Johny DE Jesus Mendonça

Brazil is one of the largest grain producers worldwide, with yields heavily dependent on ecologically and financially expensive inputs. One possible approach to reduce these inputs is inoculation with plant-growth-promoting bacteria, whose large-scale use depends on a continual search for new genotypes for inoculant production. Several bacteria with potential for this have been isolated from plants that are more adapted to stressful environments. Thus, we aimed to evaluate the potential of pangolão grass (Digitaria eriantha cv. Suvernola) endophytic bacteria both in vitro and on maize growth. To this end, endophytic bacteria were isolated from pangolão grass of a tropical semiarid climate and a random subset of 80 strains was evaluated for biological nitrogen fixation, HCN, IAA and siderophore production and calcium phosphate solubilization, and later for maize growth promotion. All strains were positive for at least one of these in vitro growth promotion mechanisms and some strains increased maize plant height and root length, including some with better results than plants receiving commercial inoculants, confirming the potential of endophytic bacteria from stress-adapted plants. In vitro results had poor correlation with plant growth promotion, which indicates that the common practice of using these laboratory techniques as a pre-selection tool before a subset of strains is evaluated for plant growth promotion might result in the rejection of potentially interesting strains.

Endophytic microorganisms such as arbuscular mycorrhizal fungi (AMF) and dark septate fungi (DSF) may influence plant development according to soil microbial interaction and fertility. The purpose of the work was to evaluate the effect of nitrogen levels on the interaction of AMF and DSF on initial sorghum growth. The experimental design was completely randomized in a 4 x 4 factorial scheme, corresponding to sorghum cultivation in four treatments (Control - without inoculation of AMF and three mycorrhizal isolates: UFLA351 - Rhizoglomus clarum, UFLA372 - Claroideoglomus etunicatum, and UFLA401 - Acaulospora morrowiae) and four nitrogen levels (N): 0, 100, 300, and 600 mg Kg-1 of N. The sorghum seeds presented the filamentous fungi Rhizoctonia, Colletotrichum, Curvularia, Fusarium, Helminthosporium and Mucor; and the bacterium Bacillus subtillis, which may have interfered with plant growth. In the UFLA351 and UFLA372 treatments, the increase in nitrogen levels reduces the initial growth of sorghum, but does not influence the colonization rate of endophytic fungi DSE. The UFLA401 isolate favors the initial growth of sorghum, but without nitrogen fertilization. The endophytic fungi “dark septate” can influence the rate of mycorrhizal colonization and, therefore, the initial growth of sorghum, depending on the microbial interaction. Os micro-organismos endofíticos, como os fungos micorrízicos arbusculares (FMAs) e os fungos “dark septate” (DSE), podem influenciar no desenvolvimento vegetal a depender da interação microbiana e da fertilidade do solo. Este trabalho teve como objetivo avaliar a interação de fungos micorrízicos arbusculares e da microbiota da semente no crescimento inicial do sorgo cultivado com níveis crescentes de nitrogênio, em estufa agrícola. O delineamento experimental utilizado foi o inteiramente casualizado em esquema fatorial de 4 x 4, correspondentes ao cultivo do sorgo em quatro tratamentos (Testemunha – sem inoculação fúngica e três isolados de fungos micorrízicos arbusculares: UFLA351 - Rhizoglomus clarum, UFLA372 - Claroideoglomus etunicatum e UFLA401 - Acaulospora morrowiae) com quatro níveis de nitrogênio (N): 0, 100, 300 e 600 mg.Kg-1 de N. O adubo nitrogenado utilizado foi ureia com 45% de N. As sementes do sorgo apresentaram os fungos filamentosos Rhizoctonia, Colletotrichum, Curvularia, Fusarium, Helminthosporium e Mucor; e a bactéria Bacillus subtillis, os quais podem ter interferido no crescimento das plantas. Nos tratamentos UFLA351 e UFLA372, o aumento dos níveis de nitrogênio reduz o crescimento inicial do sorgo, mas não influencia na taxa de colonização dos fungos endofíticos DSE. O isolado UFLA401 favorece o crescimento inicial do sorgo, mas sem adubação nitrogenada. Os fungos endofíticos “dark septate” podem influenciar na taxa de colonização micorrízica e, portanto, no crescimento inicial do sorgo, a depender da interação microbiana.

