Self- and cross-incompatibility in Asparagus officinalis and Asparagus densiflorus cv. Sprengeri

Abstract

Garden asparagus, Asparagus officinalis L. (off), is dioecious and reproductively isolated from a related ornamental, monoecious Asparagus densiflorus (Kunth) Jessop cv. Sprengeri (spr). Since the latter is a potentially valuable source of germplasm, a study was initiated to identify hybridization barriers. Intra-and inter-specific crosses were made using 32 plants of two commercial cultivars of off and 17 plants of three introductions of spr. Part of the pollinated pistils were fixed and examined via fluorescence microscopy. In some combinations of genotypes, incompatibility reactions were detected: (i) off x off: in the stigmatic tissue, (ii) spr x spr: on the stigmatic surface and in the style, and (iii) spr x off: on the stigmatic surface, in the stigmatic tissue, and in the style. Although pollen tubes reached the ovules in most combinations of genotypes, seeds were only produced in intraspecific crosses. It is concluded that two types of internal barriers are acting: cross-incompatibility at the pollen-stigma and pollen-style levels, and stronger post-stylar barriers that had not been determined yet. RCsumC: L'asperge de jardin, Asparagus ofSicinalis L. (off), est dioi'que et reproductivernent isolee d'une espkce ornementale voisine, 1'Asparagus densiflorus (Kunth) Jessop cv. Sprengeri (spr), une esptce monoi'que. Comrne cette dernitre pourait constituer une source interessante de gerrnplasme, les auteurs ont amor@ une etude pour identifier les barrikres i l'hybridation. 11s ont effectuC des croisements intra-et inter-specifiques en utilisant 32 plantes appartenant i deux cultivars commerciaux de off et 17 plants de trois introductions de spr. Une partie des pistils pollinises ont Ctt fixes et examines par rnicroscopie en fluorescence. Dans certaines combinaisons de gtnotypes, ils ont observe des reactions d'incornpatibilitC : (i) off x off: dans les tissus des stigmates, (ii) spr x spr : sur la surface des stigmates et dans le style, et (iii) spr x off: sur la surface des stigmates, dans les tissus des stigmates, et dans le style.Bien que des tubes polliniques atteignent les ovules dans la plupart des combinaisons de genotypes, les graines ne sont produites que dans les croisements intra-sptcifiques. Les auteurs concluent que les deux types de barrikres internes agissent : incornpatibilitt de croisement au niveaux pollen-stigmate et pollen-style, et qu'il y a des barritres post-stylaires plus fortes que ce qui avait t t C determine jusqu'ici.

Substitutes for genome differentiation in tuber-bearing Solanum: interspecific pollen-pistil incompatibility, nuclear-cytoplasmic male sterility, and endosperm

“…Camadro and Peloquin (1981) proposed a genetic model with dominant CI genes in styles that prevent fertilization by pollen carrying specific dominant complementary genes. This model, which assumes segregation for both type of loci, accounts for the results of both UI and BI incompatibility in inter-and intraspecific crosses in tuber-bearing Solanum and also accommodates the results obtained in similar crosses in Asparagus between species that do not possess a selfincompatibility system (Marcellán and Camadro 1996). A few genes are similarly involved in cross-incompatibility reactions in maize.…”

Taxonomy of the western European endemic Asparagus prostratus (A. officinalis subsp. prostratus) (Asparagaceae)

“…These results suggest that even in the absence of any other internal barriers (e.g. cross-incompatibility, see Marcellan & Camadro, 1996) gene-flow from diploid A. officinalis into tetraploid A. prostratus via the direct production of tetraploid zygotes (which, if they survived to produce plants, might then be able to interbreed with normal tetraploid A. prostratus) is likely to be very severely restricted by a very low frequency of successful tetraploid zygote formation. It should be remembered that as commercial asparagus growers try to eliminate females from cropping fields because of their lower yield of shoots, transfer of male A. officinalis pollen to female A. prostratus is likely to be overwhelmingly the most frequent in situations where cross-pollination between a commercial asparagus crop and a wild stand of A. prostratus may occur.…”

Cross-incompatibility and self-incompatibility: unrelated phenomena in wild and cultivated potatoes?

“…However, there are many exceptions, such as the finding of compatibility in SI x SC crosses (see Eijlander et al 2000), and incompatibility in other SC -SI combinations (Hermsen and Ramanna 1976;Camadro and Peloquin 1981;de Nettancourt 2001;Hayes et al 2005;Baek et al 2015). The "SI x SC" rule fails to explain bilateral CI; moreover, CI has been reported in allogamous species without a GSI S-locus system such as maize Evans 2005, 2010) and carrot (Ibañez and Camadro 2015), and in a dioecious species, garden asparagus (Marcellán and Camadro 1996).…”