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Ann Bot. 2013 Aug;112(3):535-44. doi: 10.1093/aob/mct124. Epub 2013 Jun 11.

Gymnosperm B-sister genes may be involved in ovule/seed development and, in some species, in the growth of fleshy fruit-like structures.

Author information

1
Department of Biology, University of Padua, 35131 Padua, Italy.

Abstract

BACKGROUND AND AIMS:

The evolution of seeds together with the mechanisms related to their dispersal into the environment represented a turning point in the evolution of plants. Seeds are produced by gymnosperms and angiosperms but only the latter have an ovary to be transformed into a fruit. Yet some gymnosperms produce fleshy structures attractive to animals, thus behaving like fruits from a functional point of view. The aim of this work is to increase our knowledge of possible mechanisms common to the development of both gymnosperm and angiosperm fruits.

METHODS:

B-sister genes from two gymnosperms (Ginkgo biloba and Taxus baccata) were isolated and studied. The Ginkgo gene was also functionally characterized by ectopically expressing it in tobacco.

KEY RESULTS:

In Ginkgo the fleshy structure derives from the outer seed integument and the B-sister gene is involved in its growth. In Taxus the fleshy structure is formed de novo as an outgrowth of the ovule peduncle, and the B-sister gene is not involved in this growth. In transgenic tobacco the Ginkgo gene has a positive role in tissue growth and confirms its importance in ovule/seed development.

CONCLUSIONS:

This study suggests that B-sister genes have a main function in ovule/seed development and a subsidiary role in the formation of fleshy fruit-like structures when the latter have an ovular origin, as occurs in Ginkgo. Thus, the 'fruit function' of B-sister genes is quite old, already being present in Gymnosperms as ancient as Ginkgoales, and is also present in Angiosperms where a B-sister gene has been shown to be involved in the formation of the Arabidopsis fruit.

KEYWORDS:

B-sister gene; Ginkgo biloba; MADS-box genes; Taxus baccata; fruit growth; fruit-like structure

PMID:
23761686
PMCID:
PMC3718214
DOI:
10.1093/aob/mct124
[Indexed for MEDLINE]
Free PMC Article

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