Outcrossing and paternity in Glycine argyrea by paired fruit analysis

Abstract

Glyczne argyrea (Fabaceae), a perennial wild relative ofsoybean, has a dual flowering strategy of both self-fertilized cleistogamous flowers and chasmogamous flowers on the same plant. Using allozyme polymorphisms the frequency and pattern of outcrossing was determined. The genotypes of seeds from each of several fruit (legumes) per plant were analysed by starch gel electrophoresis, and the maternal genotype inferred. The maximum likelihood estimates of outcrossing rate for the chasmogamous flowers averaged 0.38. The observed level of heterozygosity in the adult population (H = 0.25) rompared with the level expected under random mating (h = 0.32) indicated that partial outcrossing was typical of this population. To analyse the mating pattern further, the pollen genotypes of several seeds per legume for pairs of legumes from the same plant were determined. About 35q, of fruit from chasmogamous flowers had no genetically detectable outcross progeny, presumably because they were not cross-pollinated effectively. The majority of the remaining fruit had seed which were of mixed origin (both self-fertilized and outcrossed), suggesting that insect pollination does not preclude self-fertilization. As might be expected from this entomophilous pollination system, the pollen of outcrossed seed within one fruit usually (85% of cross-pollinated legumes) came from one male source. Evidence of pollen carry-over was found in the other legumes. The joint distribution of male sources among the pairs of legumes (paired fruit analysis) showed that non-self sources were shared in 30% of pairs. The probability that two outcrossed seeds from the same fruit would be half-sibs was estimated as 0.15, and for two seeds from different fruit on the same plant as 0.42. There is a hierarchy of genetic identity within and among legumes on the same plant, and on different plants, providing scope for the operation of selection at different levels.

Mating system estimation via the one pollen parent model with the progeny array as the unit of observation

“…Several studies suggest that the model may be most useful in situations where the progeny in arrays derive from the single fruits. For example, Schoen (1985) and Brown, Grant, and Pullen (1986) found evidence in Ipomoea purpurea and Glycine argyrea, respectively, that seeds derived from outcrossing within the same fruit on a plant were more likely to share paternal parentage than seeds of different fruits on a plant. In the latter case, it was estimated that 85 per cent of the cross-pollinated seed within a fruit shared the same male parent.…”

Outcrossing rates and correlated mating within a population of Eichhornia paniculata (Pontederiaceae)

“…Partitioning progeny into those resulting from ambiguous mating events and those from detectable outcrossing allowed Schoen (1985) and Brown et a!. (1986) to compare correlations in selfed paternal parentage within and between fruits.…”

Fine-Scale Genetic Structure and Gene Dispersal in Centaurea corymbosa (Asteraceae). II. Correlated Paternity Within and Among Sibships

“…In this context, pure hardt 1987; Karron andMarshall 1990, 1993), or half-sib and pure full-sib families represent the extreme the success of mating events between nearby individuals alternatives of a continuum from uncorrelated to totally when inbreeding depression or self-incompatibility occorrelated mating events (e.g., polyads of mimosoid lecurs. Second, together with the outcrossing rate, the gumes and tropical figs; Nason et al 1998).…”

“…To what extent are correlated mating and correlated to limited mate availability. paternity accounted for by (a) limited pollen disDifferent methods have been developed to quantify persal, (b) the heterogeneity of flowering intensity correlated paternity using genetic markers (e.g., Schoen and flowering phenology among plants, and (c) the 1985; Brown et al 1986;Ritland 1988Dewoody self-incompatibility system? et al 2000).…”

“…portion within fruits than among fruits (Table 3), inducing a hierarchical pattern of correlated matings (e.g., When mating events were simulated accounting for limited pollen dispersal and the heterogeneity of pollen Schoen 1985; Brown et al 1986;Ritland 1989;Morgan and Barrett 1990;Muona et al 1991; Sampson production and phenology among plants, the level of correlated mating was still inferior to the one observed.…”