Adriana Mayumi Yano-Melo

Tolerance of mycorrhized banana (Musa sp. cv. Pacovan) plantlets to saline stress

Abstract Arbuscular mycorrhizal fungi (AMF) are known to increase plant tolerance to abiotic stress, in particular soil salinity. Isolates of Acaulospora scrobiculata Trappe, Glomus clarum Nicolson & Schenck and Glomus etunicatum Becker & Gerdemann were investigated under glasshouse conditions. Inoculated banana plants (Musa sp. cv. Pacovan) showed higher nutrient contents and growth rates than the controls. G. clarum was particularly efficient as growth promoter, and improved the dry weight of root (80%), shoot (83%), and the total leaf area (60%) compared to non-inoculated plants. The salt tolerance of banana as measured by leaf number and plant height increased considerably in presence of Glomus isolates. Inoculation with specific AMF therefore constitutes an alternative method to reduce banana plant stress caused by soil salinization.

Checklist of the arbuscular mycorrhizal fungi (Glomeromycota) in the Brazilian semiarid

Seventy-nine species of arbuscular mycorrhizal fungi (AMF) are reported for the semiarid Caatinga biome of Northeast Brazil. Data are based primarily on research by L.C. Maia and co-workers during the past 20 years. The full checklist is available at www.mycotaxon.com/resources/weblists.html.

Fungos micorrízicos arbusculares e vermicomposto na aclimatação de Alpinia purpurata (Viell.) Schum e Zingiber spectabile Griff. (Zingiberaceae)

To select AMF and substrates that enhance production of micropropagated seedlings of Alpinia purpurata and Zingiber spectabile, tropical ornamental species, seedlings were inoculated with 1,500 infective propagules of Gigaspora albida, Glomus etunicatum and Acaulospora longula, in pots containing: (a) soil; (b) soil and vermicompost (3:1); (c) soil, sand and vermicompost (2:2:1). The experimental design was completely randomized in a factorial of: four inoculation treatments (three with AMF and uninoculated control), three substrates, with eight replicates for each plant species. After 70 (Z. spectabile) and 100 (A. purpurata) days of inoculation, plant growth parameters such as height, leaf and offshoots number, dry mass of shoots and roots, leaf area, as well as mycorrhizal colonization, AMF sporulation were evaluated. Significant interactions were not observed between AMF and substrates. In A. purpurata, the two substrates with vermicompost promoted growth, while in Z. spectabile only the substrate with higher proportion of this compound enhanced plant growth. Use of vermicompost reduced mycorrhizal colonization in both hosts and the sporulation of A. longula. During the acclimatization period, application of organic amendment is useful to induce formation of healthy seedlings of A. purpurata and Z. spectabile but it may be harmful to the AMF community.

Germination and germ tube growth of the arbuscular mycorrhizal fungi Gigaspora albida in different substrates

The role of the substrate on germination of Gigaspora albida Schenck & Smith was investigated. Spores were desinfested with 0.5% sodium hypochlorite (20 min.) and placed on Petri dishes over a Millipore filter, with one of the following media: a- 1% water-agar; b- water-agar + aqueous extract of roots of Panicum miliaceum L.; c- salt medium of Murashige & Skoog (MS) or sterilized sand; and incubated in the dark at room temperature (28oC ± 2). The experimental design was at random with four treatments and four replicates. Germination was evaluated every 7 days until the 28th day. The water-agar medium was the most feasible for spore germination at the 7th day, followed by the MS medium at the 14th day. Conversely, the sand and the root extract medium did not allow high germination. Spores maintained in water-agar also presented longer germ tubes than spores in the other treatments. Auxiliary cells were observed at the beginning of formation of hyphal branching in all treatments, however they were more numerous in the water-agar medium.

Responses of Guava Plants to Inoculation with Arbuscular Mycorrhizal Fungi in Soil Infested with Meloidogyne enterolobii

In the Northeast of Brazil, expansion of guava crops has been impaired by Meloidogyne enterolobii that causes root galls, leaf fall and plant death. Considering the fact that arbuscular mycorrhizal Fungi (AMF) improve plant growth giving protection against damages by plant pathogens, this work was carried out to select AMF efficient to increase production of guava seedlings and their tolerance to M. enterolobii. Seedlings of guava were inoculated with 200 spores of Gigaspora albida, Glomus etunicatum or Acaulospora longula and 55 days later with 4,000 eggs of M. enterolobii. The interactions between the AMF and M. enterolobii were assessed by measuring leaf number, aerial dry biomass, CO2 evolution and arbuscular and total mycorrhizal colonization. In general, plant growth was improved by the treatments with A. longula or with G. albida. The presence of the nematode decreased arbuscular colonization and increased general enzymatic activity. Higher dehydrogenase activity occurred with the A. longula treatment and CO2 evolution was higher in the control with the nematode. More spores and higher production of glomalin-related soil proteins were observed in the treatment with G. albida. The numbers of galls, egg masses and eggs were reduced in the presence of A. longula. Inoculation with this fungus benefitted plant growth and decreased nematode reproduction.

