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  • Author or Editor: Phil McClean x
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Inheritance of two phenotypes, the virgarcus pattern of partly colored seedcoats and the margo d seedcoat pattern, were studied in common bean (Phaseolus vulgaris L.) materials that segregated jointly for genes controlling the two phenotypes to test the hypothesis of allelism of two genes, D and Z. The F2 progeny from the cross j margo BC3 5-593 × t z virgarcus BC3 5-593 produced an unexpected phenotypic class, margo d, suggesting possible allelism of D and Z. The F2 also produced another unexpected phenotypic class, white seedcoat, for which the genetic hypothesis t j z was made. The F2 from the cross t j marginata BC3 5-593 × t z virgarcus BC3 5-593 provided supporting evidence for the new genotype, t j z, for a white seedcoat. Analysis of the F2 and F3 progenies of 80 random F2 plants from the cross t z virgarcus BC3 5-593 × d j (margo d) BC3 5-593 provided support for the hypothesis that the D and Z loci are allelic. Production of two different phenotypes (white vs. white with two tiny pale gray dots, one each at the raphe and micropyle) for t J/j z in two different genetic and cytoplasmic backgrounds is discussed. The F2 from the crosses d j (margo d) BC2 5-593 × j v margo BC2 5-593 and d j (margo d) BC3 5-593 × j margo BC3 5-593 segregated for d (vs. D) phenotypes, which were found not to be independent of a randomly amplified polymorphic DNA (RAPD) marker (AM10560) associated (1.4 cM) with the Z locus. Because the Z gene symbol has priority, we propose to retain Z for the locus.

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Inheritance of Anasazi pattern of partly colored seedcoats in common bean (Phaseolus vulgaris L.) was studied in a genetic stock t ana B V Anasazi BC3 5-593, whose Anasazi pattern is derived from Plant Introduction (PI) 451802. Line 5-593 is a determinate, Florida dry bean breeding line (with small black seeds) used as the recurrent parent in the development of many genetic stocks. The F2 from the cross t ana B V Anasazi BC3 5-593 × t z virgarcus BC3 5-593 segregated for two nonparental phenotypic classes and was consistent with the hypothesis that a single recessive gene, with tentative symbol ana, produces the Anasazi pattern with t Z ana and a new partly colored pattern Anabip with t z ana. Thus, the Anasazi factor is not an allele at the Z locus. Analysis of 57 random F3 progenies from the cross t ana B V Anasazi BC3 5-593 × t z virgarcus BC3 5-593 supported a genetic model where: 1) with t Z the Anasazi phenotype is controlled by a single recessive gene ana, i.e., genotype t Z ana, 2) the Anabip phenotype has the genotype t z ana, and 3) t Z/z ana produces a restricted Anasazi pattern. The allelism test cross t z ana Anabip BC3 5-593 × t z l ers white BC3 5-593 produced complementation in the F2, demonstrating nonallelism of Ana (actually Bip) with the L locus. The allelism test cross t z ana Anabip BC3 5-593 × t z bip bipunctata BC3 5-593 failed to show complementation in F1 and F2, demonstrating allelism of Ana with the Bip locus. Using bulk segregant analysis, molecular markers linked in coupling to the Ana (OM9200, 5.4 cM) and Bip (OJ17700, 6.0 cM) genes were discovered. Allelism was also suggested by the result that the same linkage distance and recombination pattern were observed when the Ana marker was used to score the bipunctata population. We propose the gene symbol bip ana for the recessive allele at the Bip locus that produces Anasazi pattern with genotype t Z bip ana and the Anabip pattern with genotype t z bip ana. Although bip ana and bip are both recessive to Bip, their interactions with the Z locus are extraordinarily different. The pattern restrictive power of bip ana expresses partly colored pattern with t Z, whereas bip requires t z to express partly colored pattern.

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Common bean (Phaseolus vulgaris L.) plants with partly colored seeds and colored flowers were derived from PI 507984 in two genetic tester stocks, `2-points t cf BC1 5-593' and `2-points t cf BC2 5-593'. These stocks were produced 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. The crosses `2-points t cf BC1 5-593' × 5-593 and `2-points t cf BC2 5-593' × 5-593 produced F2 populations in which all plants had colored flowers. Those results, when considered with previously published work, do not support the previously reported hypothesis that the genes t Fcr Fcr-2 produce partly colored seedcoats and flower color restoration with t. The crosses `2-points t cf BC1 5-593' × `self-colored t BC2 5-593' and `2-points t cf BC2 5-593' × `minimus t BC3 5-593' produced F2 populations that segregated 3:1 for colored:white flowers, respectively. Those results are consistent with the revised hypothesis that t cf can produce partly colored seedcoats without affecting flower color. The RAPD marker OM19400, which is linked in repulsion to T, was used with the F2 populations from the crosses `2-points t cf BC2 5-593' × 5-593 and `2-points t cf BC2 5-593' × `minimus t BC3 5-593' and established that the t cf gene from PI 507984 is either an allele at T or tightly linked to T. F3 data from the cross `2-points t cf BC2 5-593 × 5-593 also support the t cf hypothesis. On the basis of the above experiments, the gene symbol t cf is proposed for an allele at T that pleiotropically produces partly colored seeds and colored flowers.

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Snap bean (Phaseolus vulgaris L.) breeding programs are tasked with developing cultivars that meet the standards of the vegetable processing industry and ultimately that of the consumer, all the while matching or exceeding the field performance of existing cultivars. While traditional breeding methods have had a long history of meeting these requirements, genetic marker technology, combined with the knowledge of important quantitative trait loci (QTL), can accelerate breeding efforts. In contrast to dry bean, snap bean immature pods and seeds are consumed as a vegetable. Several pod traits are important in snap bean including: reduced pod wall fiber, absence of pod suture strings, and thickened, succulent pod walls. In addition, snap bean pods are selected for round pod cross section, and pods tend to be longer with cylindrical seed shape. Seed color is an important trait in snap bean, especially those used for processing, as processors prefer white-seeded cultivars. The objective of this study was to investigate the genetic control of traits important to snap bean producers and processors. RR6950, a small seeded brown indeterminate type IIIA dry bean accession, was crossed to the Oregon State University (OSU) breeding line OSU5446, a type I Blue Lake four-sieve breeding line to produce the RR138 F4:6 recombinant inbred (RI) mapping population. We evaluated the RR138 RI population for processing and morphological traits, especially those affecting pods. The RR138 population was genotyped with the BARCBean6K_3 Beadchip, and single nucleotide polymorphisms (SNPs) were used to assemble a linkage map, and identify QTL for pod traits. The linkage map produced from this study contained 1689 SNPs across 1196cM. The map was populated with an average of one SNP per 1.4 cM, spanning 11 linkage groups. Seed and flower color genes B and P were located on Pv02 and Pv07, respectively. A QTL for string:pod length (PL) ratio was found on Pv02 controlling 32% of total genetic variation. QTL for a suite of important processing traits including pod wall fiber, pod height, pod width, and pod wall thickness were found clustering on Pv04 and controlled 21%, 26%, 18%, and 16% of genetic variation for each of these respective traits. A QTL for PL was found on Pv09 controlling 5% of genetic variation.

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