The site of self-incompatibility action in cupuassu (Theobroma grandiflorum)

• Published in: Revista brasileira de botânica Vol. 28; no. 3; pp. 569 - 578
• Main Authors: Ramos, Alessandra R., Venturieri, Giorgini A., Cuco, Silvia M., Castro, Neuza M.
• Format: Journal Article
• Language: English
• Published: Sociedade Botânica de São Paulo 01.09.2005
• Subjects: PLANT SCIENCES; ovule clearing; infertilidade; infertility; polinização controlada; clarificação de óvulos; controlled pollination
• ISSN: 0100-8404; 1806-9959
• DOI: 10.1590/S0100-84042005000300013

Cupuassu (Theobroma grandiflorum (Willd. ex Spreng.) Schumann) is a fruit tree that is attracting attention in Brazil and also in other tropical countries. Its pulp is used to prepare ice-cream, juices, jellies and many other home-made sweets. This species has a very low fecundity, attributed to problems with pollination and self-incompatibility, noted as being restrictive to the agronomic productivity of the species. Controlled pollinations between compatible and incompatible parents were made and flowers were collected at three times: 24, 48 and 72 h after pollinations, during the floral seasons of 1995 and 1998. In flowers collected 24 h after pollination, in both compatible and incompatible crosses, around 70% of ovules showed egg apparatus without evidences of sperm cell delivery; nevertheless some pollen tubes had been observed. Ovaries collected at 48 h showed different behaviors according to the type of cross. In the compatibles, 35% of ovules did not show evidences of gamete fusion. In incompatible crosses this number rose to 50%. Collected ovaries with 72 h, from compatible and incompatible crosses, showed respectively 1.2% and 14.2% of the ovules with the egg apparatus and polar nuclei only. In these ovaries, for the two types of crosses, the presence of sperm nuclei was common and the zygote was still undivided. The incompatibility action is occurring after fertilization, in a late self-incompatibility action.