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  • Author or Editor: Mark J. Bassett x
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The P locus in common bean (Phaseolus vulgaris L.) can express complete absence of color (white) in seedcoats and flowers with p (with B V) or a pale grayish white seedcoat and nearly white flower with p gri, but P has never been considered a seedcoat pattern locus. Genes controlling seedcoat colors and patterns have been backcrossed into the recurrent parent 5-593 with black seedcoats and violet flowers. The cross, p BC3 5-593 × t stp mic BC3 5-593 (black seeds with a long white micropyle stripe and fibula arcs), failed to show evidence of genetic complementation in either F1 or F2 progeny, leading to the hypothesis that P and Stp are allelic. Five cross combinations between two recessive P alleles (p BC3 5-593 and p gri BC3 5-593) and three recessive alleles at the stippled seedcoat gene Stp (stp BC3 5-593, stp hbw BC3 5-593, and stp mic BC3 5-593) expressed no genetic complementation in seedcoats and flowers of F1 progeny and confirmed the allelism hypothesis. New gene symbols are proposed for the recessive alleles at Stp, viz., p stp for stp, p hbw for stp hbw and p mic for stp mic. The dominance order at P is P > p mic > p hbw > p stp > p gri > p. Crosses were made between t self-colored BC3 5-593 and three other parents—p stp BC3 5-593, p hbw BC3 5-593, and p mic BC3 5-593—to explore interactions between the pattern genes T and P; and segregation for seedcoat patterns in F2 was discussed. The hypothesis was proposed that the T locus regulates expression at P, or the biosynthetic step regulated by P.

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The genetics of the vermilion flower color (more orange than scarlet or salmon red) of Phaseolus coccineus L. is largely unknown, but the gene Sal for salmon red is the gene essential for its expression. Lamprecht line M0169 (PI 527868) expresses salmon red flowers with vein pattern on the wing petals and black seedcoats. M0169 (Sal Am and an unknown gene that inhibits the scarlet flower color expression of Am) was crossed with v BC3 5-593 (sal am and no inhibitor gene, expressing white flowers and mineral brown seedcoats). Line 5-593 is a Florida dry bean (Phaseolus vulgaris L.) line used as the recurrent parent for development of genetic stocks. The F2 from Sal Am V wf BC1 5-593 (scarlet flowers, black seedcoats) × v BC3 5-593 (white flowers, mineral brown seedcoats) supported the hypothesis that a partly dominant gene Am changes salmon red to scarlet flower color and that Am has no expression with sal. The F3 progeny test of 27 random F2 parents from the above cross supported the hypothesis of a single partly dominant factor (Am) with no expression without Sal, where only Sal/Sal Am/Am completely eliminates the flower vein pattern (VP) of Sal. F4 progeny tests of 29 random F3 parents derived from a F2 selection with Sal/Sal Am/am V wf/v supported the hypothesis that Am is linked to V (cM = 9.4 ± 1.93) and the hypothesis that Am is linked with a dominant gene (tentative symbol Oxb) that (with Sal v) changes seedcoat color from mineral brown with red haze to oxblood red. Another F4 progeny test of seven selected F3 parents with Sal/Sal Am/am v/v and oxblood seedcoat color supported the hypothesis that the Oxb gene (linked with Am and derived from M0169) with Sal v expresses oxblood seedcoat color. The gene symbol Am is proposed for the gene from M0169 that with Sal v expresses two pleiotropic effects: changes salmon red to scarlet flower color and eliminates the VP of salmon red. The interaction of Sal with Am for flower color and VP expression is discussed for all gene combinations.

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The inheritance of corona and hilum ring color of common bean (Phaseolus vulgaris L.) was investigated in the reciprocal cross `Wagenaar' (a Canario market class dry bean) × `Mayocoba' (Mayocoba market class dry bean), where both parents were known to have seedcoat color genotype P [C r] gy J g b v lae Rk. `Wagenaar' has greenish yellow (GY) seedcoat (due to gy) except for purple (dark) corona (due to v lae) and reddish brown hilum ring (due to J), whereas `Mayocoba' has an entirely GY seedcoat. Seeds produced on the F1 progeny plants had GY corona and reddish brown hilum ring. The F2 segregated for three phenotypic classes, the two parental classes and the F1 class, but the segregation did not fit a 1:2:1 segregation ratio due to disturbed segregation. F3 progeny tests of 35 randomly selected F2 parents demonstrated that the two parental classes were true breeding and the F1 class segregated again (as in the F2) for the same three phenotypic classes. In spite of variable expressivity of GY color and disturbed segregation, the data support a single gene hypothesis, for which the tentative symbol Chr is proposed. Chr is dominant for changing purple corona to GY, but recessive for changing reddish brown hilum ring to GY. Thus, only one gene, Chr, controls the difference in seedcoat color between the market classes Canario and Mayocoba. An allelism test between Chr and Z (hilum ring color factor) is needed before a formal proposal for Chr can be made.

