吸器是寄生植物的特征器官及其从寄主获取养分的唯一通道。吸器的数量和分化水平直接影响寄生关系的建立。先前关于吸器发生仅限于对源自寄主诱导信号的研究，而对其它因素的影响则知之甚少。我们近期发现，接种丛枝菌根（AM）真菌可抑制根部半寄生植物三色马先蒿的吸器形成。这是迄今发现的首例对寄生植物吸器发生有直接抑制效应的生物现象。三色马先蒿可与AM真菌建立共生关系，且可在无寄主条件下生长并产生吸器，是研究AM真菌直接影响根寄生植物吸器形成过程的理想材料。为进一步阐释AM真菌对吸器形成的抑制现象及相关调控，本项目拟以6种AM真菌为接种材料，通过温室控制条件下的菌种回接实验，分析不同AM真菌种类对三色马先蒿吸器形成的影响；并通过设置不同氮、磷水平及氮磷配比，研究不同氮磷营养水平下AM真菌对三色马先蒿吸器形成的影响。该研究可为了解根寄生植物的吸器发生和调控过程提供新视角，并为根寄生杂草的生物防治提供新思路。

Haustoria are exclusive organs of parasitic plants responsible for host attachment and nutrient transfer. Initiation and proper differentiation of haustoria is essential to successful plant parasitism. Investigations have been focused on inducing effects of host plants on initiation and differentiation of haustoria. Little is known about effects of other factors on haustorium formation in parasitic plants. Recently we found that inoculation with arbuscular mycorrhizal (AM) fungi strongly suppressed haustorium initiation and differentiation in root-hemiparasitic Pedicularis tricolor, which is the first report so far regarding repressive effects of a living organism on haustorium formation in parasitic plants. Being able to form AM association with AM fungi as well as to grow and produce haustoria in the absence of a host plant, P. tricolor is an ideal plant system for studying direct influence of AM fungi on haustorium formation in root parasitic plants. To gain a better knowledge of the repressive effects of AM fungi on haustorium formation and relevant regulation processes, we aim to study the effects of different AM fungal species on haustorium formation in P. tricolor under greenhouse conditions, using six AM fungal species isolated from habitat soil of the hemiparasite. In addition, we will test the influence of AM fungal inoculation on haustorium formation in P. tricolor under different nitrogen (N) and phosphorus (P) conditions, by supplying different levels of N, P, and N:P ratios. Knowledge gained will open a new perspective for a better understanding of regulation of haustorium formation in root parasitic plants, and may provide clues for development of new biocontrol strategies in the management of parasitic weeds.