Subdioecy in Consolea spinosissima (Cactaceae): breeding system and embryological studies

Abstract

The breeding system and the embryology of Consolea spinosissima, a tree-like opuntioid endemic to Jamaica, were investigated. Morphological and embryological studies revealed that the species is subdioecious, with three sexual morphs present in the 150 × 120 m plot studied at Hellshire Hills, Jamaica. The female morph has pistillate flowers with open stigma lobes, no pollen grains, and sets fruit. The male morph has cryptic staminate flowers with closed stigma lobes, viable pollen grains, and a nonfunctional gynoecium that does not set seed. The weak hermaphrodite morph has low fruit set and "perfect" flowers that superficially resemble the functionally staminate flowers of the male morph. These perfect flowers reach anthesis with viable pollen grains, with no or only a few functional ovules, and with the style supporting pollen tube growth. Embryological studies showed that the critical stage for sex determination occurs earlier in pistillate than in staminate and perfect flowers. Anthers of pistillate flowers abort prior to microspore tetrad formation, whereas ovules of the staminate and perfect flowers degenerate after the complete maturation of the embryo sac. Based on flower structure and embryological data, we hypothesize that the ancestor of C. spinosissima is/was hermaphroditic.

Comparative microsporangium development in male‐fertile and male‐sterile flowers ofConsolea(Cactaceae): When and how does pollen abortion occur

“…Pistacia vera L. staminate flower; Hormaza & Polito, 1996). On the other hand, developmental inhibition would leave behind a more or less atrophied organ such as shriveled anthers with no pollen grains (Chaudhury et al 1994;Strittmatter et al 2002), anthers with non-functional pollen grains (Anderson & Symon, 1989;Caporali et al 2003), or indehiscent anthers (Arabidopsis msH mutant; Dawson et al 1992). According to Wu and Cheung (2000), programmed cell death (PCD) may be involved in either or both pathways.…”

“…In this paper we focus on male sterility and its role in sex determination in a cryptically dioecious/subdioecious breeding system. The Caribbean endemic Consolea (Opuntioideae, Cactaceae) has nine species (Areces-Mallea, 2001), the six accessible species were studied and found to be subdioecious/cryptically dioecious (C. spinosissima - Strittmatter et al 2002;C. corallicola -Negrón-Ortiz & Strittmatter, 2004; all the other speciesunpubl.…”

“…Lem using light and transmission electron (TEM) microscopy. Very few studies have investigated anther wall development and microsporogenesis in the Cactaceae (Neumann, 1935;Tiagi, 1954;Tiagi, 1961;Strittmatter et al 2002;Negró n-Ortiz & Strittmatter, 2004) and none have done so from an ultrastructural perspective. Thus this study is, to our knowledge, the first one to describe anther wall development and microsporogenesis in the Cactaceae using transmission electron microscopy (TEM).…”

Trioecy in Coccoloba cereifera Schwacke (Polygonaceae), a narrow endemic and threatened tropical species

“…Flowers with non-functional organs of the opposite sex have been recorded both in trioecious and subdioecious species (Fleming et al, 1994;Strittmatter et al, 2002). Strittmatter et al (2002) reported that the non-functional anthers in pistillate flowers could have been maintained because they are adaptive, i.e., they mimic the appearance of the anthers of the male and hermaphrodite types, aiding in pollinator attraction. It is possible that the resemblance of the different flower types of C. cereifera could also represent a case of self-mimicry.…”

Inception of maleness: auxin contribution to flower masculinization in the dioecious cactus Opuntia stenopetala

“…In the Cactaceae family, to date, there are 26 reported species, distributed among three of the four subfamilies, which develop unisexual flowers (Table S1). Most of these show non-functional vestiges of the opposite sex at anthesis (Lindsay and Dawson 1952;Bravo-Hollis 1978;Kimnach 1982;Leuenberger 1986;Del Castillo and González 1988;Hoffman 1992;Fleming et al 1994;ValienteBanuet et al 1997;Strittmatter et al 2002). The study of the mechanisms involved in unisexuality in Cactaceae species is an attractive model system because early evolutionary stages of the unisexuality process can be observed, probably due to the relatively recent origin of this family (Hershkovitz and Zimmer 1997;Nyffeler 2002;Edwards et al 2005).…”