Embryo and aril development in yellow passionfruit (Passiflora edulis f. flavicarpa) and sweet passionfruit (Passiflora alata L.)

Author(s)

Sylvia Rodrigues da Silveira

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Centro de Energia Nuclear na Agricultura (CENA/STB)
• Defense date: 2014-09-30

Examining board members

Adriana Pinheiro Martinelli; Sandra Maria Carmello Guerreiro

• Advisor: Adriana Pinheiro Martinelli

Abstract

Passiflora is the largest genus in Passifloraceae and most of the commercially used species develop an aril around the seed, which is commercially important for fresh fruit consumption, and concentrate juice. Reproductive developmental studies associating morphoanatomical and molecular characteristics are essential for a better understanding of particularities of this genus. The present project aimed to characterize the development of Passiflora edulis Sims and Passiflora alata Curtis zygotic embryo and aril. Pollination of flowers were done manually, fruits and ovaries were collected at regular intervals after pollination and processed for scanning and light microscopy, for analysis of embryos and aril in different stages of development. Aril primordium is observed in pre-anthesis when the embryo sac is organized. Epidermic cells at the base of the funiculus undergo periclinal divisions forming a rim surrounding the raphe. Aril development is arrested until after fertilization when cell divisions are reactivated and the aril resume development into a multicellular structure surrounding the developing seed from the funicle towards the chalazal end. At approximately 14 days after pollination the aril already covers two thirds of the seed, and grows rapidly until the whole seed is covered. The endosperm is nuclear and starts developing soon after fertilization through successive divisions forming a syncytium mostly at the chalazal region, and around the developing embryo, replacing the nucellus. Cell walls are formed and the endosperm begins cellularization approximately 20 days after pollination. Embryogenesis initiates with the first division of the zygote, approximately 7 days after pollination. This first cell division is transversal and asymmetrical; the apical cell undergoes successive divisions leading to the subsequent stages of embryo development such as 4- and 8-celled, globular, heart-shaped, torpedo. Approximately 30 days after pollination, the embryo reaches the cotyledonary stage and thereafter grows only in size, consuming the endosperm and occupying its space in the seed. The first division of the zygote was observed around seven days after pollination (DAP), with the mature embryo formed approximately 30 DAP. Initial development of the aril primordium is observed at the ovule basal region, before anthesis/pollination. Embryo and aril development occurs simultaneously. These observations allowed for the definition of two specific stages of aril development for laser-capture-microdissection and further molecular analysis aiming at the evaluation of the molecular basis of aril differentiation in Passiflora. The morphoanatomical characterization of embryo and aril development in these species will serve as a source of information for the definition of specific developmental stages, which can be targets for molecular studies in Passiflora (AU)

• FAPESP's process: 11/16228-5 - Embryo and aril development in yellow passionfruit (Passiflora edulis f, flavicarpa) and sweet passionfruit (Passiflora alata L.)
• Grantee: Sylvia Rodrigues da Silveira
• Support Opportunities: Scholarships in Brazil - Master