Trichoderma agriamazonicum sp. nov. (Hypocreaceae), a new ally in the control of phytopathogens.

The genus Trichoderma comprises more than 500 valid species and is commonly used in agriculture for the control of plant diseases. In the present study, a Trichoderma species isolated from Scleronema micranthum (Malvaceae) has been extensively characterized and the morphological and phylogenetic data support the proposition of a new fungal species herein named Trichoderma agriamazonicum. This species inhibited the mycelial growth of all the nine phytopathogens tested both by mycoparasitism and by the production of VOCs, with a highlight for the inhibition of Corynespora cassiicola and Colletotrichum spp. The VOCs produced by T. agriamazonicum were able to control Capsicum chinense fruit rot caused by Colletotrichum scovillei and no symptoms were observed after seven days of phytopathogen inoculation. GC-MS revealed the production of mainly 6-amyl-α-pyrone, 1-octen-3-ol and 3-octanone during interaction with C. scovillei in C. chinense fruit. The HLPC-MS/MS analysis allowed us to annotate trikoningin KBII, hypocrenone C, 5-hydroxy-de-O-methyllasiodiplodin and unprecedented 7-mer peptaibols and lipopeptaibols. Comparative genomic analysis of five related Trichoderma species reveals a high number of proteins shared only with T. koningiopsis, mainly the enzymes related to oxidative stress. Regarding the CAZyme composition, T. agriamazonicum is most closely related to T. atroviride. A high protein copy number related to lignin and chitin degradation is observed for all Trichoderma spp. analyzed, while the presence of licheninase GH12 was observed only in T. agriamazonicum. Genome mining analysis identified 33 biosynthetic gene clusters (BGCs) of which 27 are new or uncharacterized, and the main BGCs are related to the production of polyketides. These results demonstrate the potential of this newly described species for agriculture and biotechnology.

Enhanced mercury phytoremediation by Pseudomonodictys pantanalensis sp. nov. A73 and Westerdykella aquatica P71.

Mercury is a non-essential and toxic metal that induces toxicity in most organisms, but endophytic fungi can develop survival strategies to tolerate and respond to metal contaminants and other environmental stressors. The present study demonstrated the potential of mercury-resistant endophytic fungi in phytoremediation. We examined the functional traits involved in plant growth promotion, phytotoxicity mitigation, and mercury phytoremediation in seven fungi strains. The endophytic isolates synthesized the phytohormone indole-3-acetic acid, secreted siderophores, and solubilized phosphate in vitro. Inoculation of maize (Zea mays) plants with endophytes increased plant growth attributes by up to 76.25%. The endophytic fungi stimulated mercury uptake from the substrate and promoted its accumulation in plant tissues (t test, p < 0.05), preferentially in the roots, which thereby mitigated the impacts of metal phytotoxicity. Westerdykella aquatica P71 and the newly identified species Pseudomonodictys pantanalensis nov. A73 were the isolates that presented the best phytoremediation potential. Assembling and annotation of P. pantanalensis A73 and W. aquatica P71 genomes resulted in genome sizes of 45.7 and 31.8 Mb that encoded 17,774 and 11,240 protein-coding genes, respectively. Some clusters of genes detected were involved in the synthesis of secondary metabolites such as dimethylcoprogen (NRPS) and melanin (T1PKS), which are metal chelators with antioxidant activity; mercury resistance (merA and merR1); oxidative stress (PRX1 and TRX1); and plant growth promotion (trpS and iscU). Therefore, both fungi species are potential tools for the bioremediation of mercury-contaminated soils due to their ability to reduce phytotoxicity and assist phytoremediation.

Diversity of bacterial strains in biochar-enhanced Amazon soil and their potential for growth promotion and biological disease control in tomato

O uso de bactérias na promoção do crescimento e no controle biológico de doenças em plantas pode minimizar a contaminação ambiental causada pela aplicação indiscriminada de pesticidas e fertilizantes químicos. Objetivamos avaliar a promoção do crescimento e o controle biológico de Corynespora cassiicola em mudas de tomate mediadas por bactérias benéficas isoladas de solo amazônico não-rizosférico contendo diferentes dosagens de biocarvão, e identificar a quais grupos de bactérias os isolados pertencem. Obtivemos 200 isolados de parcelas experimentais contendo doses de biocarvão de 0, 40, 80 e 120 t ha-1. Destes, 53 foram selecionados por testes de colonização radicular. Com base nos parâmetros de promoção do crescimento, 25 isolados foram selecionados, identificados através de análise molecular e avaliados para produção de ácido indolacético (AIA), solubilização de fosfato e controle biológico. A melhor dose de biocarvão para a formação de colônias foi 40 t ha-1, e um modelo de regressão indicou 34 t ha-1como dose ótima. A produção de AIA foi observada em 18 (75%) isolados e dois (8%) isolados foram capazes de solubilizar fosfato. A eficiência na promoção do crescimento das raízes foi de até 125%, e a porcentagem de proteção das plantas variou de 50,3 a 59,0%. A caracterização molecular indicou que as bactérias utilizadas nesse estudo pertencem aos gêneros Bacillus e Lysinibacillus.(AU)