Poster #10

Differences in mycorrhizal inoculum potential of populations of endemic and introduced tomatoes at the Galapagos Islands
Jéssica Duchicela1, Ivan Astudillo- Estevez2,3, Pieter van ’t Hof2,3,4,

The Galapagos Islands constitute a highly diverse ecosystem and a unique source of variation in the form of endemic species. There are two endemic tomato species, Solanum galapagense and S. cheesmaniae, which can be found in harsh niches and survive under difficult environmental circumstances, and two introduced tomato species, S. pimpinellifolium and S. lycopersicum. Although S. galapagense has been granted the ‘least concern’ status by the IUCN, recent observations raised concerns about the decline of the endemic tomato populations in different habitats on various islands. These endemic tomatoes are confronted with an uncertain future because of the rapid proliferation of introduced and invasive species. As wild plants depend on their microbiomes to tolerate many biotic and abiotic stresses, we believe there is a need to characterize the biologically important microorganisms surrounding the Galapagos tomatoes. One of the most globally widespread symbionts is arbuscular mycorrhizal fungi (AMF), it arises from ancient symbioses and influences plant establishment and colonization. There is a lack of information regarding the mycorrhizal association with these plants at the Galapagos Islands. We performed mycorrhizal inoculum potential (MIP) test and mycorrhizal root colonization of plant rhizosphere from 59 samples of the four species collected at Isabela, Floreana, Cristóbal, and Santa Cruz islands. MIP from the two introduced species was higher than the two endemic species. MIP of rhizosphere soil with agricultural management history was higher than remanent soils in all islands. Relatively low numbers of AMF spores were present in the rhizosphere soil, and many appeared degenerate, although a range of genera was determined by morphotype, including Glomus, Diversispora, Septoglomus, Funneliformis, and Acaulospora. There were no differences between the genera diversity. Our findings suggest that the Solanum introduced species are more actively associated with mycorrhiza than endemic ones.

1Departamento de Ciencias de la Vida, Universidad de las Fuerzas Armadas ESPE, Sangolquí, Ecuador.2Colegio de Ciencias Biológicas y Ambientales, Universidad San Francisco de Quito (USFQ), Quito, Ecuador3Galápagos Science Center, Universidad San Francisco de Quito (USFQ), San Cristóbal, Galápagos, Ecuador4Instituto de Microbiología, Colegio de Ciencias Biológicas y Ambientales, Universidad San Francisco de Quito (USFQ), Quito, Ecuador

Corresponding authors Jessica Duchicela; e-mail: jiduchicela@espe.edu.ec,    Pieter van ’t Hof; e-mail: pvanthof@usfq.edu.ec