Fungos micorrízicos arbusculares e rizobactérias promotoras de crescimento na aclimatização de zingiber spectabile

Beneficial microorganisms are important for survival and development of micropropagated plants. The objective of this work was to evaluate the potential of arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR), isolated and/or combined (in dual inoculation) on acclimatization of Zingiber spectabile Griff. The experiment was carried out in a greenhouse using containers of 300 mL and dust from coconut shell (Amafibra®) as substrate. The experimental design was completely randomized with two AMF treatments [Glomus etunicatum (Ge) and the mixture of G. etunicatum and Gigaspora margarita (Ge/Gm)], two treatments with PGPR inoculation [Bacillus thuringiensis (HPF14) and B. pumilus (HPS6)], four treatments combining these microorganisms [Ge+HPS6, Ge+HPF14, Ge/Gm+HPS6 and Ge/Gm+HPF14] and a control treatment (not inoculated), with eight replicates. After 90 days survival percentage, height, leaf area, fresh and dry biomass of shoots (FBS and DBS) and roots (FBR and DBR), mycorrhizal colonization and content of macro and micronutrients in the shoot were evaluated. Co-inoculation (Ge/Gm+HPS6) benefited significantly the mycorrhization when compared to the other treatments, resulting in higher FBS than that produced by HPF14 inoculation. Although with 100% survival after the acclimatization period, the development of Z. spectabile inoculated with HPF14 isolated and/or combined with AMF is lower than the observed for control plants. The results suggest that the use of plant growth-promoting microorganisms should be done carefully, considering the cost/benefit of the application.

Application of Arbuscular Mycorrhizal Fungi during the Acclimatization of Alpinia purpurata to Induce Tolerance to Meloidogyne arenaria

An experiment was conducted to evaluate the tolerance of micropropagated and mycorrhized alpinia plants to the parasite Meloidogyne arenaria. The experimental design was completely randomized with a factorial arrangement of four inoculation treatments with arbuscular mycorrhizal fungi (AMF) (Gigaspora albida, Claroideoglomus etunicatum, Acaulospora longula, and a non-inoculated control) in the presence or absence of M. arenaria with five replicates. The following characteristics were evaluated after 270 days of mycorrhization and 170 days of M. arenaria inoculation: height, number of leaves and tillers, fresh mass of aerial and subterranean parts, dry mass of aerial parts, foliar area, nutritional content, mycorrhizal colonization, AMF sporulation, and the number of galls, egg masses, and eggs. The results indicated a significant interaction between the treatments for AMF spore density, total mycorrhizal colonization, and nutrient content (Zn, Na, and N), while the remaining parameters were influenced by either AMF or nematodes. Plants inoculated with A. longula or C. etunicatum exhibited greater growth than the control. Lower N content was observed in plants inoculated with AMF, while Zn and Na were found in larger quantities in plants inoculated with C. etunicatum. Fewer galls were observed on mycorrhized plants, and egg mass production and the number of eggs were lower in plants inoculated with G. albida. Plants inoculated with A. longula showed a higher percentage of total mycorrhizal colonization in the presence of the nematode. Therefore, the association of micropropagated alpinia plants and A. longula enhanced tolerance to parasitism by M. arenaria.

Associação Micorrízica em Plantas Forrageiras e seu Efeito no Crescimento de Duas Variedades de Cajanus cajan, Cultivados em Argissolo e Neossolo

Fungos micorrizicos arbusculares (FMA) e bacterias fixadoras de nitrogenio (BFN) formam associacoes mutualisticas com raizes de plantas, sendo ambos os simbiontes beneficiados. O microrganismo aumenta a absorcao de nutrientes do solo disponibilizando-o ao vegetal associado, que em troca fornece fotossintatos. Objetivou-se nesse trabalho avaliar a condicao micorrizica na rizosfera de duas variedades de Cajanus cajan e verificar se FMA e BFN podem beneficiar o crescimento dessa planta em dois tipos de solo. Amostras de solo foram coletadas avaliando-se a colonizacao micorrizica, o numero de glomerosporos e a ocorrencia de FMA. Para avaliar a eficiencia simbiotica foi realizado um experimento em DIC em fatorial, com quatro tratamentos (controle, FMA, FBN e FMA+FBN) x dois tipos de solo (argissolo-ARG e neossolo-NEO), em seis repeticoes. Foram avaliadas: area foliar, numero de folhas, biomassa fresca e seca da parte aerea e radicular e colonizacao micorrizica. No campo, houve diferenca significativa entre as variedades de feijao guandu na colonizacao micorrizica, com 65 e 40 %, respectivamente em Forrageiro e Petrolina. Essa diferenca pode estar relacionada a comunidade de FMA, sendo encontradas especies dos generos: Scutelospora, Acaulospora, Ambispora e Glomus. Ambas as variedades de C. cajan desenvolveram mais quando micorrizados em ARG, porem, essas diferencas nao sao observadas quando as plantas sao cultivadas em NEO. Assim, a eficiencia da simbiose e dependente do tipo de solo e do genotipo da planta. DOI:10.15528/2176-4158/rcpa.v12n1p31-34