Effect of endophytic Bacillus and arbuscular mycorrhiza fungi (AMF) against Fusarium wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici

Background Fusarium wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici (FOL) is a serious disease that causes significant economic losses in tomato production. Seventeen endophytic Bacillus isolates from tomato roots of Meghalaya were tested for antagonistic and plant growth promotion activities. Dominating arbuscular mycorrhiza fungi (AMF) spores were isolated from the rhizosphere soils of tomato grown in Meghalaya. The effect of different combinations of AMF and endophytic Bacillus on Fusarium wilt severity and growth of tomato plant under pot and field conditions was studied. Results The endophytic Bacillus isolates ERBS51 and ERBS10 showed a maximum inhibition against FOL, with 58.43 and 55.68%, respectively, in a dual culture experiment. ERBS51 and ERBS10 were identified as Bacillus velezensis and Bacillus sp., respectively, based on 16s rRNA sequencing. Both isolates were found positive for iturin A, surfactin, bacillomycin D, protease, cellulase, pectinase, alpha-amylase, siderophore, ammonia production and ZnCO3 solubilization. Funneliformis mosseae and Glomus fasciculatum were the dominating AMF species in tomato rhizosphere of Meghalaya. The result of pot and field experiments revealed that out of all the treatments, combination of Funneliformis mosseae + Glomus fasciculatum + Bacillus velezensis + Bacillus sp. was shown to be the best in reducing the severity of Fusarium wilt to 77.44 and 66.74%, respectively. F. mosseae + G. fasciculatum + B. velezensis + Bacillus sp. also recorded the highest in most growth attributes and yield. Conclusions Endophytic Bacillus (B. velezensis and Bacillus sp.) and AMF (F. mosseae and G. fasciculatum) were safe and effective biocontrol agents against Fusarium wilt of tomato.

REVISÃO: MICRORGANISMOS PROMOTORES DE CRESCIMENTO APLICADOS NA PRODUÇÃO DE MORANGOS

Introdução: Os microrganismos desempenham funções fundamentais no desenvolvimento vegetal. Eles atuam como catalizadores na obtenção de nutrientes indispensáveis para o seu crescimento e indutores de respostas contra patógenos e estresses abióticos. É de comum acordo que a sustentabilidade se tornou uma obrigatoriedade para o desenvolvimento e integralização da sociedade, principalmente na agricultura que é uma atividade indispensável e que pode acarretar danos severos ao meio ambiente quando praticada inconsequentemente. A cultura do morango é um exemplo, o estado de Minas Gerais lidera a produção nacional com 2,8 mil ha cultivados e que essencialmente necessitam de alternativas ecologicamente viáveis para sua manutenção. Objetivo: Sendo assim, o presente trabalho foi elaborado com o objetivo de revisar a literatura e proporcionar um breve estudo de caso sobre as pesquisas acerca de microrganismos promotores de crescimento aplicados à cultura do morango, apontando quais vem sendo estudados e como podem contribuir para o desenvolvimento e produção. Material e Métodos: Foram realizadas buscas em diversas plataformas de pesquisa, o critério adotado foi o termo “strawberry inoculation” como palavra chave assim recorrendo a trabalhos relevantes que contemplassem o caráter descritivo e científico da aplicação de inóculos bacterianos e fúngicos em cultivares de morango. Resultados: Os trabalhos revisados evidenciaram o benefício que os microrganismos acarretam na obtenção de nutrientes como P, K, Ca e Fe, seja com sua acumulação no solo ou nos tecidos foliares (Bacillus sp.e Aspergillus sp.), também possibilitando na redução da adubação nitrogenada e incremento do tamanho e matéria seca da raiz (Azospirillum brasiliense). Respostas na indução de tolerância a seca são promovidas (Glomus mosseae), como também o biocontrole do fungo necrotrófico Botrytis cinerea (várias espécies de Bacillus sp.). Melhoras na qualidade dos frutos também são proporcionados como aumento de compostos flavonóides e fenólicos (Glomus intraradices) e o aumento dos açúcares, antocianinas, modulação do pH, ácido málico e compostos voláteis (Pseudomonas sp.+ Funneliformis mosseae, Septoglomus viscosum, Rhizophagus irregulares. Conclusão: Visto o atual advento na produção de inoculantes de natureza biológica este estudo expõe diversos trabalhos que podem contribuir como inspiração tecno científica para a elaboração de novas pesquisas e produtos, além de contribuir na disseminação de conhecimentos sobre microbiologia e sustentabilidade agrícola.

