In vitro ectomycorrhiza formation by monokaryotic and dikaryotic isolates of Pisolithus microcarpus in Eucalyptus grandis

Abstract

-The formation of ectomycorrhizas by monokaryotic and dikaryotic isolates of Pisolithus microcarpus (Cooke & Massee) G. Cunn. in Eucalyptus grandis W. Hill ex Maid. was studied by in vitro synthesis in Petri dishes. The formation of ectomycorrhizas was observed for all strains tested. Ectomycorrhizas formed by the monokaryotic strains presented a sheath of hyphae around the roots and a Hartig net limited to the epidermis layer, typical of the angiosperm ectomycorrhizas. Colonization rates, a measure of the number of ectomycorrhizas in relation to the total number of lateral root tips, varied from 23 to 62%. Some monokaryotic strains stimulated the formation of lateral roots, promoting increases of up to 109% above the control. The presence of some of the isolates in the in vitro synthesis medium stimulated the production of thicker lateral root tips. The dimensions of the lateral roots tips and ectomycorrhizas varied from one isolate to the next, indicating a variation in their capacity to provoke morphological changes in the host plant roots. The dikaryotic strain M5M11 presented higher values for lateral root yield, number of ectomycorrhizas, and colonization percentage than the corresponding monokaryotic strains, M5 and M11. This indicated the possibility of selecting compatible performing monokaryotic isolates for the yield of superior dikaryotic strains. The set of monokaryotic strains tested varied greatly in their ability to colonize E. grandis roots and cause secondary metabolism-related morphological changes in roots, providing a wealth of model systems for the study of genetic, physiological, and morphogenetic processes involved in Pisolithus-Eucalyptus ectomycorrhiza formation.

Recent advances in population genetics of ectomycorrhizal mushroomsRussulaspp.

“…Regrettably, these studies did not give a clean determination of ploidy of emerging ectomycorrhizae. Theoretically, monokaryotic hyphae should be able to infect plant roots and form ectomycorrhizae, and several in vitro infection tests using monokaryotic strains have confirmed this prediction (Tranvan et al 2000; Costa et al 2010). Further investigations of spore germinations, infection experiments by monokaryotic hyphae, mycorrhizal synthesis experiment between monokaryotic and dikaryotic hyphae in nature should help us better understand the details of fungal life cycles.…”

In vitro EVALUATION OF EUCALYPTUS ECTOMYCORRHIZAE ON SUBSTRATE WITH PHOSPHORUS DOSES FOR FUNGAL PRE-SELECTION

“…The proportion of isolates able to form ectomycorrhizal colonies in E. urophylla related to the total studied isolates (54.5%) (Figure 4c) was lower than the one found in Picea glehnii (70%) (KASUYA et al, 1996) and the one observed in E. grandis (100%) (COSTA et al, 2010), which was also in vitro culture. These results demonstrate the importance of constant selection of EMF isolates for inoculation in commercial nurseries and point out in vitro synthesis assays to reduce cost in selection programs of ectomycorrhizal fungi.…”

Potencial de Aspergillus niger para biocontrole de patógenos fúngicos de solo

“…Esses microrganismos são divididos em duas classes principais: rizobactérias promotoras de crescimento vegetal (PGPR) e fungos promotores de crescimento vegetal (PGPF). Em ambos os casos, os microrganismos apresentam a capacidade de crescer em associação com a planta hospedeira, resultando em estímulo do crescimento vegetal (COSTA et al, 2010). Microrganismos promotores de crescimento colonizam a rizosfera, a superfície da raiz ou até mesmo os espaços intercelulares da epiderme e do córtex radicular, embora, na maioria das vezes, encontram-se principalmente aderidos à superfície da raiz (COSTA et al, 2010).…”