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  • Author or Editor: Mark J. Bassett x
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The inheritance of two new induced mutations for spindly branch was investigated in common bean (Phaseolus vulgaris L.). Each mutant was found to be controlled by a recessive gene. Allelism tests were performed beween a previously reported spindly branch mutant (sb) and the two new spindly branch mutants; the new mutants were found to be nonallelic to sb and to each other. The gene symbols sb-2 and sb-3 are proposed for the new mutants. Repulsion phase F2 linkage tests were made for all nine combinations of reclining foliage (rf) and sb among the two mimic mutant series rf, rf-2, rf-3 and sb, sb-2, sb-3. No linkages were detected.

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A cross was made between gri (gray-white seedcoat) and p (pure-white seedcoat) using genetic stocks gri BC2 5-593 and p BC2 5-593 developed to carry only a single recessive allele for seedcoat color in an otherwise all-dominant genetic background. The recurrent parent, 5-593, is a Florida dry-bean breeding line with bishops-violet flowers, determinate habit, small seed size, shiny black seeds, and seedcoat genotype T Mar P [C r] D J G B V Rk. The F1 progeny from the above cross between gri and p had the flower color pattern and seedcoat color of the griseoalbus character (gri), but had less intense color expression. Therefore, I hypothesized that gri is an allele at the P locus (allelic interaction). The hypothesis of allelism was confirmed in the F2, which failed to segregate for bishops-violet flowers and black seed, i.e., no complementation was evident. The symbol p gri is proposed for the new allele at P, where the dominance series is P > p gri > p. The gene for gray-white seeds in gri BC2 5-593 was shown to be allelic to Lamprecht's gri gene in V0059 (PI 527716).

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The effects of gri on seed coat and flower color were investigated in a study using Lamprecht line V0400 (PI 527735) as the known source of gri. Seed and flower color data were taken on observations of F2, BC1-F2, and BC2,-F2 populations from crosses of V0400 with the recurrent parent S-593. Segregation was observed for a unique flower color pattern: wing petals have a very pale tinge of blue (laelia), and the banner petal has two violet dots (≈3- to 4-mm diameter) on a nearly white background. This very pale laelia flower color cosegregates with gray-white seed coats produced by gri. Furthermore, the very pale laelia color depends on the action of V for expression and is extinguished by v, which produces pure white flowers. Thus, it was demonstrated that the very pale laelia flower color, for which Lamprecht tentatively proposed the gene symbol vpal, is not controlled by an allele at V but is a pleiotropic effect of gri. It was also demonstrated that Lamprecht line V0060 (PI 527717) carries vlae, not v, as indicated by the genotypic notes accompanying the Lamprecht seed collection.

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Abstract

In strain gauge tests of sieve size 4 pods of snap bean (Phaseolus vulgaris L.), ‘Idelight’ and ‘Green Isle’ required the lowest pod detachment force (PDF) of 13 genotypes tested.

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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.

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Anecdotal evidence exists for nonflatulence among Chilean Manteca and Coscorrón market classes of common bean (Phaseolus vulgaris L.), and there is an hypothesis that the seedcoat color may be associated with superior digestibility. The inheritance of seedcoat color in `Prim', a Manteca market-class dry bean, was investigated using a protocol employing genetic interpretation of seedcoat colors in the F1 from testcrosses of `Prim' with a series of tester stocks. Most of the genetic tester stocks were constructed previously by backcrossing selected recessive alleles for seedcoat color into a recurrent parent (5-593) with seedcoat color genotype P [C r] D J G B V Rk Asp. The genetic tester stocks included two varieties, `Masterpiece' and `V0687', and testers constructed on the 5-593 background, viz., j BC2 5-593, d j BC2 5-593, asp BC2 5-593, b v BC2 5-593, v BC2 5-593, and c u BC3 5-593. The seedcoat color genotype of `Prim' was found to be P [C r] d j G b v lae. The implications of this genotype for pigment chemistry are discussed.