Biochemical response and nutrient uptake of two arbuscular mycorrhiza-inoculated chamomile varieties under different osmotic stresses

Background Water-deficit stress is known as one of the most severe environmental stresses affecting the growth of plants through marked reduction of water uptake, which leads to osmotic stress by lowering water potential. Adopting appropriate varieties using soil microorganisms, such as arbuscular mycorrhiza (AM) fungi, can significantly reduce the adverse effects of water deficiency. This study aimed to evaluate the role of Funneliformis mosseae on nutrient uptake and certain physiological traits of two chamomile varieties, namely Bodgold (Bod) and Soroksári (Sor) under osmotic stress. For pot culture, a factorial experiment was performed in a completely randomized design with three factors: osmotic stress (PEG 6000) was applied along with Hoagland solution at three levels (0, -0.4 and -0.8 MPa), two German chamomile varieties (Bodgold (Bod) and Soroksari (Sor)), and AM inoculation (Funneliformis mosseae species (fungal and non-fungal)) at four replications in perlite substrate. Results Osmotic stress significantly reduced the uptake of macro-nutrients (N and P) and micro-nutrients (Fe, Cu, Mn, and Zn) in the shoots and roots. Moreover, the level of osmolytes (total soluble sugars and proline) and the activity of antioxidant enzymes in the shoots of both varieties increased under osmotic stress. Regarding the Sor variety, the level of these compounds was more satisfactory. AM improved plant nutrition uptake and osmolyte contents while enhancing antioxidant enzymes and reducing the adverse effects of osmotic stress. Under osmotic stress, the growth and total dry weight were improved upon AM inoculation. Conclusions In general, inoculation of chamomile with AM balanced the uptake of nutrients and increased the level of osmolytes and antioxidant enzymes; hence, it improved plant characteristics under osmotic stress in both varieties. However, it was found to be more effective in reducing stress damages in the Sor variety.

Comunidades de hongos formadores de micorrizas arbusculares en talares del partido de Magdalena, provincia de Buenos Aires: Interacción con la invasión de Ligustrum lucidum

