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.
Mark J. Bassett
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.
Mark J. Bassett
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.
Mark J. Bassett
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.
Maria Fisher, David Eissenstat, and Jonathan Lynch
In annual plant species, root death has been assumed to be closely correlated with shoot senescence. However, in a preliminary study with common bean grown in sand culture beyond physiological maturity (114 days), no root death occurred. We investigated whether the incidence of bean root death was higher under field conditions than in sand culture. Root death was defined as root disappearance. The sand culture consisted of silica sand and P-loaded alumina. Plants in this system were fertigated twice daily with complete nutrients supplied in adequate amounts. The field planting was on a Hagerstown silt loam in central Pennsylvania. Roots were observed using minirhizotrons every 1 to 3 weeks after planting. In sand culture, incidence of root death was monitored on a population of 170 roots from three plants between 25 and 88 days (shoot senescence) after planting Root death was 10%. In the field study, 55% of the 53 roots examined died between 32 and 93 days (shoot senescence) after planting. Biological factors present in the field and not present in sand culture appeared to contribute to root death. The persistence of roots in sand culture suggests a lack of programmed root senescence in contrast to shoot senescence. This has interesting implications for resource allocation during reproduction and in face of belowground herbivores and pathogens.
Mark J. Bassett
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.
James D. Kelly and Veronica A. Vallejo
constructive comments during the preparation of this manuscript. Support from the USAID Bean/Cowpea Collaborative Research Support Program grant DAN 1310-G-SS-6008-00 and the Michigan Agricultural Experiment Station is recognized.
Phillip D. Griffiths, Eric Sandsted, and Donald Halseth
evaluation in multistate greenhouse and field comparisons through the W-2150 regional project. White mold is an important disease of common bean worldwide reducing both yield and quality of seed harvested. Plant protection from white mold can be conferred
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.
Mark J. Bassett and Phillip N. Miklas
Among light red and dark red kidney common bean (Phaseolus vulgaris L.) varieties, pink seedcoat color (light red kidney) is dominant to dark red, but when Red Mexican varieties (with dark red seedcoats) are crossed with dark red kidney varieties, dark red seedcoat is dominant to the pink segregants observed in an F2 population. A genetic investigation of this reversal of dominance was performed by making crosses in all combinations among standard varieties of the four recessive-red market classes—Light Red Kidney `California Early Light Red Kidney', Pink `Sutter Pink', Red Mexican `NW 63', and Dark Red Kidney `Montcalm'—and observing segregation for seedcoat colors in F2 and F3 progenies. The data were consistent with the hypothesis that `NW 63' carries a new allele at Rk, viz., rk cd, where cd stands for convertible dark red kidney. Thus, C rk cd expresses dark red kidney seedcoats and c u rk cd expresses pink seedcoats. Also, C B rk cd expresses garnet brown seedcoats, whereas C B rk d expresses liver brown seedcoat color. Thus, we propose the gene symbol rk cd for the Rk locus gene in `NW 63'. The rk gene from Light Red Kidney `Redkloud' and `Sutter Pink' was backcrossed (with c u b v) into the recurrent parent 5-593, a Florida dry bean breeding line with seedcoat genotype P [C r] J G B V Rk. In the F2 progenies of BC2 to 5-593, the c u b v rk segregants from `Redkloud' gave true pink seedcoats, whereas those derived from `Sutter Pink' gave consistently very weak pink color under humid Florida growing conditions. We propose the gene symbol rk p, where p stands for pale pink, for the distinctive rk allele in `Sutter Pink'. The more general implications of the above findings were discussed.