lack of recombinant progeny makes pleiotropy a more likely scenario. The cosegregation of petiole and fruit color may be a useful tool in early screening of american beautyberry progeny. We used an EO treatment and reciprocal crosses between white- and
Ryan N. Contreras, John M. Ruter, and David A. Knauft
Samuel F. Hutton, John W. Scott, and Gary E. Vallad
bacterial spot sensitivity is the result of linkage to unfavorable alleles or to pleiotropy. If the former, a directed effort to select for recombination near the I-3 gene may prove successful in breaking the linkage, and the fine mapping efforts of Lim
Mark J. Bassett
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.
Mark J. Bassett
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.
Mark J. Bassett
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.
Rafael Gutiérrez-Campos, Juan Antonio Torres-Acosta, José de Jesús Pérez-Martínez, and Miguel Angel Gómez-Lim
A study was undertaken to evaluate possible phenotypic alterations in transgenic tobacco (Nicotiana tabacum L. cv. Xanthi) plants expressing the oryzacystatin I gene. Morphophysiologic parameters, such as growth rate, biomass, and leaf, flower, and fruit characteristics were analyzed. Transgenic plants overexpressing the cysteine proteinase inhibitor showed increased growth rate and dry weight, earlier flowering, and increased numbers of flowers and seeds. These pleiotropic effects were correlated with expression level of oryzacystatin I in transgenic lines. The results suggest that oryzacystatin I disrupts the normal activity of cysteine proteinases, which are involved in important physiological processes.
Joshua D. Williamson, Cameron P. Peace, Frederick A. Bliss, David T. Garner, and Carlos H. Crisosto
The Y locus of peach [Prunus persica (L.) Batsch] controls whether a tree will produce fruit with white or yellow flesh. Flesh color has implications for consumer acceptance and nutritional quality, and improved cultivars of both flesh types are actively sought. This paper focuses on evidence that the flesh color locus also controls senescent leaf color (easily observed in the fall) and hypanthium color. In two progeny populations totaling 115 progeny plus their parents, the three traits co-segregated completely. Trees carrying the dominant allele for white flesh had yellow senescent leaves and yellow hypanthia, while homozygous recessive yellow-fleshed types exhibited orange senescent leaves and orange hypanthia. Senescent leaf color was also measured quantitatively, with major colorimetric differences observed between white-fleshed and yellow-fleshed progeny. Senescent leaf hue angle and reflected light wavelengths of 500 to 560 nm were the parameters most affected by the flesh color locus. Results were verified with 10 white-fleshed and 10 yellow-fleshed cultivars. The findings show that the Y locus in peach controls the type and concentration of carotenoids in multiple organs, including fruit, leaves, and flowers. The ability to discriminate between white and yellow flesh color using a simple visual method, applicable in plants not yet at reproductive maturity, is valuable to breeders wanting to save time, growing space, and money.
Mark J. Bassett, Lee Brady, and Phil E. McClean
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.
M. Ndambe Nzaramba, Anna L. Hale, Douglas C. Scheuring, and J. Creighton Miller Jr.
The inheritance of antioxidant activity (AOA) and its association with seedcoat color was investigated in cowpea [Vigna unguiculata (L.) Walp.]. Four advanced cowpea lines, ARK95-356 (black seedcoat) and ARK98-348 (red seedcoat), which were high (H) in AOA, and ARK96-918 (cream seedcoat) and LA92-180 (cream seedcoat), which were low (L) in AOA, were selected from the 2002 Regional Southernpea Cooperative Trials. They were crossed in a complete diallel mating design, generating F1, F1′ (1st generation and 1st generation reciprocal cross, respectively), F2, F2′ (2nd generations from F1, F1′), BC1, and BC2 (backcrosses to parents 1 and 2, respectively) populations. Individual seeds were ground and samples were extracted in methanol and analyzed for AOA using the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Combining ability tests using Griffing's Method I Model I indicated presence of highly significant general combining ability (GCA), specific combining ability (SCA), and reciprocal (RE) and maternal (MAT) effects, with pigmented lines exhibiting positive GCA and MAT, while nonpigmented lines exhibited negative GCA and MAT. AOA in the F1 was not significantly different from the maternal parent, with seedcoat color also resembling the maternal parent. Segregation for seedcoat color was observed in the F2 and F2′. Additive, dominance, and epistatic effects were significant. The broad sense heritability estimate was 0.87. Minimum number of genes responsible for AOA was estimated at five. Factors governing high AOA appeared to be the same as those responsible for seedcoat color, with apparent pleiotropic effects. In conclusion, breeding for high AOA in cowpea is possible using highly pigmented parental lines.