Las invasiones biológicas representan una de las mayores amenazas para la integridad de los ecosistemas nativos a nivel global. La dispersión de plantas exóticas puede afectar no solo la estructura de las comunidades vegetales sino también a las funciones ecosistémicas y a la microbiota del suelo, incluyendo a los hongos micorrícicos arbusculares (HMA). Estos microorganismos, pertenecientes al phylum Glomeromycota, forman parte de una de las asociaciones simbióticas más importantes y ampliamente distribuidas de las plantas. Diversos estudios acerca de la expansión de plantas invasoras en diferentes ecosistemas han reportado que los HMA pueden tener un rol tanto en la facilitación como en la limitación de la expansión de especies no nativas. El objetivo de este trabajo de tesis consistió en describir y analizar el efecto del establecimiento de la especie exótica Ligustrum lucidum en bosques nativos de Celtis tala y Scutia buxifolia ubicados en la localidad de Magdalena sobre la estructura de las comunidades de HMA así como el rol que tienen estos microorganismos en el proceso de invasión. Los sitios de muestreo se ubicaron a lo largo de transectas con un gradiente de abundancia de la especie exótica. Sobre estas transectas se describió estructuralmente la comunidad arbórea, se analizaron las características edáficas y se tomaron muestras de suelo destinadas a la identificación de las morfoespecies Glomeromycota. Se caracterizó a las comunidades de HMA en los sitios de estudio a través de la determinación de esporas presentes en el suelo del bosque y de la realización de un ensayo con plantas trampa utilizando métodos de identificación basados en caracteres morfológicos. La abundancia de morfoespecies, familias y los parámetros de diversidad y riqueza de la comunidad fúngica a lo largo del gradiente estudiado fueron analizados para determinar posibles cambios provocados por el establecimiento de L. lucidum. Finalmente, se llevó a cabo un ensayo en invernáculo que permitió evaluar la colonización y respuesta a la micorrización en plántulas de C. tala y L. lucidum al ser inoculadas con suelo proveniente de los sitios de bosque nativo e invadido. Los resultados obtenidos indicaron que la invasión provoca cambios en la estructura de la comunidad arbórea que conducen gradualmente al desplazamiento de las especies nativas del talar. Se encontraron diferencias en la disponibilidad de materia orgánica, nitrógeno y fósforo en los sitios de muestreo, hallándose valores menores de concentración en los sitios invadidos. Se lograron identificar treinta y dos morfoespecies de Glomeromycota pertenecientes a nueve familias. Las morfoespecies más abundantes fueron Septoglomus constrictum, Sclerocystis sinuosa, Diversispora spurca y Entrophospora infrequens. Además, se cita por primera vez en Argentina a las morfoespecies Glomus hoi (Glomeraceae), Dentiscutata cerradensis (Gigasporaceae) y Corymbiglomus corymbiforme (Diversisporaceae). La familia más abundante fue Glomeraceae. La composición de la comunidad de HMA mostró diferencias entre las distintas situaciones de vegetación, la riqueza específica aumentó en los sitios con mayor presencia de la especie exótica mientras que la diversidad disminuyó. Si bien la mayor parte de las morfoespecies encontradas no mostró marcadas variaciones en su distribución asociadas a la vegetación, la abundancia de las morfoespecies Rhizophagus aggregatus, Paraglomus albidum, Acaulospora delicata, Acaulospora mellea, Diversispora spurca, Sclerocistys sinuosa, Entrophospora infrequens, Rhizoglomus microaggregatus, y Funneliformis mosseae se asoció positivamente con L. lucidum, mientras que la morfoespecie Scutellospora sp. 2 se asoció positivamente con la vegetación nativa, por lo que puede señalarse como la más susceptible a ser perjudicada por el establecimiento de la especie exótica. Las familias Claroideoglomeraceae, Glomeraceae, Entrophosporaceae y Acaulosporaceae se relacionaron positivamente con la especie invasora. Los resultados del ensayo de invernáculo permitieron comprobar la asociación de C. tala y L. lucidum con los HMA. Se determinó que la especie invasora tiene la capacidad de asociarse con los hongos presentes en el bosque nativo y que luego de su establecimiento los cambios provocados en la comunidad de hongos favorecen la simbiosis micorrícica en L. lucidum y perjudican la interacción de la especie nativa con estos hongos. Este proceso podría facilitar el establecimiento de L. lucidum en los talares y el desplazamiento de las especies nativas. Además, se evidenció que las relaciones de mutualismo entre los HMA y ambas especies vegetales estudiadas pueden ser influenciadas por la presencia de la otra al crecer en conjunto, y que este efecto es diferente para cada especie y de acuerdo con la comunidad de HMA presente en el suelo, indicando la existencia de mecanismos complejos de interacción. Este estudio constituye el primer reporte de interacción entre los HMA y L. lucidum en este ecosistema y uno de los primeros trabajos de investigación realizados acerca del rol de estos hongos en el establecimiento de esta especie invasora de gran impacto a nivel mundial.

Arbuscular Mycorrhizal Colonization Increased Above-Belowground Feedback of Maize In a Degraded Coal Mining Area Soil By Increasing The Photosynthetic Carbon Assimilation And Allocation of Mazie

