Gibberellin reactivates and maintains ovary-wall cell division causing fruit set in parthenocarpic Citrus species

Publication date: Available online 27 February 2016 Source:Plant Science Author(s): Carlos Mesejo, Roberto Yuste, Carmina Reig, Amparo Martínez-Fuentes, Domingo J. Iglesias, Natalia Muñoz-Fambuena, Almudena Bermejo, Mª Antonietta Germanà, Eduardo Primo-Millo, Manuel Agustí Citrus is a wide genus in which most of the cultivated species and cultivars are natural parthenocarpic mutants or hybrids (i.e. orange, mandarin, tangerine, grapefruit). The autonomous increase in GA1 ovary concentration during anthesis was suggested as being the stimulus responsible for parthenocarpy in Citrus regardless of the species. To determine the exact GA-role in parthenocarpic fruit set, the following hypothesis was tested: GA triggers and maintains cell division in ovary walls causing fruit set. Obligate and facultative parthenocarpic Citrus species were used as a model system because obligate parthenocarpic Citrus sp (i.e. C. unshiu) have higher GA levels and better natural parthenocarpic fruit set compared to other facultative parthenocarpic Citrus (i.e. C. clementina). The autonomous activation of GA synthesis in C. unshiu ovary preceded cell division and CYCA1.1 up-regulation (a G2-stage cell cycle regulator) at anthesis setting a high proportion of fruits, whereas C. clementina lacked this GA-biosynthesis and CYCA1.1 up-regulation failing in fruit set. In situ hybridization experiments revealed a tissue-specific expression of GA20ox2 only in the dividing tissues...
Source: Plant Science - Category: Biology Source Type: research