The search for sustainable agriculture has increased interest in using endophytic bacteria to reduce fertilizer use and increase stress resilience. Stress-adapted plants are a potential source of these bacteria. Some species of these plants have not yet been evaluated for this, such as pangolão grass, from which we considered endophytic bacteria as potential plant growth promoters. Bacteria from the root, colm, leaves, and rhizospheric soil were isolated, and 132 strains were evaluated for their in vitro biological nitrogen fixation, IAA and siderophores production, and phosphate solubilization. Each mechanism was also assessed under low N availability, water stress, and low-solubility Fe and P sources in maize greenhouse experiments. All strains synthesized IAA; 63 grew on N-free media, 114 synthesized siderophores, and 46 solubilized P, while 19 presented all four mechanisms. Overall, these strains had better performance than commercial inoculant in all experiments. Still, in vitro responses were not good predictors of in vivo effects, which indicates that the former should not be used for strain selection, since this could lead to not testing strains with good plant growth promotion potential. Their heterologous growth promotion in maize reinforces the potential of stress-adapted plant species as potential sources of strains for inoculants.

O tomateiro IPA06 é uma variedade que apresenta frutos resistentes ao transporte e adaptada ao cultivo rústico, cuja interação com fungos micorrízicos arbusculares (FMA) ainda não foi encontrada na literatura. O objetivo deste trabalho foi avaliar o crescimento e a colonização do tomateiro IPA06 cultivado com FMA em substrato orgânico. O delineamento experimental utilizado foi inteiramente casualizado composto pelo cultivo do tomateiro IPA06 em cinco tratamentos (controle – sem inóculo fúngico e quatro inoculantes de fungos micorrízicos: UFLA05 - Gigaspora albida, UFLA351 - Rhizoglomus clarum, UFLA372 - Claroideoglomus etunicatum e UFLA401 - Acaulospora morrowiae), em substrato orgânico, com 10 repetições. Os FMAs inoculados influenciam apenas no período de germinação das sementes do tomateiro. O emprego de substrato orgânico não inibe a colonização do tomateiro por FMAs. A colonização micorrízica do tomateiro IPA06 não garante incremento na biomassa vegetal, mas favorece a precocidade no florescimento, sendo responsivo aos isolados UFLA351 e UFLA401 que podem ser utilizados como inoculantes para cultivo orgânico

Arbuscular mycorrhizal fungi (AMF) and dark septate endophytic fungi (DSE) promote increase in plant biomass, depending on the soil and climate conditions and the interactions with the host plant. The objective of this study was to evaluate the interaction of exotic arbuscular mycorrhizal fungi and native DSE fungi on the initial growth of P. millegrana. A completely randomized experimental design comprising the Paspallum millegrana cutilvar with the following treatments: control - without AMF, and three exotic AMF isolates (UFLA351 - Rhizoglomus clarum, UFLA372 - Claroideoglomus etunicatum and UFLA401 - Acaulospora morrowiae), with four replications each. P. millegrana grass was colonized by exotic AMF by R. clarum (UFLA351, 11.9%), C. etunicatum (UFLA372, 39.6%), and A. morrowiae (UFLA401, 51.2%). P. millegrana was also colonized by native DSE fungi, but these did not interfere with the colonization by exotic AMF and plant development. P. millegrana is responsive to the inoculation of UFLAs isolates of exotic AMF, which may contribute to the grass growth and survival under field conditions. The process of surface disinfestation of seeds does not eliminate endophytic microorganisms, whose presence may influence plant colonization by AMF, as well as development of the host plant.

Paspalum millegrana grass is a member of the family Poaceae native to the Americas, whose interaction with native symbiotic fungi has not yet been reported. The objective of this study was to evaluate the interactions between the native microorganisms and arbuscular mycorrhizal fungi in the development of P. millegrana Schrad. The experimental design was completely randomized with seven treatments (control, without AMF; native microbial inoculant; native + UFLA05 Gigaspora albida; native + UFLA351 Rhizoglomus clarum; native + UFLA372 Claroideoglomus etunicatum; native + UFLA401 Acaulospora morrowiae, and a mix of all treatments). The substrate was autoclaved sand and coconut powder at 2:1, with eight repetitions. The variables analyzed were: mycorrhizal colonization, dark septate endophytic fungi colonization, number of mycorrhizal spores, dry shoot mass, dry root mass, root length and volume, number of tiller and mycorrhizal dependence. Mycorrhizal arbuscular fungi and dark septate endophytic fungi colonized P. millegrana. The sporulation of arbuscular mycorrhizal fungi associated with P. millegrana was influenced by mycorrhizal colonization, depending on the fungus-plant interaction. P. millegrana was responsive to native + UFLA05 and native + UFLA351. No correlation between tiller emergence and mycorrhizal colonization of P. millegrana was observed.

