Original article Differential growth response of Curculigo orchioides to native arbuscular mycorrhizal fungal (AMF) communities varying in number and fungal components Deepika Sharma, Rupam Kapoor * , A.K. Bhatnagar Environmental Biology Laboratory, Department of Botany, University of Delhi, Delhi 110 007, India article info Article history: Received 21 October 2008 Received in revised form 13 March 2009 Accepted 7 April 2009 Available online 3 May 2009 Handling editor: Kristina Lindstro ¨m Keywords: Arbuscular mycorrhiza AMF species diversity Curculigo orchioides Mixed consortia Soil pH Species richness Variable plant response abstract The study reports diversity of arbuscular mycorrhizal fungal (AMF) species in the rhizosphere of an endangered anticancerous herb – Curculigo orchioides Gaertn. in its natural habitat. A total of 18 species of AMF, belonging to three genera (Acaulospora, Glomus and Gigaspora) were recorded, with Glomus microcarpum being the most abundant species type. The AMF species composition across the study sites appeared to be influenced by soil pH rather than soil P and vegetation. Acaulospora laevis spores were restricted to sites where the soil pH was acidic. The effectiveness of these native AMF species on growth performance of C. orchioides plants was compared under experimental conditions. In general, the mycorrhizal plants were superior in most of the evaluated parameters, but the extent to which the growth of mycorrhizal plants was influenced varied with the inocula used. The plants inoculated with mixed consortia containing maximum AMF species richness exhibited improved growth in comparison to consortia containing lower AMF diversity and monospecies cultures. The variable plant responses observed with any two consortia having same species richness in the present study could be due to variable component AMF species and their relative abundance. These results emphasize the need to protect the below-ground diversity of AMF and recommend their usage for restoration practices. Ó 2009 Elsevier Masson SAS. All rights reserved. 1. Introduction Arbuscular mycorrhizal fungi (AMF) are major components of the rhizosphere microflora in natural ecosystems and are essential for sustainable plant–soil systems due to their symbiotic associa- tions with most land plants to form arbuscular mycorrhizae. It is well known that AMF can influence plant fitness, community structure, biodiversity and ecosystem variability [31,17]. Mycor- rhizal plants have greater ability to absorb mineral nutrients and soil water leading to increased plant fitness which may ultimately lead to better survival under stressed environmental conditions [15,14,7]. It has been suggested that the success of any ecosystem restoration efforts is likely to depend on establishment of mycor- rhizae and thus AMF should receive special attention [16]. In a natural ecosystem, several AMF species coexist in the same root system where competitive ability of the isolate becomes an important consideration. While, there are studies which show that the occurrence and abundance of a vascular species in a particular community may depend on the presence of one to several specific AMF [1,32], other studies provide strong evidence that plant species influence the composition of AMF communities [12]. Plant species exert an important selective force on AMF populations, either directly through their internal root environment or indirectly through their influence on the soil [13]. Most mycorrhizal research on the responses of individual plants to AMF colonization involved plants inoculated by single AMF species. Whether, these isolates that are highly successful colonists individually are more compet- itive in mixed populations is unknown. In a number of studies, plant growth response to natural soil inoculum has been compared to that on sterile soil. However, experimental evidence highlighting differential plant species-related growth patterns in soils that are likely to support dissimilar AMF communities are lacking, as bulk of the studies have been carried out with a limited number of easily cultured AMF which are often poorly represented in the natural root-colonizing AMF communities [24]. The role of mycorrhiza in natural plant population and multispecies communities remains poorly understood. Curculigo orchioides Gaertn. is a rhizomatous perennial plant native of tropical and subtropical climates. The rhizomes of the plant are reported to display anticancerous properties [23]. It is enlisted in the ‘‘vulnerable’’ category of IUCN red list of plants and is threatened by habitat loss, poor seed set and germination, high * Corresponding author. Tel.: þ91 011 9818497035; fax: þ91 011 27667830. E-mail address: rupamkapoor@gmail.com (R. Kapoor). Contents lists available at ScienceDirect European Journal of Soil Biology journal homepage: http://www.elsevier.com/locate/ejsobi 1164-5563/$ – see front matter Ó 2009 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.ejsobi.2009.04.005 European Journal of Soil Biology 45 (2009) 328–333