Frontiers in Microbiology (Aug 2014)

Effect of crude plant extracts from some Oaxacan flora on two deleterious fungal phytopathogens and extract compatibility with a biofertilizer strain

  • Karla Isabel eLira-De León,
  • Karla Isabel eLira-De León,
  • Marco Vinicio Ramírez-Mares,
  • Vladimir eSánchez-López,
  • Mario eRamírez-Lepe,
  • Raúl eSalas-Coronado,
  • Norma F. eSantos-Sánchez,
  • Rogelio eValadez-Blanco,
  • Beatriz eHernandez-Carlos

DOI
https://doi.org/10.3389/fmicb.2014.00383
Journal volume & issue
Vol. 5

Abstract

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The antimicrobial activity of twelve plant extracts was tested against the phytopathogens Alternaria alternata and Fusarium solani. In addition, the compatibility of the extracts towards Bacillus liqueniformis, a biofertilizer and a non-target microorganism, was assessed. Plants tested belong to Euphorbiaceae, Asteraceae, Crassulaceae, Rubiaceae, Convolvulaceae, Verbenaceae, Orchidaceae, Nyctaginaceae, Boraginaceae, and Tiliaecae families and were collected in the State of Oaxaca. The antifungal activity of the plant extracts (50 to 100 mg/mL) against A. alternata and F. solani, was determined by measuring the mycelium radial growth and obtaining the minimum inhibitory concentration (MIC) of fungal growth. In addition, with the aim of finding plant extracts which are compatible with a B. licheniformis biofertilizer strain and to test the nontoxic nature of the treatments, the toxicity of the extracts towards this strain was evaluated using the agar diffusion method. Azoxystrobin (12 μg) and chloramphenicol (30 μg) were used as positive controls for the pathogens and for the non-target bacteria, respectively. Plant extracts inhibited fungal growth in the ranges of 0.76 to 56.17 % against F. solani and 2.02 to 69.07 % against A. alternata. The extracts of Acalypha subviscida, Ipomoea murucoides, Tournefortia densiflora and Lantana achyranthifolia showed MIC values between 5.77-12.5 mg/mL for at least one of the fungal species. The best treatment, Adenophyllum aurantium, exhibited a maximum inhibition for both F. solani (56.17%, MIC = 7.78 mg/mL) and A. alternata (68.64% MIC = 7.78 mg/mL), and resulted innocuous toward B. licheniformis. Therefore, this plant has an outstanding potential for the agroecological control of fungal phytopathogens in industrial crops.

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