Search

Quinoa (Chenopodium quinoa Willd.) produces bitter-tasting triterpene saponins that must be removed prior to consumption, significantly adding to production costs. Breeders have therefore prioritized the development of low-saponin “sweet” cultivars with little concern for the ecological benefits these compounds may confer. Quinoa saponins are thought to provide protection against herbivores and microbial pathogens, although there is very little data to support these assumptions. Here we begin to address the question of whether biologically relevant concentrations of saponins exert negative effects against insects and pathogens that attack quinoa, as well as against species not associated with quinoa. Using bran of the coastal genotype Cáhuil as the source of saponins, we conducted feeding assays with larvae of 3 noctuid insect species. Antifungal activity against 8 species was assayed using bran extract incorporated into PDA media. Quinoa bran showed insecticidal activity against only the non-quinoa feeder Pseudaletia impuncta, while the quinoa feeders Trichoplusia ni and Feltia subterranea were not affected. The bran extract inhibited fungal colony growth of Alternaria arborescens, Botrytis cinerea, and Phytophthora cinnamomi by approximately 50% but had less growth inhibitory effect on Fusarium oxysporum f. sp. cepae, Pestalotiopsis clavispora, Penicillium digitatum, Geotrichum sp., and the quinoa pathogen Phoma sp. The relatively higher inhibitory activity against some pathogen species did not necessarily correlate with their expected pathogenicity against quinoa. The results of this study suggest that, while the quinoa saponins present in bran and bran extracts may provide some protection against certain insects and phytopathogens, species-specific responses need further exploration. Resumen La quínoa (Chenopodium quinoa Willd.) produce saponinas triterpénicas de sabor amargo que deben eliminarse antes del consumo, lo que aumenta significativamente los costos de producción. Por lo tanto, los fitomejoradores han priorizado el desarrollo de cultivares “dulces” bajos en saponina con poca consideración por los beneficios ecológicos que estos compuestos pueden conferir. Se cree que las saponinas de quínoa brindan protección contra herbívoros y fitopatógenos microbianos, aunque existen muy pocos datos que respalden estos supuestos. En este estudio comenzamos a abordar la pregunta de si concentraciones biológicamente relevantes de saponinas ejercen efectos negativos contra los insectos y patógenos que atacan a la quínoa, así como también contra especies no asociadas con la quínoa. Utilizando el salvado del genotipo costero Cáhuil como fuente de saponinas, realizamos ensayos de alimentación con larvas de 3 especies de insectos lepidópteros de la familia Noctuidae. La actividad antifúngica se ensayó contra 8 especies fitopatogénicas usando extracto de salvado incorporado en medios PDA. El salvado de quinua mostró actividad insecticida solo contra la especie de insecto que no afecta quínoa Pseudaletia impuncta, mientras que los insectos que son plaga de quínoa Trichoplusia ni y Feltia subterranea no se vieron afectados. El extracto de salvado inhibió el crecimiento de colonias de los fitopatógenos Alternaria arborescens, Botrytis cinerea y Phytophthora cinnamomi en aproximadamente un 50%, pero tuvo un menor efecto inhibidor del crecimiento sobre Fusarium oxysporum f. sp. cepae, Pestalotiopsis clavispora, Penicillium digitatum, Geotrichum sp. y el patógeno de la quínoa Phoma sp. La actividad inhibidora relativamente mayor contra algunas especies de patógenos no se correlaciona necesariamente con su patogenicidad esperada contra la quínoa. Los resultados de este estudio sugieren que, si bien las saponinas de quínoa presentes en el salvado y los extractos de salvado pueden proporcionar cierta protección contra ciertos insectos y fitopatógenos, las respuestas específicas de las especies necesitan una mayor exploración.

Quinoa (Chenopodium quinoa Willd.) produces bitter-tasting triterpene saponins that must be removed prior to consumption, significantly adding to production costs. Breeders have therefore prioritized the development of low-saponin “sweet” cultivars with little concern for the ecological benefits these compounds may confer. Quinoa saponins are thought to provide protection against herbivores and microbial pathogens, although there is very little data to support these assumptions. Here we begin to address the question of whether biologically relevant concentrations of saponins exert negative effects against insects and pathogens that attack quinoa, as well as against species not associated with quinoa. Using bran of the coastal genotype Cáhuil as the source of saponins, we conducted feeding assays with larvae of 3 noctuid insect species. Antifungal activity against 8 species was assayed using bran extract incorporated into PDA media. Quinoa bran showed insecticidal activity against only the non-quinoa feeder Pseudaletia impuncta, while the quinoa feeders Trichoplusia ni and Feltia subterranea were not affected. The bran extract inhibited fungal colony growth of Alternaria arborescens, Botrytis cinerea, and Phytophthora cinnamomi by approximately 50% but had less growth inhibitory effect on Fusarium oxysporum f. sp. cepae, Pestalotiopsis clavispora, Penicillium digitatum, Geotrichum sp., and the quinoa pathogen Phoma sp. The relatively higher inhibitory activity against some pathogen species did not necessarily correlate with their expected pathogenicity against quinoa. The results of this study suggest that, while the quinoa saponins present in bran and bran extracts may provide some protection against certain insects and phytopathogens, species-specific responses need further exploration.