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- Author or Editor: Mark J. Bassett x
Common bean (Phaseolus vulgaris L.) plant introduction 527829 (formerly Lamprecht M0048) has dark seal-brown (DSB) seedcoats and pink flowers. An investigation was conducted to determine the genotype of DSB seedcoat color. M0048 was crossed with Florida breeding line 5-593, which has genotype P [C r] D J G B V Rk. A series of crosses involving M0048, 5-593, and three genetic tester stocks (v BC2 5-593, c u BC2 5-593, and b v BC2 5-593) led to determination of the genotype. Data analysis indicated that M0048 has the genotype P [? R] J G B v lae, where DSB color is produced by the interaction of R with B. Crosses between [? R] and testers with [C r] always produced seedcoat mottling in F1, except where V masks the effect. The cross [? R] B v (DSB) × c u BC2 5-593 (cartridge buff seedcoat) produced marbled seedcoats (black/cartridge buff) with genotype [? R]/[c u ?] B V. No way was found to determine whether the mottled or marbled seedcoat patterns were controlled at C or R; hence, the allelic ambiguity is indicated with a question mark. Illustrations are provided showing the difference between seedcoat mottling (a highly variable low-contrast patterning) and seedcoat marbling (a less variable high-contrast patterning, usually with cartridge buff as the background color). The development of a new genetic tester stock, [? R] b v BC3 5-593, was described, where [? R] b v gives unpatterned dominant red seedcoat color.
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.
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.
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.
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.
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).
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.
Crosses were made with two common bean (Phaseolus vulgaris L.) parents that have pink flowers (v lae/-) and mineral-brown seedcoats with dark corona, viz., v lae BC3 5-593 (derived from Lamprecht V0491) and F3 v lae dark corona (derived from Lamprecht M0048). The third parent v BC2 5-593 had white flowers (v/v) and mineral-brown seedcoats without dark corona (derived from Lamprecht M0056). The F2 progenies of the crosses v BC2 5-593 × v lae BC3 5-593 and F3vlae dark corona × v BC2 5-593 segregated for only two phenotypic classes: either pink flowers and seeds with dark corona or white flowers and seeds without dark corona. Thus, it was demonstrated that the dark corona character (Cor) is either tightly linked to vlae (<4 map units) or is a pleiotropic effect of vlae. Pleiotropy is more probable, but tight linkage cannot be ruled out. A linkage of 15 map units between Cor and R (currently, R is known to be tightly linked with C) reported by Lamprecht was not found by subsequent authors, and the linkage map of common bean should be revised accordingly, i.e., no linkage exists between V (Cor) and C.
The inheritance of a seedcoat pattern having white micropyle stripe (WMS) on a colored background was studied in two common bean (Phaseolus vulgaris L.) accessions from Centro Internacional de Agricultura Tropical—G12606 and G07262. The WMS character from G12606 was backcrossed into the recurrent parent 5-593, which has black seedcoats. Test crosses of the derived WMS stocks (BC1 and BC2) with genetic tester stocks stp (stippled seedcoat) BC2 5-593 and stp hbw (flowers with half banner petal white) BC3 5-593, respectively, demonstrated in F1 and F2 progenies that WMS is controlled by an allele at the Stp locus. The gene symbol stp mic is proposed for the allele expressing the WMS character. The dominance order at the Stp locus is Stp > stp mic > stp hbw > stp. Although stp and stp hbw each produce a different color pattern on flowers, stp mic does not produce patterned flowers. A selection from accession G07262 with a long, white micropyle stripe was crossed with 5-593 to derive a stock named F3 stp mic long micropyle stripe, which was then crossed to the genetic tester stock t z virgarcus BC2 5-593 to produce F1 and F2. Expression of the long micropyle stripe was controlled by the interaction of t and stp mic in the genotype t Z stp mic. The triple recessive interaction from genotype t z stp mic was also observed.