Abstract Detail

Developmental and Structural Section

Carmo-Oliveira, Renata [1], Araujo, Nayara [2].

Embryology, Polyembryony and Apomixis in Inga laurina (Sw.) Willd. (Fabaceae: Mimosoideae).

Inga species are tropical trees with small flowers and numerous stamens that attract a varied array of pollinators. These floral characteristics increase pollen flow and many species also have self-incompatibility systems. However, other Inga species are self-compatible and even apomitics. Inga laurina is a common tree in the Cerrado region, the Neotropical savanna areas of Central Brazil, which bears legume fruits with polyembryonic seeds. In some Cerrado species, polyembryony has been associated with polyploidy and apomixis, with consequences for their breeding biology and ecology. An interesting feature of I. laurina embryos is that they accumulate phenolic compounds, which render them darker in color and purportedly protect them from pathogens. The objectives here were to describe basic embryology of I. laurina, to determine its breeding system, describe the origin and development of the embryos, and quantify their phenolic compounds. The study was carried out at an urban area in Uberlândia, Minas Gerais, Brazil. Floral buds, flowers and fruits at different developmental stages were collected and fixed for histological analyses, and later also used for chemical analyses. We also compared genotipes of embryos and mother plants using DNA ISSR markers. In I. laurina, the microsporangium wall formation (endothecium, middle layer and tapetum) falls within the development of Dicotyledonous type. Four pollen mother cells were formed and yielded four sets of four pollen grains that remained together to form a polyad with 16 grains. The ovules are anatropous, bitegmic and the gametophyte develops into a Polygonum type embryo sac. Despite the apparently normal early embryology, our data showed that I. laurina is a pseudogamic and apomictic species. The adventitious embryos were of nucellar origin and developed more quickly, often suppressing the zygotic embryo, probably due to competition for nutrients. Molecular analyses confirmed this since all but one of the analyzed embryos were genetically identical to the mother plant. But the non-clonal embryo indicated that sexual embryos can develop and persist in mature seeds. The presence and amount of phenolic compounds varied among embryos and seem to be associated with the size of the embryo and not with its sexual or asexual origin. The occurrence of apomixis and adventitious embryony has been considered a strategy to improve eproductive success, establishment and occupation of Cerrado environments. In this sense, I. laurina is the first legume species in the region reported to present these features (CAPES, CNPq, FAPEMIG)

1 - Universidade Federal de Uberlandia, Instituto de Biologia, Uberlandia, MG, 38405-320, Brazil
2 - Universidade Federal de Uberlandia, Instituto de Biologia, Programa de Pós-graduação em Biologia Vegetal, Uberlandia, MG, 38405-320, Brazil

Keywords:
apomixis
inga
phenols
polyembryony.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PDS002
Abstract ID:333
Candidate for Awards:None