Na agricultura orgânica um dos principais problemas fitossanitários é a ocorrência de nematoides Meloidogyne spp., os quais podem reduzir em até 100% da produtividade a depender da interação com a planta hospedeira. O objetivo deste trabalho foi avaliar o efeito da interação de micro-organismos do solo, do substrato de cultivo do cogumelo comestível Lentinula edodes e do biofertilizante Protector® NM no controle de Meloidogyne incognita em quiabeiro cultivado em uma propriedade orgânica. O delineamento experimental utilizado foi inteiramente ao acaso composto por cinco tratamentos (controle - sem inoculação fúngica, sem fertilizante; Protector® NM – sem inoculação fúngica + fertilizante; dois isolados fúngicos de L. edodes (LED): LED-AJU1, LED-CHI e pela mistura de LED-CHI + Penicillium spp.) distribuídos em três blocos com 11 plantas por tratamento e por bloco. O controle do M. incognita pelo fungo L. edodes é influenciado pela colonização micorrízica, a depender da interação microbiana. A colonização do quiabeiro por fungos DSE não interfere no controle de M. incognita pelos isolados de L. edodes e o emprego do biofertilizante Protector® NM, mas influência na colonização por FMAs nativos a depender da interação. O biofertilizante Protector® NM e o isolado LED-CHI+Penicillium apresentam potencial no controle de M. incognita. A interação entre FMAs nativos e o isolado LED-CHI apresenta potencial no controle do nematoide M. incognita, o que representa uma alternativa para agricultura orgânica.

Os fungos micorrízicos arbusculares (FMA) são micro-organismos endofíticos capazes de promover o crescimento de plantas de interesse econômico a depender da interação microbiana com a planta, mas poucos são os trabalhos relacionados com a produção de inoculantes. O objetivo deste trabalho foi avaliar a produção de propágulos micorrízicos em cultivo sucessivo e/ou rotacionado em sorgo e em braquiária, sem o uso de estimuladores químicos. O delineamento experimental utilizado foi inteiramente ao acaso em parcelas subdivididas, cujas parcelas foram os tratamentos (três isolados de FMAs: UFLA351 - Rhizoglomus clarum, UFLA372 - Claroideoglomus etunicatum e UFLA401 - Acaulospora morrowiae) e as subparcelas os cultivos sucessivos em sorgo/braquiária e rotacional em braquiária, com quatro repetições. O cultivo sucessivo em sorgo ou em braquiária estimula a produção de esporos micorrízicos de R. clarum, C. etunicatum e A. morrowiae. A rotação de cultura sorgo-braquiária não garante incremento na esporulação, a depender do isolado micorrízico. A produção de vesículas e de arbúsculos depende da interação do fungo com a espécie de planta e não apenas da estação do ano. As vesículas podem aumentar a produção de esporos micorrízicos, a depender da interação FMA x planta e da época do ano.

Vetiver grass is a member of the grass family Poaceae. Its fast development is probably due to the interaction with native microbiota, whose influence has not been studied yet. The objective of this work was to evaluate the colonization and development of the vetiver grass (Chrysopogon zizanioides (L.) Roberty) inoculated with arbuscular mycorrhizal fungi and dark septate endophytic fungi. The experimental design was a completely randomized design with six treatments (control, without mycorrhizal fungi, native inoculants, UFLA05 - Gigaspora albida, UFLA351 - Rhizoglomus clarum, UFLA372 - Claroideoglomus etunicatum, and UFLA401 - Acaulospora morrowiae), with three replicates each. Vetiver grass tillers as well as the native microbial inoculum were obtained from the Lower São Francisco river experimental area, located in Sergipe state, Northeastern Brazil. There was a negative interaction between all tested UFLAs mycorrhizal isolates and the native microbiota (mycorrhizal and endophytic fungi) in the treatments, especially when taking into consideration plant height and volume of roots. The effects of inoculation with UFLA isolates may have been influenced by the presence of the native mycorrhizal fungi and the dark septate endophytic fungi. Vetiver grass was responsive to the native inoculant. The mycorrhizal colonization of the vetiver grass was vesicular, but the formation of the arbuscules can be influenced by the interaction between the fungus, plant, and the environment.