School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, Virginia, USA.
Plant Physiol. 2022 Jun 1;189(2):687-702. doi: 10.1093/plphys/kiac106.
Cuscuta campestris is an obligate parasitic plant that requires a host to complete its life cycle. Parasite-host connections occur via a haustorium, a unique organ that acts as a bridge for the uptake of water, nutrients, and macromolecules. Research on Cuscuta is often complicated by host influences, but comparable systems for growing the parasite in the absence of a host do not exist. We developed an axenic method to grow C. campestris on an artificial host system (AHS). We evaluated the effects of nutrients and phytohormones on parasite haustoria development and growth. Haustorium morphology and gene expression were also characterized. The AHS consists of an inert, fibrous stick that mimics a host stem, wicking water and nutrients to the parasite. It enables C. campestris to exhibit a parasitic habit and develop through all stages of its life cycle, including production of new shoots and viable seeds. The phytohormones 1-naphthaleneacetic acid and 6-benzylaminopurine affect haustoria morphology and increase parasite fresh weight and biomass. Unigene expression in AHS haustoria reflects processes similar to those in haustoria on living host plants. The AHS is a methodological improvement for studying Cuscuta biology by avoiding specific host effects on the parasite and giving researchers full control of the parasite environment.
菟丝子是一种专性寄生植物，需要宿主才能完成其生命周期。寄生与宿主的连接是通过吸器来实现的，吸器是一种独特的器官，充当了水分、养分和生物大分子摄取的桥梁。菟丝子的研究常常受到宿主影响的困扰，但不存在没有宿主时生长寄生虫的可比系统。我们开发了一种在人工宿主系统（AHS）上生长菟丝子的无菌方法。我们评估了养分和植物激素对寄生虫吸器发育和生长的影响。还对吸器形态和基因表达进行了表征。AHS 由惰性纤维状棒组成，模拟宿主茎，将水分和养分吸到寄生虫上。它使菟丝子能够表现出寄生习性，并经历其生命周期的所有阶段，包括产生新的芽和有活力的种子。植物激素 1-萘乙酸和 6-苄基氨基嘌呤影响吸器形态，并增加寄生虫的鲜重和生物量。AHS 吸器中的基因表达反映了与活体宿主植物上吸器相似的过程。AHS 是研究菟丝子生物学的方法改进，避免了宿主对寄生虫的特定影响，并使研究人员能够完全控制寄生虫的环境。
