GIBBERELLIC ACID APPLICATION AND ITS INCIDENCE ON IN VITRO SOMATIC EMBRYOGENESIS AND FRUIT PARTHENOCARPY IN AN APOMICTIC CACTUS PEAR (OPUNTIA FICUS-INDICA (L.) MILL.) CLONE

Prickly pear cactus O. ficus-indica is known to express polyembryony at a range of 0,5-20%. This polyembryony is one of many forms of apomixis process by which some plant species are able to develop embryos without fertilization.
Such process has been described here in a local spineless accession of O. ficus-indica. Histological investigations realized on ovules picked 10 days after anthesis, revealed the presence of two separate kinds of apomixis, (i) a gametophytic one where embryos are developed in one or two embryo sacs via apomeiosis and (ii) a sporophytic (also called adventitious embryony) one where embryos are developed from unreduced cells of the nucellus.
Gametophytic embryogenesis reached advanced stages such as heart shaped embryos, but sporophytic embryogenesis remained at undifferentiated stages consisting in meristematic cells with large nuclei and dense cytoplasm.
Improvement of apomictic ability has been envisaged by GA₃ applications on emasculated flowers before anthesis, in order to enhance the in vitro somatic embryogenesis from immature embryos and also to produce parthenocarpic fruits.
These objectives have really been reached, indeed somatic embryogenesis from GA₃-treated explants developed more embryogenic callus than open-pollinated control and fruits obtained from emasculated and treated flowers showed a relative size reduction and contained empty seeds with persistent teguments.
Results were more evident in the case of 500 ppm GA₃ dose.

VIII International Congress on Cactus Pear and Cochineal

N. Kaaniche-Elloumi, E. Jedidi, K.B. Mahmoud, A. Chakroun, A. Jemmali

apomixis, gametophytic embryo, sporophytic embryo, GA₃, cactus pear

https://doi.org/10.17660/ActaHortic.2015.1067.31