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The inheritance of an induced mutant for spindly branch and male sterility (SBMS) was investigated in common bean (Phaseolus vulgaris L.) in F2 and backcross populations. The results support the hypothesis that the mutant is controlled by a single recessive gene. Extensive breeding work with SBMS, involving several thousand F2 progeny, produced no recombinant of the types expected if two closely linked genes controlled the character. Therefore, a single pleiotropic gene apparently controls SBMS. Allelism tests demonstrated that SBMS is allelic with sb but not with sb-2 and sb-3. The gene symbol sb ms is proposed for SBMS because it is a new allele at sb, with the order of dominance being Sb > sb > sb ms . Various ways to exploit the new mutant for marked male sterility are discussed.

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Common bean (Phaseolus vulgaris L.) seedcoats can have partly colored patterns such as the new two-points pattern, which has an unknown genotype. The gene t cf (derived from PI 507984) expresses partly colored seedcoat pattern with colored flowers. A genetic tester stock t cf two-points BC3 5-593 was derived from PI 507984 by backcrossing to the recurrent parent, Florida dry bean breeding line 5-593, which has black self-colored seeds and purple flowers due to the genotype T P V. A series of test crosses were made between t cf two-points BC3 5-593 and three genetic tester stocks: t z j ers white BC3 5-593, t z bip bipunctata BC3 5-593, and t z virgarcus BC3 5-593. All three test crosses were studied in F1 and F2 populations, and the latter test cross in F3 progenies derived from 80 randomly selected F2 plants. The two-points pattern was never observed with white flower plants expressed by t/t, supporting the hypothesis that tcf is necessary for two-points expression. The complete genotype for two-points was found to be t cf z j ers. The t cf gene expresses more extensive colored zones in partly colored seedcoats than t. For example, t cf z J expresses self-colored seedcoats, whereas t cf/t z J expresses white ends pattern and t z J expresses virgarcus. Similarly, the t cf z j ers genotype expresses two-points pattern, whereas t z j ers expresses white seedcoat; and t cf/-z J/j ers expresses PI type pattern, whereas t z J/j ers expresses weak virgarcus pattern.

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The inheritance of intensified anthocyanin expression (IAE) in a syndrome of plant organs of common bean (Phaseolus vulgaris L.) was investigated. A selection from accession line G07262, having white flowers with blue veins on the wing petals and a long, white micropyle stripe on black seedcoats, was used as the source of IAE syndrome. G07262 was crossed with three genetic tester stocks based on Florida dry bean line 5-593, which has the flower and seedcoat genotype T P [C r] Z J G B V Rk. The tester stocks were 5-593 (black seed and bishops violet flowers), t z bip bipunctata BC1 5-593 (a partly colored seedcoat), and v BC2 5-593 (mineral brown seedcoat and white flowers). Analysis of the F1 and F2 data from the test cross G07262 × t z bip bipunctata BC1 5-593 demonstrated that 1) G07262 has genotype t p mic V; 2) genotype t/t prevents expression of IAE syndrome by a dominant gene (Prp i -2) carried cryptically by G07262, i.e., T/-is required for expression of the gene; and 3) Prp i -2 may (preliminary data) express blue veins on white flowers with t V. From the cross with v BC2 5-593, an F4 selection for white flowers with red banner back and mineral brown seedcoats (due to v) was made. When the F4 selection was crossed with 5-593, analysis of the F2 progeny demonstrated that G07262 carries a dominant gene for IAE syndrome, which expresses with V/- but not with v/v. From the test cross 5-593 × G07262, a series of additional cycles of selection and test crosses (including the dark red kidney tester c u b v rk d BC1 5-593) were made, and two new two-colored seedcoat patterns were developed that have never been previously reported. In a test cross with one of them, F2 data demonstrated that the dominant gene for IAE syndrome from G07262 is independent of the C locus, and the gene symbol Prp i -2 is proposed for this IAE syndrome gene to distinguish it from the previously reported IAE syndrome gene [c u Prp i]. A gene symbol reconciliation was made for all previous work with inheritance of IAE syndrome and purple pod genes without the syndrome.

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