Breeding systems inClivia(Amaryllidaceae): late-acting self-incompatibility and its functional consequences

Abstract

Late-acting (ovarian) self-incompatibility, characterized by minimal or zero seed production following self-pollen tube growth to the ovules, is expected to show phylogenetic clustering, but can otherwise be difficult to distinguish from early-acting inbreeding depression. In Amaryllidaceae, late-acting self-incompatibility has been proposed for Narcissus (Narcisseae) and Cyrtanthus (Cyrtantheae). Here, we investigate whether it occurs in the horticulturally important genus Clivia (Haemantheae) and test whether species in this genus experience ovule discounting in wild populations. Seed-set results following controlled hand pollinations revealed that Clivia miniata and C. gardenii are largely self-sterile. Self-and cross-pollinated flowers of both species had similar proportions of pollen tubes entering the ovary, and those of C. gardenii also did not differ in the proportions of pollen tubes that penetrated ovules, thus ruling out classical gametophytic self-incompatibility acting in the style, but not early inbreeding depression. Flowers that received equal mixtures of self-and cross-pollen set fewer seeds than those that received cross-pollen only, but it was unclear whether this effect was a result of ovule discounting or interactions on the stigma. The prevention of self-pollination by the emasculation of either single flowers or whole inflorescences in wild populations did not affect seed set, suggesting that ovule discounting is not a major natural limitation on seed production. Flowers typically produce one to three large fleshy seeds from approximately 16 available ovules, even when supplementally hand pollinated, suggesting that fecundity is mostly resource limited. The results of this study suggest that Clivia spp. are largely self-sterile as a result of either a late-acting self-incompatibility system or severe early inbreeding depression, but ovule discounting caused by self-pollination is not a major constraint on fecundity.

Spit it out: Monkeys disperse the unorthodox and toxic seeds of Clivia miniata (Amaryllidaceae)

“…12 months (Kiepiel & Johnson, 2014b). The mean (±SD) percentage of flowers that set fruit in a previous study was 25.30 ± 0.436 and each fruit contained 2.49 ± 1.609 seeds (Kiepiel & Johnson, 2014a). Typical interplant distances vary from 10 cm to 30 cm.…”

Self-incompatibility in Habranthus gracilifolius (Amaryllidaceae): pre- and post-pollination barriers

“…Within these conditions, there are species that are monomorphic, dimorphic in stigma height (with equal anthers heights in both morphs), distylous (two morphs with anthers and stigma in reciprocal heights), or tristylous (same as the last condition plus one intermediate morph) (Barrett et al 1996;Baker et al 2000). Amaryllidaceae members were also the focus of studies of pollinator shifts (Pérez-Barrales and Arroyo 2010; Kiepiel and Johnson 2014b), late-acting self-incompatibility (Vaughton et al 2010;Kiepiel and Johnson 2014a), and hybridization barriers (Marques et al 2007(Marques et al , 2016. Even though plenty Amaryllidaceae have been studied, most population reproductive systems remain unknown, particulary of the Southern Hemisphere, where most species are located (Kiepiel and Johnson 2014a).…”

Self-sterility May Be Due to Prezygotic Late-acting Self-incompatibility and Early-acting Inbreeding Depression in Chinese Chestnut

“…Variation in the size of normal selfed seeds and aborted seeds is usually regarded as one of the most important factors allowing the discrimination between EID and postzygotic LSI (Hao et al, 2012). It is assumed that LSI causes the uniform failure of self-fertilized ovules, whereas EID causes failure at various stages of development (Kiepiel and Johnson, 2014;Seavey and Bawa, 1986;Valtueña et al, 2010). There were no significant differences in normal seed characteristics following the SP and CP treatments (Table 6).…”