Histological Study of Post-pollination Events in Spathodea campanulata Beauv. (Bignoniaceae), a Species with Late-acting Self-incompatibility

Abstract

The reproductive biology of Spathodea campanulata was investigated by means of hand-pollination experiments, observations of pollen tube growth using fluorescence microscopy, and serial sections of ovules in selfed and crossed pistils. Only cross-pollinated flowers developed fruits, and all selfed flowers abscised within 3-4 d. However, self pollen tubes grew successfully to the ovary, penetrating and fertilizing the majority of ovules by 48 h, indicating that S. campanulata is a species with late-acting self-incompatibility. The incidences of ovule penetration, fertilization and endosperm initiation were all significantly slower in selfed vs. crossed pistils, although no other signs of malfunctioning were detected. The possible role of such slow self pollen tube effectiveness as a recognition event is discussed within the context of the slow but not entirely suppressed self pollen tube growth reported for some species with conventional homomorphic self-incompatibility.

Self-sterility in the hexaploid Handroanthus serratifolius (Bignoniaceae), the national flower of Brazil

“…However, in the Handroanthus serratifolius individuals evaluated here, the fact that two fruits from hand self-pollinations with unviable seeds persisted up to the maturation of fruits from hand cross-pollinated pistils can be an indicative of inbreeding depression, which can mimic LSI (Seavey & Bawa 1986, Bittencourt et al 2003. In species with LSI, the simultaneous abortion of pistils from self-pollination treatment is expected (Bittencourt et al 2003).…”

“…The self-pollen tube growth and the ovule penetration observed in self-pollinated pistils, together with the increase in ovary size in self-pollinated pistils that will be aborted, indicate the occurrence of LSI (Gibbs & Bianchi 1993;Bittencourt et al 2003;Bittencourt & Semir 2005;Gandolphi & Bittencourt 2010). However, in the Handroanthus serratifolius individuals evaluated here, the fact that two fruits from hand self-pollinations with unviable seeds persisted up to the maturation of fruits from hand cross-pollinated pistils can be an indicative of inbreeding depression, which can mimic LSI (Seavey & Bawa 1986, Bittencourt et al 2003.…”

“…Eighty percent of the studied species present self-sterility, which is often characterized as a result of late-acting self-incompatibility (LSI) mechanisms (Gibbs & Bianchi 1993;Bittencourt et al 2003;Bittencourt & Semir 2005;Gandolphi & Bittencourt 2010). To date, all neopolyploid Bignoniaceae species have been found to be self-compatible (Gobatto-Rodrigues & Stort 1992;Bittencourt & Semir 2005;Bittencourt & Moraes 2010;Firetti-Leggieri et al 2013;Sampaio et al 2013a), although not all self-compatible species are neopolyploids (Dutra & Machado 2001;Yanagizawa & Maimoni-Rodella 2007;Qu et al 2007).…”

“…The LSI found in most species of Bignoniaceae allows pollen tube growth, ovule penetration, fertilization and endosperm development prior to self-pollinated pistil abscission (Bittencourt et al 2003;Bittencourt & Semir 2005;Gandolphi & Bittencourt 2010). In apomictic species, adventitious embryos develop irrespective of pollination but are able to reach maturity only when the endosperm is available (Bittencourt & Moraes 2010;Sampaio et al 2013b).…”

Sistema reprodutivo e polinização de Senna multijuga (Fabaceae) em Mata Atlântica Montana

“…Apesar disso, nem todos os registros de LSI em Fabaceae tem diferenciado os mecanismos de rejeição em pré-ou pós-zigótica. Evidências para a rejeição pós-zigótica podem ser observadas em várias espécies da família, assim como, em espécies de Bignoniaceae (Bittencourt et al 2003;Bittencourt & Semir 2005, 2006. Em Hymenaea stigonocarpa Mart.…”