Journal of Environmental Sciences 2011, 23(6) 968–974 Arbuscular mycorrhizal fungi alter the response of growth and nutrient uptake of snap bean (Phaseolus vulgaris L.) to O 3 Shuguang Wang 1 , Zhaozhong Feng 2, ∗ , Xiaoke Wang 2,3,∗ , Wenliang Gong 1 1. Department of Environmental Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China. E-mail: shgwang2002@yahoo.com.cn 2. State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China 3. Beijing Urban Ecosystem Research Station, Beijing 100085, China Received 22 June 2010; revised 12 September 2010; accepted 20 September 2010 Abstract The effects of arbuscular mycorrhizal fungi (AMF) Glomus mosseae on the responses to elevated O 3 in growth and nutrition of snap bean (Phaseolus vulgaris L. cv Guangzhouyuan) were investigated. Exposure was conducted in growth chambers by using three O 3 concentrations (20 (CF), 80 (CFO1) and 120 nL/L (CFO2); 8 hr/day for 75 days). Results showed that elevated O 3 slightly impacted overall mycorrhizal colonization, but significantly decreased the proportional frequency of hypha and increased the proportional frequency of spores and vesicles, suggesting that O 3 had significant effects on mycorrhizal structure. Elevated O 3 significantly decreased yield, dry mass and nutrient contents (N, P, K, Ca and Mg) in both non-mycorrhizal and mycorrhizal plants. However, significant interactive effects were found in most variables due to that the reduction by O 3 in the mycorrhizal plants was less than that in the non-mycorrhizal plants. Additionally, AMF increased the concentrations of N, P, Ca, and Mg in shoot and root. It can be concluded that AMF alleviated detrimental effects of increasing O 3 on host plant through improving plant nutrition and growth. Key words: arbuscular mycorrhizal fungi; nutrition status; mycorrhizal colonization; elevated O 3 ; snap bean DOI: 10.1016/S1001-0742(10)60503-7 Citation: Wang S G, Feng Z Z, Wang X K, Gong W L, 2011. Arbuscular mycorrhizal fungi alter the response of growth and nutrient uptake of snap bean (Phaseolus vulgaris L.) to O 3 . Journal of Environmental Sciences, 23(6): 968–974 Introduction Tropospheric ozone (O 3 ), the most important secondary air pollutant, is regarded to be one of the most potent and pervasive phytotoxic gaseous pollutants in the at- mosphere (Krupa et al., 2001). Although the increasing trend in O 3 concentration has slowed down or has been decreasing in the USA and Europe (IPCC, 2007), surface O 3 concentration in peri-urban areas of East Asia is still rising due to rapid industrialization and urbanization (The Royal Society, 2008). In China, the means of daily O 3 concentration has been reported to reach more than 150 nL/L in some developed regions, such as the Beijing- Tianjin Region, Yangtze Delta, and Pearl Delta (Shao et al., 2006; Wang et al., 2007a), where ambient O 3 concentration has been shown to have a significantly negative impact on crop yields (Feng et al., 2003; Wang et al., 2007b). The most obvious effect of ozone on vegetation is an accelerated senescence, accompanied by a decrease of photosynthetic rate, alteration of carbon allocation and biomass partitioning, yield loss, and seed quality alteration * Corresponding author. E-mail: fzz@rcees.ac.cn (Feng Z Z); wangxk@rcees.ac.cn (Wang X K) (Scebba et al., 2006; Feng et al., 2008, 2010; Feng and Kobayashi, 2009). These detrimental effects may attribute partly to the deterioration of plant nutrition status in- duced by O 3 stress. However, information on the effects of elevated O 3 on macronutrients other than nitrogen in herbaceous species is scarce and inconsistent (Tingey et al., 1986; Heagle et al., 1998; Fangmeier et al., 2002; Piikki et al., 2007). For example, O 3 exposure decreased Ca and Mg concentrations in the leaves of snap bean (Phaseolus vulgaris L.), while increased foliar concentration of Ca in soybean (Glycine max L. Merr.), and slightly changed K and P concentrations in the leaves of both crops (Tingey et al., 1986; Heagle et al., 1998). Arbuscular mycorrhiza (AM) symbiosis is the most widespread mycorrhizal association type with plants that have true roots (Read et al., 2000). About 80%–90% land plants in natural, agricultural and forest ecosystems live in symbiosis with AM (Brundrett, 2002). Their effects were well-documented on the enhancement of the phosphorus uptake, and on other macro- and micro-elements, in stress- ful environment (Berta et al., 1995). However, few studies have addressed the influence of AMF on plant response to increasing O 3 . Among the few studies, Brewer and