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An inheritance study was conducted with genetic stocks constructed in the genetic background of the recurrent parent 5-593, a Florida dry bean (Phaseolus vulgaris L.) breeding line with black seeds and purple flowers and genotype P T Z l +. The genetic stocks, t ers ers-2 BC3 5-593 (pure white seeds), t virgarcus BC3 5-593, and t BC2 5-593 self-colored were constructed by backcrossing selected recessive alleles for partly colored seedcoats into 5-593. The cross t ers ers-2 BC3 5-593 × t BC2 5-593 self-colored was studied in F1, F2, and F3. The observed data supported the hypothesis that ers is a synonym for z and that ers-2 is a synonym for a new allele (l ers) at the L locus. The cross t ers ers-2 BC3 5-593 × t virgarcus BC3 5-593 was studied in F1 and F2 progeny, and the results confirmed the hypothesis of allelism between ers and z. `Thuringia' (pure white seedcoats) with genotype P t z L was crossed with t ers ers-2 BC3 5-593, t virgarcus BC3 5-593 and t BC2 5-593 self-colored. The cross `Thuringia' (P t z L) × t ers ers-2 BC3 5-593 was studied in F1 and F2 and supported the hypothesis that l ers is an allele at L. The results of the other two test crosses are discussed. The gene ers-2 is a new recessive allele at L, for which the new symbol l ers is proposed. Thus, the dominance order at the L locus is L > l + > l ers, where l + is the null allele at L found in 5-593. The l + allele does not restrict the colored area of a partly colored seedcoat and is hypothetically the wild-type allele at L.

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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.

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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.

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The inheritance of novel flower and seedcoat patterns was studied in three parental materials: PI 390775 and `Springwater Half Runner' (SHR), which have patterned flower and seedcoat colors, and 5-593, a Florida dry bean breeding line with unpatterned purple flowers and seeds. Using crosses between 5-593 and the other two parents, an analysis of F1, F2, backcross F2, and backcross F3 data demonstrated that a single recessive allele in each of the patterned parents controlled flower and seedcoat pattern. Genetic tester stocks were used to demonstrate that the recessive gene for patterning in PI 390775 was nonallelic with C, T, and Mar, the three genes previously known to control seedcoat pattern in common bean. An allelism test between the recessive pattern genes from PI 390775 and SHR demonstrated that they were allelic and that the gene from SHR was dominant. The gene symbols stp (for the gene from PI 390775) and stp hbw (for the dominant gene from SHR) are proposed, where stp stands for stippled seedcoat pattern and the superscript letters hbw stand for half banner white.

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Linkage relationships between the locus for shiny pods (ace) and the loci for reclining foliage (rf) and pink (v lae) or white (v) flower color were studied in several crosses among common bean (Phaseolus vulgaris L.) parents. Florida dry bean breeding line 5-593 (Ace Rf V.) was crossed with F3 ace/ace Rf/rf V/v lae, and data were taken in F2. Selections from the previously mentioned F2, viz., F3 ace Rf V, F3 ace rf v lae plant no. 1 and F3 ace rf v lae plant no. 2, were backcrossed to 5-593. Data were taken in F2 on segregation for pod, foliage, and flower characters. Linkage between Ace and V was 37 map units (cM), and linkage between Ace and Rf was 31 cM. A revised estimate for the linkage between Rf and V was 11 cM. The map orientation for linkage group VII is ace -31-rf-11-V.

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The inheritance of flower and seedcoat color was studied using Lamprecht line M0137 (PI 527845) of common bean (Phaseolus vulgaris L.) as the source of a new allele, V wf, at the V locus. The cross M0137 c res V wf × C v BC2 5-593 (a genetic tester stock) was studied in progeny of the F1, F2, F3, and F4 generations. The observed segregation for flower and seed colors was consistent with the hypothesis that M0137 carried a new allele, V wf, that produced (in the presence of P C J G B) white flowers and black seeds rather than the white flowers and mineral-brown seeds produced (in the presence of P C J G B) by v. The V/V wf genotype produced cobalt-violet flowers, the same as V/v. A test cross of F3 V wf × t BC1 5-593 bipunctata demonstrated that V wf is not allelic with t, a gene that can produce white or colored flowers and self-colored or partly colored seeds, depending on background genotype.

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Linkage between the Fin locus controlling plant habit and the Z locus controlling partly colored seedcoats in common bean (Phaseolus vulgaris L.) was studied in the F2 and F3 progenies from the cross `t virgarcus BC3 5-593' (determinate habit, virgarcus pattern of partly colored seeds, fin tz) × `Steuben Yellow Eye' (indeterminate habit, sellatus pattern of partly colored seeds, Fin t z sel). The heterozygous genotype z sel/z produces the piebald pattern of partly colored seeds, whereas Fin is completely dominate to fin. Selection was made in the F2 for crossover phenotypes: indeterminate habit with virgarcus seeds or determinate habit with piebald seeds. Linkage calculations were based on crossover genotypes confirmed by F3 progeny tests grown in the greenhouse. The recombination percentage between Fin and Z was 1.032±0.33 map units. The gene symbol z sel is proposed, where t Z gives the expansa partly colored seedcoat pattern, t z sel gives sellatus, and t z gives virgarcus.

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