ABSTRACT
NADPH oxidases are enzymes that have been reported to generate reactive oxygen species (ROS) in animals, plants and many multicellular fungi in response to environmental stresses. Six genes of the NADPH oxidase complex components, including vvnoxa, vvnoxb, vvnoxr, vvbema, vvrac1 and vvcdc24, were identified based on the complete genomic sequence of the edible fungus Volvariella volvacea. The number of vvnoxa, vvrac1, vvbema and vvcdc24 transcripts fluctuated with ageing, and the gene expression patterns of vvnoxa, vvrac1 and vvbema were significantly positively correlated. However, the expression of vvnoxb and vvnoxr showed no significant difference during ageing. In hyphae subjected to mechanical injury stress, both O2- and H2O2 concentrations were increased. The expression of vvnoxa, vvrac1, vvbema and vvcdc24 was substantially upregulated, but vvnoxb and vvnoxr showed no response to mechanical injury stress at the transcriptional level. Additionally, the transcription of vvnoxa, vvrac1, vvbema and vvcdc24 could be repressed when the intracellular ROS were eliminated by diphenyleneiodonium (DPI) chloride and reduced glutathione (GSH) treatments. These results indicated a positive feedback loop involving NADPH oxidase and intracellular ROS, which might be the reason for the oxidative burst during injury stress.
Subject(s)
Gene Expression Regulation, Fungal , Mycelium/genetics , NADPH Oxidases/genetics , Volvariella/enzymology , Volvariella/genetics , Fungal Proteins/genetics , Genome, Fungal , Glutathione/pharmacology , Mycelium/enzymology , Onium Compounds/pharmacology , Oxidation-Reduction , Reactive Oxygen Species/metabolism , Respiratory Burst , Stress, PhysiologicalABSTRACT
Volvariella bombycina es una especie de hongo saprófito comestible que crece en troncos de árboles muertos y sobre la cual existe abundante información acerca de su sabor y propiedades nutricionales y medicinales. En Guatemala esta especie se consume en diversas regiones templado-cálidas del país, pero a la fecha no existe ningún estudio sobre su cultivo a nivel local. La presente investigación se realizó con el fin de conocer el comportamiento de tres cepas guatemaltecas de V. bombycina cultivadas en desechos agroindustriales. Las cepas fueron aisladas de basidiomas recolectados en bosques cercanos a la Ciudad de Guatemala, utilizándose medio PDA para el aislamiento y temperatura de 30 ºC para incubación. En la producción de inóculo se calculó la tasa de extensión radial (RER) sobre granos de sorgo y trigo en cajas de Petri. Para la obtención de basidiomas se evaluaron seis sustratos de desechos agrícolas: pasto jaraguá, caña y olote de maíz, rastrojo de frijol, paja de trigo, paja de arroz y tronco de tonché (Ipomoea murucoides), en frascos de vidrio. Se encontró que no hubo diferencia estadística significativa en el análisis de la RER entre las cepas VNPNU-01 y AADM-01 (p > .05), pero sí con la cepa VNPNU-02 (p < .05). Se obtuvieron basidiomas de V. bombycina en los seis sustratos evaluados, siendo la cepa AADM-01 la más productiva. De acuerdo con este estudio, las tres cepas guatemaltecas de V. bombycina pueden ser utilizadas en la producción de basidiomas en desechos agrícolas, lo que permitiría obtener un alimento nutritivo y generar ingresos a quienes deseen cultivar este hongo.
Volvariella bombycina is a species of edible saprophyte fungus that grows on logs of dead trees and about which there is information about its taste and nutritional and medicinal properties. In Guatemala this species is consumed in several warm regions of the country, but there is still no study on its cultivation locally. The present investigation was carried out in order to know the behavior of three Guatemalan strains of V. bombycina when cultivated in agricultural wastes. The strains were isolated from basidiomata collected in forests close to Guatemala City, using PDA medium and a temperature of 30ºC for incubation. In the inoculum production, the radial extension rate (RER) was calculated using sorghum and wheat grains in Petri dishes. For obtaining basidiomata, six agricultural wastes substrates were analyzed: grazing grass, cane and corn cob, stubble of bean, wheat straw, rice straw and tonché trunk (Ipomoea murucoides), in glass jars. There was found no significant difference in the statistical analysis of the RER with the VNPNU-01 and AADM-01 strains (p > .05), but it was significant with the VNPNU-02 strain (p > .05). Basidiomata of V. bombycina were obtained in the six substrates evaluated, being the AADM-01 strain the most productive. According to this evaluation, the three Guatemalan strains of V. bombycina can be used in the production of basidiomas using agricultural wastes, what would allow the production of a nutritious food and generate another income for those who want to grow this mushroom.