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Compared to agrochemicals, bioinoculants based on plant microbiomes are a sustainable option for increasing crop yields and soil fertility. From the Mexican maize landrace "Raza cónico" (red and blue varieties), we identified yeasts and evaluated in vitro their ability to promote plant growth. Auxin production was detected from yeast isolates and confirmed using Arabidopsis thaliana plants. Inoculation tests were performed on maize, and morphological parameters were measured. Eighty-seven yeast strains were obtained (50 from blue corn and 37 from red corn). These were associated with three families of Ascomycota (Dothideaceae, Debaryomycetaceae, and Metschnikowiaceae) and five families of Basidiomycota (Sporidiobolaceae, Filobasidiaceae, Piskurozymaceae, Tremellaceae, and Rhynchogastremataceae), and, in turn, distributed in 10 genera (Clavispora, Rhodotorula, Papiliotrema, Candida, Suhomyces, Soliccocozyma, Saitozyma Holtermaniella, Naganishia, and Aeurobasidium). We identified strains that solubilized phosphate and produced siderophores, proteases, pectinases, and cellulases but did not produce amylases. Solicoccozyma sp. RY31, C. lusitaniae Y11, R. glutinis Y23, and Naganishia sp. Y52 produced auxins from L-Trp (11.9–52 µg/mL) and root exudates (1.3–22.5 µg/mL). Furthermore, they stimulated the root development of A. thaliana. Inoculation of auxin-producing yeasts caused a 1.5-fold increase in maize plant height, fresh weight, and root length compared to uninoculated controls. Overall, maize landraces harbor plant growth-promoting yeasts and have the potential for use as agricultural biofertilizers. [ABSTRACT FROM AUTHOR]

Maize hybrids have been developed to produce high yield, and combat diseases; however, their parental lines experience a decrease in vigor, genetic variability, and disease resistance, limiting their productive and adaptive potential. Considering that plant growth-promoting microorganisms can increase germination and vigor in maize seeds, the objective of this study was to evaluate the germination and vigor-promoting potential of Clavispora lusitaniae Y35 on the parental maize lines B-41 and B-50. The standard germination test was used, seeds were treated with a suspension of the microbial strain at a concentration of 1x108, and germination and seedling parameters were assessed. The inoculation of the microbial strain caused an increase in root length and seedling length of B-41, and in root number of the B-50 seedlings. The highest effect was observed in the seedlings of line B-41. This research indicates that C. lusitaniae Y35 has an effect on the germination of maize parental seeds and could be a candidate to promote germination of maize parental lines. [ABSTRACT FROM AUTHOR]

Maize is an important crop worldwide having vital nutritional, medicinal, and economic significance. It is vulnerable to a broad spectrum of emerging infections and diseases caused by Fusarium species which are collectively termed fusariosis. The negative consequences of fusariosis can stimulate a considerable economic loss in the food chain. With this context, this study evaluated the biological control potential of 127 fungal strains that were sampled from the rhizosphere of five different Mexican maize landraces. Results showed that the strain Trichoderma sp. CM-CNRG 444 was able to inihbit the growth of maize-pathogenic strains of Fusarium fujikuroi, F. incarnatum-equiseti, F. oxysporum, and F. sambucinum species complexes by colonisation and mycoparasitism on dual culture assays. The colonisation of Trichoderma sp. CM-CNRG 444 in seeds (42.5%), roots (67.5%), and crown tissue (75.5%) during maize germination reduces the tissues rot of Fusarium strains by 50%–100%. Additionally, plants co-inoculated with Trichoderma sp. CM-CNRG 444 and Fusarium strains were statistically similar to the control plants in the number of leaves, root system, stem length, and biomass accumulation. It is concluded that the fungal strain Trichoderma sp. CM-CNRG 444 protects maize seed germination, seedlings and plants development against fusariosis. Based on the findings, Trichoderma sp. CM-CNRG 444 can be used to develop an agent to control fusariosis in maize crop. [ABSTRACT FROM AUTHOR]