Morphological and molecular diversity of arbuscular mycorrhizal fungi associated to Carica papaya L. rhizosphere in two agro-ecological zones in Cameroon

Abstract

The papaya tree is not very exploitable on the international market because of the post-harvest decline of the fruits. In this study, we identified arbuscular mycorrhizal fungi (AMF) from the rhizosphere of papaya in two agroecological zones of Cameroon (Njombe-Pendja: NP and Yaounde: Y). Morphological studies on the density, the rate of root colonization, the diversity of AMF species were evaluated. Molecular identification of AMF was performed by sequencing the small subunit (SSU) 18S rDNA gene region from soil samples. These genes were amplified from the AML and NS2 primers. The total number of spores per 100 g of dry soil was significantly different (P<0.05) depending on the sites, ranging from 391 in NP to 790 in Y sites. The frequency and intensity of root colonization was not significantly different in the two sites. Eleven (11) AMF belonging to seven (7) genera (Scutellospora, Gigaspora, Acaulospora, Entrophospora, Funneliformis, Glomus and Racocetra) were recorded. Two AMF species (T1: Scutellospora rosa and T6: Racocetra gregaria) were recorded at NP and absent at Y. The Shannon-Wiener index revealed a low diversity of AMF species. Homogeneity of species was recorded. Molecular analysis reveals that the AMF species obtained have sizes of 250 bp. Key words: Arbuscular mycorrhizal fungi, Carica papaya L., fungal, molecular and morphological identification, rhizosphere.