Arbuscular mycorrhizal fungi (AMF) are ecologically important members of the soil microbial community. The AMF status of
Curcuma aromatica and
C. longa growing in different soil types (Shimajiri–Maji, Jagaru and Kunigami–Maji), on the main island of Okinawa, Japan, was assessed by investigating AMF colonization rate, AMF spore density, and relative abundance of AMF by fatty acid analysis in September 2010 and November 2011. AMF were also identified by SSU rRNA gene sequencing from roots in 2011. AMF colonization ranged from 4.1-63.9% in 2010 and 1.3-51.9% in 2011.
Curcuma plants cultivated in Kunigami–Maji showed a significantly lower AMF colonization rate, compared with other soils in 2011. The AMF spore density in soil was higher in Shimajiri–Maji and Jagaru, compared with Kunigami–Maji in 2011. Stepwise linear regression model with soil properties such as pH, EC, soil N concentration (mineral N or nitrate N) and available P concentration (Truog-P) for AMF status suggested that available P negatively, pH positively correlated to the AMF colonization rate or AMF spore density in both years. In total, 9 AMF phylotypes were identified by sequencing. The phylogenetic analysis showed that most of the identified AMF belonged to the genus
Glomus group A. A few clones representing phylotypes belonging to Acaulosporaceae, Diversisporaceae and
Glomus B group were amplified from some roots. These results could be important for the understanding of indigenous mycorrhizal symbiosis and the management of soil ecosystems in
Curcuma plants on the main island of Okinawa.
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