Inbreeding depression in garden and glasshouse chrysanthemums: germination and survivorship

Abstract

Sixty-six chrysanthemum (Dendranthema grandiflora) inbred selections, noninbred cultivars and hybrids, and D. makinoi were the base populations from which up to three generations of inbreds were obtained using multiple plant descent. Each parent possessed pseudo-self compatibility (PSC), which allowed seed set following self pollination. Rapid-generation cycling (laboratory seed ripening to heart stage and subsequent embryo rescue) reduced generation time and minimized confounding maternal with zygotic inbreeding depression during post heart-stage seed development. Selection criteria were male/female fertility and PSC. Two stages of the life cycle were chosen to evaluate inbreeding depression: germination (seed development to germination) and survivorship (fertile individuals at anthesis). PSC was environmentally interactive and genotype dependent, causing variable levels of self seed set between and within populations and generations.By the end of the second generation, families from all noninbred cultivars, D. makinoi, and one F1 hybrid were eliminated from the experiment due to self incompatibility and/or inbreeding depression. Postgermination inbreeding depression was severe in several advanced inbreds. Inbred progeny of most F1 or F2 hybrids expressed less or equal amounts of inbreeding depression compared to advanced inbreds. Linear regression coefficients for either germination or survivorship on percent homozygosity were negative. Correlation coefficients between percent germination and survivorship (as a percent of seed set) were highly significant for Minnesota inbreds (r = 0.67, P ~ 0.002) and hybrids (r = 0.67, P -< 0.006). The correlation coefficient was higher when percent germination and survivorship (as a percent of germinated seedlings) were compared (r = 0.95, P-< 0.001).

Asymbiotic germination of ornamental Vanda: in vitro germination and development of three hybrids

“…However, since S014 seeds germinated rapidly and developed to advanced stages, it is unclear whether S005 and S013 have low seed vigor possibly due to inbreeding. Breeding practices such as selfing, sib mating, and backcrossing, which are employed to search out recessive flower traits, may result in poor seedling germination and growth due to inbreeding depression (Anderson et al 1992;Pico et al 2007;Wang et al 1999). This may also contribute to the long duration to flowering of certain Vanda.…”

Inheritance of pseudo-self compatibility in self-incompatible garden and greenhouse chrysanthemums, Dendranthema grandiflora Tzvelv

“…While full-sib mating is a slower means of achieving homozygosity than selfing, it has been a useful means of circumventing SI when parents have 0% PSC. Additionally, it could be superior to selfing since sib-mating is a mild form of recombinant inbreeding (Anderson et al, 1992) and permits the breeder to select for strong SI and high outcross seed set simultaneously, thereby producing strongly SI parents for F1 hybrid seed production. These full-sibs were created by the breeding scheme developed by Stephens et al (1984) and crossed as follows: SIx mid PSC (84-161-28 x 17), SI x lowPSC (83-76-33 x 24), low PSC × SI (85-312-3 x 6), low PSC x low PSC (85-92-61 × 51; 85-341-4 × 9), and high PSC × low PSC (83-263-1 x 6).…”

“…When inbred population size was small, due to increased expression of SI in the respective parent or the cumulative expression of inbreeding depression, the values were pooled Table 1. Self and outcross seed set values (Anderson et al, 1992) pooled across environments and flowering periods, percent pseudo-self compatibility (%PSC) of chrysanthemum parents used to create base populations for PSC inheritance studies. The number of seeds generated from selfing were the initial size of the base population for each inbred family among families and Chi-square tests for heterogeneity were performed.…”

Chrysanthemum ×grandiflorum MN Sel’n. 90-275-27 Groundcover Garden Chrysanthemum

“…1). Anderson and Ascher (2000) noted that Fisher's coefficient of inbreeding (F) was an incomplete disomic or hexasomic mathematical equation to encapsulate all of the allohexaploid genetic factors (Anderson et al, 1992a(Anderson et al, , 1992b and inbreeding was thus expressed as ''I'' to represent the number of selfed, and/or half-or full-sib generations. On both sides of the pedigree, two thirdgeneration selfed inbreds (I = 3,0), MN Sel'ns.…”