Inception of maleness: auxin contribution to flower masculinization in the dioecious cactus Opuntia stenopetala.
In Opuntia stenopetala, flowers initiate as hermaphrodite; however, at maturity, only the stamens in male flowers and the gynoecium in female flowers become functional. At early developmental stages, growth and morphogenesis of the gynoecium in male flowers cease, forming a short style lacking stigmatic tissue at maturity. Here, an analysis of the masculinization process of this species and its relationship with auxin metabolism during gynoecium morphogenesis is presented. Histological analysis and scanning electron microscopy were performed; auxin levels were immunoanalyzed and exogenous auxin was applied to developing gynoecia. Male flower style-tissue patterning revealed morphological defects in the vascular bundles, stylar canal, and transmitting tissue. These features are similar to those observed in Arabidopsis thaliana mutant plants affected in auxin transport, metabolism, or signaling. Notably, when comparing auxin levels between male and female gynoecia from O. stenopetala at an early developmental stage, we found that they were particularly low in the male gynoecium. Consequently, exogenous auxin application on male gynoecia partially restored the defects of gynoecium development. We therefore hypothesize that, the arrest in male flower gynoecia patterning could be related to altered auxin homeostasis; alternatively, the addition of auxin could compensate for the lack of another unknown factor affecting male flower gynoecium development.
Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Av. Universidad 3000. Col. Universidad Nacional Autónoma de México, 04510, Mexico, D.F., Mexico.
Gregorio
G
Orozco-Arroyo
Sonia
S
Vázquez-Santana
Aldebaran
A
Camacho
Joseph G
JG
Dubrovsky
Felipe
F
Cruz-García
D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism; D035264:Flowers / Q000254:growth & development* / Q000648:ultrastructure; D057850:Hermaphroditic Organisms / Q000166:cytology / Q000254:growth & development; D007210:Indoleacetic Acids / Q000378:metabolism*; D009024:Morphogenesis / Q000502:physiology*; D029747:Opuntia / Q000254:growth & development* / Q000378:metabolism*; D012727:Sex Characteristics; D019849:Sex Determination Processes
D007210:Indoleacetic Acids