A three-compartment culture system was used to study the mechanism by which the AM fungus Funneliformis mosseae influences host plant growth and soil organic carbon (SOC) content in a coal mining area. A 13CO2 pulse tracing technique traced the allocation of maize photosynthetic C in shoots, roots, AM fungus and soil to detect C accumulation and allocation in mycorrhizal (inoculated with Funneliformis mosseae) and non-mycorrhizal treatments.AM fungal inoculation significantly increased the 13C concentration and content in both above- and below-ground plant parts. Mycorrhizal inoculation significantly enhanced the anti-aging ability by increasing soluble sugars and catalase activity (CAT) in maize leaves while reducing foliar malondialdehyde content (MDA) and leaf temperature to promote plant growth. AM fungi also increased P uptake to promote maize growth. Soil organic carbon (SOC), glomalin, microbial biomass carbon (MBC) and nitrogen (MBN) contents increased significantly after inoculation. A mutually beneficial system was established involving maize, the AM fungus and the microbiome, and the AM fungus became an important regulator of C flux between the above- and below-ground parts of the system. Inoculation with the AM fungus promoted plant growth, C fixation and allocation belowground to enhance soil quality. The positive above-belowground feedback appeared to be established.

Beneficial Effects of the Five Isolates of Funneliformis mosseae on the Tomato Plants Were Not Related to Their Evolutionary Distances of SSU rDNA or PT1 Sequences in the Nutrition Solution Production

The symbiosis and beneficial effects of arbuscular mycorrhizal fungi (AM fungi) on plants have been widely reported; however, the effects might be unascertained in tomato industry production with coconut coir due to the nutrition solution supply, or alternatively with isolate-specific. Five isolates of AM fungi were collected from soils of differing geographical origins, identified as Funneliformis mosseae and evidenced closing evolutionary distances with the covering of the small subunit (SSU) rDNA regions and Pi transporter gene (PT1) sequences. The effects of these isolates on the colonization rates, plant growth, yield, and nutrition uptake were analyzed in tomato nutrition solution production with growing seasons of spring–summer and autumn–winter. Our result indicated that with isolate-specific effects, irrespective of geographical or the SSU rDNA and PT1 sequences evolution distance, two isolates (A2 and NYN1) had the most yield benefits for plants of both growing seasons, one (E2) had weaker effects and the remaining two (A2 and T6) had varied seasonal-specific effects. Inoculation with effective isolates induced significant increases of 29.0–38.0% (isolate X5, T6) and 34.6–36.5% (isolate NYN1, T6) in the plant tissues respective nitrogen and phosphorus content; the plant biomass increased by 18.4–25.4% (isolate T6, NYN1), and yields increased by 8.8–12.0% (isolate NYN1, A2) compared with uninoculated plants. The maximum root biomass increased by 28.3% (isolate T6) and 55.1% (isolate E2) in the autumn–winter and spring–summer growing seasons, respectively. This strong effect on root biomass was even more significant in an industry culture with a small volume of substrate per plant. Our results reveal the potential benefits of using selected effective isolates as a renewable resource that can overcome the suppressing effects of sufficient nutrient availability on colonization rates, while increasing the yields of industrially produced tomatoes in nutrition solution with coconut coir.

PROTEOMIC STUDIES IN THE SYMBIOTIC ASSOCIATIONS BETWEEN ARBUSCULAR MYCORRHIZAL FUNGI Funneliformis mosseae WITH MELON (Cucumis melo L.) UNDER SALT CONDITIONS

Arbuscular mycorrhizal fungi (AMF) that can cause mutualism with higher plants. Some studies showed that the symbiosis of AMF will increase nutrients absorption, the capacity of anti-stress (e.g. drought, salt and disease) by melon (Cucumis melo L.). This study evaluated the roles of proteins on salt-tolerance mechanism after melon was symbiotic with AMF (Funneliformis mosseae). The melons were cultivated in the hydroponic solution containing 0 M, 0.042 M or 0.084 M NaCl for inoculated AMF and non-AMF inoculated seedlings. Root apice of AMF seedling after treating with different NaCl concentrations that were chosen for the estimation of proteins. The results showed that 12 proteins were significantly different after treating with different sodium chlorite (NaCl) concentrations, with proteins that four upregulated and eight downregulated. The tolerance of NaCl stress by root of melon that was inoculated by AMF were attributable to cellular activities involved in carbohydrate metabolism, energy metabolism, production of organic acid, relief of salt injury, which may be critical for promotion of nutrients absorption, anti-stress. This study can offer an important clue to advanced genomic exploration for the inoculation of AMF on different plants.