Effects of two dark septate endophytes inoculation on growth promotion in tomato (Solanum lycopersicum L.) plants

ALMIRÓN, C. C; CASET, M. L; PONSO, M; ARECO, VANESA; CHIOCCHIO, VIVIANA; YARYURA, PABLO M

Congreso; XVIII Congreso de la Sociedad Argentina de Microbiología General; 2023

Plant-microbe interactions are widely studied ecosystem relationships, as its symbiosiswith arbuscular mycorrhizal fungi, has long been considered the only mutualistic fungal-plant association. However, in the last decade there has been an increase in the number offungi capable of forming this type of association with plants, including a group known asdark septate endophytes (DSE). DSE belongs to the Phylum Ascomycota, and constitutesone of the least studied groups of fungi worldwide with great potential for use as plant growthpromoters. The objectives of this work were: [a] Identify and characterize two DSE isolatesfrom tomato roots (C23) and Rhodes grass (GR1A), and [b] Evaluate the plant growthpromotion of these fungi on tomato crops. For these purposes, the taxonomic identificationof isolates was confirmed using a molecular technique by amplification of the ITS4-ITS5sequence and BLAST analysis. In vitro plant growth-promoting features of DSEs asamylase, cellulase and phosphate solubilization, indole-acetic acid, and siderophoreproduction were analyzed. To evaluate plant growth promotion, tomato seeds (Hybrid:ICHIBAN) were inoculated with each DSE on germination trays with substrate GrowMixMultiPro, 7 plants per treatment were grown in 1 L pots for 60 days in a greenhouse and anuninoculated control treatment was included. The growth variables evaluated were: thenumber of leaves, plant height, stem diameter, dry weight (DW) of leaves, stems and root,and root length. In addition, photosynthetic pigment content was determined and rootstructure was evaluated using saRIA software. Data were analyzed by analysis of variance(P≤0.05) with LSD Fisher as a posteriori test. Isolate C23, identified as Alternaria alternata,showed in vitro cellulase activity, amylase, indole-acetic acid production, and siderophores.While GR1A, identified as Setosphaeria rostrata, showed in vitro phosphate solubilizationand only amylase activity. Inoculation of both DSE (individual or combined) generatedstatistically significant increases in plant height, stem DW, and leaf carotenoid content, withrespect to the control. The combined inoculation also significantly modified the leaf areaand root structure of the plants, generating increases in root area, total root length, andlateral root production, with respect to the control. The results suggest that these DSEisolates, inoculated alone or combined on tomato seeds, could be used for the developmentof biotechnological products to be applied as biofertilizers in this crop.