略。
