Pollen morphology and viability in Bromeliaceae

Abstract

Pollen morphology characterization is important in taxonomy, conservation and plant breeding, and pollen viability studies can support breeding programs. This study investigated pollen morphology and male fertility in 18 species of Bromeliaceae with ornamental potential. For morphological characterization, pollen grains were acetolyzed and characterization of exine was done using scanning and transmission electron microscopy. Pollen viability was investigated by in vitro germination and histochemical tests. Species belonging to Aechmea and Ananas genera presented medium size pollen, except for Ae. fasciata, with large pollen. Al. nahoumii, P. sagenarius and the Vriesea species analyzed showed large pollen, except for V. carinata, with very large pollen. Pollen of Aechmea, Ananas and P. sagenarius presented bilateral symmetry, diporate, exine varying from tectate to semitectate. Al. nahoumii and Vriesea species presented pollen with bilateral symmetry, monocolpate; exine was semitectate, reticulate and heterobrochate. Germination percentage and tube growth were greater in SM and BKM media. Histochemical tests showed pollen viability above 70% for all species, except for Ananas sp. (40%). Pollen morphology is important for the identification of species, especially in this family, which contains a large number of species. High rates of viability favor fertilization and seed production, essential for efficient hybrid production and conservation.

Bromeliads going batty: pollinator partitioning among sympatric chiropterophilous Bromeliaceae

“…For each drop, we counted the pollen grains using the ‘scan’ technique (Caballero-Martínez et al 2009) and thus determined the frequency of bromeliad pollen. The bromeliad pollen could be easily distinguished from the pollen of other families present in the samples, but it is difficult with some genera at subfamily level (Silva et al 2016; Souza et al 2017). In this case, the only overlapping species from the same genus were both species of Werauhia , and no bat was captured at that moment.…”

Pollen morphology and viability of Tillandsia (Bromeliaceae) species by light microscopy and scanning electron microscopy

“…Investigations of pollen morphology are important to support taxonomic (Khan et al, 2019; Majeed et al, 2020; Nazish et al, 2019) and conservation studies and to choose species for controlled crosses in genetic improvement programs aimed to obtain promising hybrids (Silva, Ribeiro, Luizi‐Ponzo, & Faria, 2016; Souza, Souza, et al, 2017). Recent research has shown that micromorphological traits observed by light microscopy (LM) and scanning electron microscopy (SEM) provide more detailed knowledge of the morphology of pollen grains, contributing to the identification, classification and delineation of the species belonging to different families, such as Caryophyllaceae (Cui, Hu, Ren, & Liu, 2020; Ullah, Zafar, et al, 2018; Ullah, Zaman, et al, 2018), Lamiaceae (Gul et al, 2019), and Melanthiaceae (Hu, Zhao, Zhao, & Liu, 2020).…”

“…Many studies have been published describing the pollen morphology and ultrastructure of Bromeliaceae species, such as Ehler and Schill (1973), Erdtman and Praglowski (1974), Roubik and Moreno (1991), Wanderley and Melhem (1991), Halbritter (1992), Halbritter and Till (1998), Tardivo and Rodrigues (1998), Vervaeke, Parton, Deroose, and De Proft (2003), Souza, Mendonça, and Gonçalves‐Esteves (2004), Moreira, Cruz‐Barros, and Wanderley (2005), Soares, Souza, Rossi, and Souza (2011), Silva et al (2016), Souza, Souza, et al (2017), Santos, Versieux, Wanderley, and Luz (2018), Schroeder, Junior, Dec, and Mouga (2019), and Santos, Wanderley, Versieux, and Luz (2020). However, due to the size of the family, these studies are insufficient.…”

“…Besides pollen morphology, it is important to understand the pollen viability for conservation these species (Souza, Souza, et al, 2017). Pollen grains can be conserved by cryopreservation, among other methods, to assure maintenance of a genetic pool of each species and to support selection of species for controlled crosses, especially in cases of asynchronous flowering (Souza, Souza, et al, 2017; Souza, Versieux, et al, 2017; Souza, Souza, Rossi, Ledo, & Martinelli, 2015).…”

Genome composition and pollen viability of Jatropha (Euphorbiaceae) interspecific hybrids by Genomic In Situ Hybridization (GISH)

“…Other difficulties may be related to problems in the meiotic and post-meiotic behavior of these hybrids, which can generate plants of little or no agronomic value, with low fertility or sterility due to reduction in the production of viable pollens and seeds. Thus, the evaluation of pollen viability is essential for the success of interspecific crosses (Pagliarini, 2000;Souza et al, 2017), including Jatropha species. In addition, Genomic In Situ Hybridization (GISH) studies of interspecific hybrids can provide relevant information for breeding programs, allowing differentiation of the parental genomes in hybrid cells and the detection of non-homologous recombination, which is fundamental for the introgression of new traits into material derived from interspecific hybrids.…”