Cassorrhizal Colonization: A Hostless Framework for Mycorrhizal Symbiotic Induction

This preprint documents an original experimental framework for inducing mycorrhizal symbiotic behavior in ectomycorrhizal fungi under entirely hostless laboratory conditions. The work introduces the novel term Cassorrhizal — defined as a state of false colonization where fungal mycelium is chemically or physically lured into a symbiotic response by a non-living, deceptive, or non-existent root structure — and describes the J160 media series developed to replicate the chemical, mechanical, and osmotic environment of a living root without one being present. The framework covers the multi-role chemistry of a purpose-formulated low acyl gellan gum matrix as a root tissue analog, a pH-buffered TCA cycle entry point carbon system, hemicellulose signaling compounds, osmotic turgor management, and flavonoid-mediated pre-symbiotic effector induction via rutin hydrothermal conversion. The experimental isolate is a suspected Lactarius rubidus, though the framework is designed to apply broadly to ectomycorrhizal species. The target phenotype is Hartig net formation or attempted formation in the absence of a living host.本预印本报道了一套原创性实验框架，可在完全无宿主的实验室条件下诱导外生菌根真菌（ectomycorrhizal fungi）产生菌根共生行为。本研究提出了全新术语假共生定植（Cassorrhizal），其定义为：一种虚假定植状态，即真菌菌丝体通过非活体、欺骗性或虚构的根系结构，以化学或物理方式诱导自身产生共生响应；同时本研究描述了专为复刻活体根系的化学、机械与渗透环境而开发的J160系列培养基。 该实验框架涵盖了一套多组分化学体系：包括用作根系组织类似物的专门配制低酰基结冷胶基质（low acyl gellan gum matrix）、经pH缓冲的三羧酸（TCA）循环起始碳源系统、半纤维素信号化合物、渗透膨压调控机制，以及通过芦丁水热转化实现的类黄酮介导的共生前效应因子诱导。本次实验所用的分离菌株经初步鉴定疑似为红乳菇（Lactarius rubidus），但该框架的设计目标为可广泛适配各类外生菌根物种，其目标表型为在无活体宿主的条件下形成或尝试形成哈蒂氏网（Hartig net）。