Temperature regulating floral bud differentiation in loquat (Eriobotrya japonica Lindl.). Hormonal and genetic aspects.

• Autores: Ana Luisa García Lorca
• Directores de la Tesis: Carmina Reig Valor (dir. tes.), Vittorio Farina (dir. tes.)
• Lectura: En la Universitat Politècnica de València ( España ) en 2017
• Idioma: español
• Tribunal Calificador de la Tesis: Jorge Canhoto (presid.), Carlos Mesejo Conejos (secret.), Primo Proietti (voc.)
• Programa de doctorado: Programa de Doctorado en Recursos y Tecnologías Agrícolas por la Universitat Politècnica de València
• Materias:
  • Ciencias agrarias
    • Horticultura
      • Fruticultura
• Enlaces
  • Tesis en acceso abierto en: RiuNet
• Resumen

  • In loquat, apex of a current shoot changes from vegetative to reproductive stage during summer, i.e. under high temperature conditions. Indeed, just before floral bud differentiation, a decline in the growth rate due to high temperature takes place. The aim of this work is to study the role of this 'summer rest period' on the apex transition from vegetative to reproductive stage. For this purpose 1) sprouting of secondary shoots was promoted at different times, removing the main shoot, before, during and after floral bud differentiation occurred and 2) groups of trees were shifted to a greenhouse under average maximum temperature not exceeding 25 ° C during different periods from June to October.

    Floral bud differentiation was evaluated. LEAFY (LFY), APETALA (AP1), TERMINAL FLOWERING 1 (TFL1) and FLOWERING LOCUS T (FT1) expression and hormonal content in abscisic acid (ABA), gibberellins (GAs), indoleacetic acid (IAA) and cytokinins (CKs) were analyzed in bud collected during the summer.

    Results suggest that the date of shoot apex removal determining floral bud differentiation of new shoots, so that the percentage of the new reproductive shoots reduced with the delaying of apex removal. On the other hand, maximum average temperature not exceeding 25 ° C prevented floral bud differentiation. Buds of the trees under indoors conditons displayed lower expression of identity floral genes EjLFY and EjAP1 than buds of trees grown in field. On the contrary, the floral repressor EjTFL1 and EjFT1 gene expressed higher in buds of the trees grown indoors. Time-course of ABA decreased in buds of trees grown in field during studied period while in buds of trees under greenhouse conditions displayed a growing trend. Time-course of GAs, IAA and CKs concentrations did not show remarkable differences between buds of trees growing under field and indoors conditions. Accordingly, 1) secondary shoots emerged from mid- August are unfitness to flower and 2) maximum average tempertature 25±1 °C during the summer prevents floral bud differentiation, enhances ABA biosynthesis, reduces EjLFY and EjAP1 expression and enhance EjTFL1 expression in the apex.