A rhizobox experiment was carried out, using boxes each separated into two compartments in the middle with nylon net and planted with aerobic rice and/or watermelon, both inoculated with Glomus etunicatum of arbuscular mycorrhizal fungi (abbreviated as AM fungus), to investigate formation of arbuscular mycorrhizal hyphal links between the roots of the two plants, and their effects on expression of OsPT11, phosphate transporter in rice, and uptake of phosphorus. Results showed that when neither aerobic rice nor watermelon was inoculated with AM fungus, no mycorrhiza colonized and no expression of OsPT11 was observed either in rice roots; (2) When the watermelon compartment was incubated, the hyphal links formed between aerobic rice and watermelon induced colonization of mycorrhiza on rice and expression of OsPT11 in the root system of rice; (3) Inoculation either directly or indirectly through hyphal links displayed the same effect on colonization of mycorrhiza in aerobic rice and watermelon, making the colonization rate over 80% and over 70%, respectively; and (4) In the aerobic rice/watermelon interplanting system, inoculation significantly increased availability of phosphorus in the rhizosphere of both aerobic rice and watermelon as compared to control, and the content of total phosphorus decreased in the shoots of rice, but increased in the shoots of watermelon.