title: Effect of fungi and light on seed germination of three Opuntia species from semiarid lands of central Mexico.
abstract: Fungal attack under light reduces mechanical resistance of the testa of Opuntia seeds, making it easier for the embryo to emerge. However, the effect of fungi on Opuntia seed germination in darkness is unknown. We evaluated the combined effects of light and inoculation with Phoma medicaginis, Trichoderma harzianum, Trichoderma koningii, and Penicillium chrysogenum on germination of O. streptacantha, O. leucotricha, and O. robusta seeds, from central Mexico. We also evaluated the combined effects of seed age (2-, 3-, and 12-year-old seeds) and presence of fungi on the testa on O. streptacantha germination. All fungal species eroded the funicular envelope and promoted seed germination for O. leucotricha and O. streptacantha, but did more so in light than in darkness. For the latter species, younger seeds inoculated with fungi had lower germination than older ones. For O. robusta, we found that seeds inoculated with P. medicaginis and T. harzianum had similar germination in light and in darkness. Our results strongly indicate that deterioration of the testa by fungi is higher in light than in darkness.
authors.affiliation: Facultad de Agronomía, Universidad Autónoma de San Luis Potosí, Carretera San Luis Potosí, Matehuala Km. 14.5, Soledad de Graciano Sánchez, S.L.P., Mexico. pablo.delgado@uaslp.mx
authors.forename: Pablo
authors.initials: P
authors.lastname: Delgado-Sánchez
authors.forename: Juan Francisco
authors.initials: JF
authors.lastname: Jiménez-Bremont
authors.forename: María de la Luz
authors.initials: Mde L
authors.lastname: Guerrero-González
authors.forename: Joel
authors.initials: J
authors.lastname: Flores
mesh_terms: D001203:Ascomycota / Q000502:physiology* / Q000648:ultrastructure; D003624:Darkness; D018525:Germination; D025301:Hyphae; D008027:Light; D008800:Mexico; D008855:Microscopy, Electron, Scanning; D029747:Opuntia / Q000382:microbiology* / Q000502:physiology / Q000528:radiation effects / Q000648:ultrastructure; D010408:Penicillium chrysogenum / Q000502:physiology* / Q000648:ultrastructure; D012639:Seeds / Q000382:microbiology* / Q000502:physiology / Q000528:radiation effects / Q000648:ultrastructure; D014242:Trichoderma / Q000502:physiology* / Q000648:ultrastructure