The red common bean (Phaseolus vulgaris L.) seedcoat colors produced by the dominant gene R and the dark red kidney gene rk d are very similar, making it difficult for breeders of red bean varieties to know which genotype is in their materials. A protocol employing test crosses with genetic stocks having known genotypes for seedcoat colors was developed to identify genotypes with either of two very similar dark red seedcoat colors: garnet brown controlled by rk d and oxblood controlled by R. Twenty bean varieties and breeding lines were test crossed with genetic tester stocks c u BC3 5-593 and b v BC3 5-593, and four of the varieties were test crossed with [? R] b v BC3 5-593. Analysis of the seedcoat colors and patterns in the F1 progenies from the test crosses demonstrated that unambiguous identification of the genotypes of the two dark red colors could be achieved using the c u BC3 5-593 and b v BC3 5-593 testers. The dark red color (garnet brown) of the Small Red market class materials was demonstrated to be produced by rk d, and the dark red color (oxblood) of `Jacobs Cattle' was demonstrated to be produced by R. A Light Red Kidney market class stock was derived from `Redkloud' and used in two crosses: c u b v rk BC1 5-593 × b v BC3 5-593 and c u b v rk BC1 5-593 × c u BC3 5-593. Classification of the F2 progenies demonstrated that the c u gene does not entirely prevent rk red color from being modified by V. The interactions of rk, rk d, and R with C, c u, G, B, and V are discussed, and previous literature concerning those interactions is critically reviewed.
Mark J. Bassett
Studying the genetics of seedcoat color in common bean (Phaseolus vulgaris L.) in F2 progenies is very difficult because of complex epistatic interactions, and the analysis is complicated further by multiple allelism, especially at the C locus. An alternative approach is to study seedcoat genetics by analyzing the F1 progeny of test crosses between a variety with unknown seedcoat genotype and genetic tester stocks with known genotypes. Twenty varieties, 18 with known genotype at C, were test crossed with the genetic tester stock c u BC3 5-593, where 5-593 is a recurrent parent with seedcoat genotype P [C r] D J G B V Rk. The resulting F1 progenies were classified into seven phenotypic classes and discussed. The crosses g B v BC3 5-593 × c u BC3 5-593 and c u BC3 5-593 × v BC3 5-593 were made and the F2 progeny classified for flower color and seedcoat color and pattern. No tiny cartridge buff flecks were observed in the segregants with C/c u v/v, whereas C/c u V/- always showed such flecks. The contrasting seedcoat color expression at C in different environmental conditions is discussed.
Douglas V. Shaw and Thomas R. Gordon
Strawberry (Fragaria ×ananassa Duch.) genotypes retained for resistance to Verticillium wilt (Verticillium dahliae Kleb.) after two cycles of a two-stage (TS) selection procedure consisting of full-sib family selection followed by within-family selection of individuals, and genotypes retained for resistance using genotypic mass (GM) selection were crossed to a common set of moderately susceptible genotypes. The relative resistance of the seedlings from these progenies was compared using a resistance score and the percentage of stunted plants. Although the two sets of resistant parents had performed similarly in genotypic comparisons, those genotypes selected using the TS procedure yielded test cross offspring with significantly higher resistance scores (X̄ = 3.84 ± 0.09 vs. X̄ = 3.46 ± 0.09, t = 3.11**) and significantly lower rates of plant stunting (X̄ = 38.1% ± 3.1 vs. X̄ = 50.2% ± 2.9, t = 2.87**) than the parents chosen using GM selection. Further resolution using analysis of variance and general combining ability (GCA) estimates showed that these between-set differences resulted from higher resistance breeding values for parents selected using the TS procedure. The five genotypes with largest GCA for resistance score and four of the five genotypes with minimum GCA for percentage stunting were obtained by TS selection.
Thierry Pascal, Fred Pfeiffer, and Jocelyne Kervella
families were produced by self-pollination of five F 1 hybrid plants and a pseudo-test cross (TC 1 ) population was generated by crossing one F 1 hybrid with ‘Big Top’® (clone 5811), a nectarine cultivar susceptible to powdery mildew with green foliage
Javier Sanzol and Timothy P. Robbins
the selection of incompatible combinations of cultivars when designing plantations or performing crosses in breeding programs ( Kester et al., 1994 ; Tehrani and Lay, 1991 ). Test-crosses to characterize cross-(in)compatibilities among cultivars
Ryan N. Contreras, John M. Ruter, and David A. Knauft
and also controls flower and petiole color. Test crosses and emasculation also suggested that all of the progeny produced in the current study developed through sexual hybridization and that all genotypes used in the study were self
Karen R. Harris, W. Patrick Wechter, and Amnon Levi
were used to screen for polymorphism in the parents of a watermelon test-cross mapping population previously developed and described by Levi et al. (2006) . The parents were Griffin 14113, ‘New Hampshire Midget’ (NHM), and PI 386015. PCR primers were
Júlia Halász, Attila Hegedűs, Zoltán Szabó, József Nyéki, and Andrzej Pedryc
. Crosspollination test. Crosses between cultivars with the putatively same S -genotype (‘Black Amber’ × ‘TC Sun’, ‘Black Amber’ × ‘Super Giant’, ‘Super Giant’ × ‘TC Sun’, ‘October Sun’ × ‘Super Giant’) were carried out in an orchard at Derecske, Hungary, in 2006
Bouchaib Khadari, Amal Zine El Aabidine, Cinderella Grout, Inès Ben Sadok, Agnès Doligez, Nathalie Moutier, Sylvain Santoni, and Evelyne Costes
F1 populations in tree species is the two-way pseudo-test cross-mapping strategy ( Grattapaglia and Sederoff, 1994 ) because it was efficient for mapping eucalyptus species ( Eucalyptus grandis W. Hill ex Maiden and E. urophylla S.T. Blake) and
Creighton L. Gupton
Anthocyanin-deficient dewberries in Mississippi were evaluated for possible use as a source of marker genes for blackberries. Ratios of normal to anthocyanin-deficient plants from test crosses suggested single-locus control of stem color, with anthocyanin deficiency a recessive trait. Its simple inheritance and easy identification in seedlings provide potential for anthocyanin deficiency (t) to be used as a marker gene in blackberry genetic studies.