The inheritance of resistance to bean golden mosaic virus (BGMV) in common bean (Phaseolus vulgaris L.) was studied in crosses between susceptible bean variety XAN176 and resistant breeding lines 9236-6 (T446/A429) and 9245-94 (DOR303/T968). Disease response data were taken on plants from four generations derived from each cross (parents, F1, F2, and backcrosses (BCs) of F1 to both parents) at 25 days after plants were inoculated with BGMV, using whiteflies (Bemisia argentifolii Bellows & Perring) as vectors. The segregation ratios obtained from F2 and BC generations were consistent with the hypothesis that resistance in 9236-6, which prevents a chlorotic response, is conferred by a single recessive gene. The disease response in 9245-94 was controlled by two genes—a dominant gene controlling a dwarfing reaction and a recessive resistance gene preventing a chlorotic response to BGMV infection. An allelism test demonstrated that the gene controlling resistance in 9236-6 is nonallelic with the recessive gene controlling resistance in 9245-94. The gene symbol bgm is proposed for the recessive resistance gene (originally from A429) in 9236-6. The gene symbol bgm-2 is proposed for the recessive resistance gene (originally from DOR303) in 9245-94.
Jose J. Velez, Mark J. Bassett, James S. Beaver, and Albeiro Molina
Mark E. Lewis and Fred A. Bliss
Ten common bean (Phaseolus vulgaris L.) lines—including cultivars, breeding lines, and one wild line—were evaluated for susceptibility to Agrobacterium tumefaciens strain C58 by stab-inoculating intact shoot tips of germinating seeds. Significant differences for tumor frequency and size were found on the resulting 3-week-old seedlings. UW 325, a wild bean, had the highest rate of tumorigenesis; `Olathe', a dry bean cultivar, had the lowest. Uninoculated excised shoot tips cultured in media with BA or BA plus NAA exhibited differences in phytohormone sensitivity, as evidenced by callusing and root initiation. The cultivar Montcalm seemed to be highly sensitive, while `Olathe' was relatively insensitive. Fluorometric GUS assays of shoot tips from germinating seeds inoculated with the disarmed GUS-containing A. tumefaciens strain C58C1(pGV3850/pKIWI105) showed that UW 325 had the highest level of GUS activity. `Montcalm' had a high rate of tumorigenesis but a low level of GUS activity; this anomaly was attributed to its high phytohormone sensitivity. The use of the virulence-inducing compound acetosyringone in the inoculum culture medium did not alter genotypic differences (ranks) in susceptibility. Histochemical GUS assays of inoculated UW 325 shoot tips showed that 60% of the apexes exhibited one or more transformation events. Chemical names used: β-glucuronidase (GUS); α-naphthaleneacetic acid (NAA); N-(phenylmethyl)-1H-purin-6-amine (BA).
Paul H. Li
The common bean (Phaseolus vulgaris L.) is a heat-sensitive plant species in which excessive abscission of reproductive organs occurs during hot weather. This results in yield reductions, and, in extreme heat stress, plants produce few or no pods. We evaluated 74 bean genotypes in terms of leaf heat tolerance (HT) and leaf heat acclimation potential (HAP), as expressed by heat killing time (HKT), the time in minutes needed to cause a 50% electrolyte leakage from leaf tissue heated at 50°C Leaf HT is defined as the leaf HKT of plants without prior conditioning at 37°C day/night temperature and leaf HAP as the change in leaf HT following exposure of the plant to 37°C day/night for 24-h. Among 74 bean genotypes examined leaf HT ranged from 5 to 30 min HKT, whereas leaf HAP ranged from 35 to 130 min HKT. Positive significant correlations were observed between leaf HAP and post-stress performance in photosynthetic activities, plant dry weight, pod set, pod weight and yield among bean genotypes. Correlations, however, were not significant between leaf HT and post-stress performance.
A relationship between heat resistance, consisting of the combination of HT and HAP, and heat injury is proposed. Interpretation of the differential amounts of heat injury among genotypes having different HAP, is discussed. We view leaf HT and leaf HAP as two distinguishable phenomena. We suggest that in breeding programs HAP may be the more important of the two, and should he evaluated as a selection criterion for improving crop performance in high temperature environments.
Gino Beltran, Geunhwa Jung, Mark Bassett, and James Nienhuis
150 ORAL SESSION 42 (Abstr. 668–674) Breeding & Genetics–Vegetables
Marko Maras, Jelka Šuštar-Vozlič, Wolfgang Kainz, and Vladimir Meglič
Common bean is by far the most widely consumed grain legume in the world ( Singh, 2001 ). Domestication of common bean took place in two, already diverged ancestral wild gene pools distributed from northern Mexico to Colombia (Mesoamerican gene pool
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, Rian Lee, Carla Otto, and Phillip E. McClean
Inheritance of the strong greenish-yellow (SGY) seedcoat color in `Wagenaar' common bean (Phaseolus vulgaris L.) was investigated. 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, e.g., g b v BC3 5-593. Through crosses with genetic tester stocks, the seedcoat genotype of `Wagenaar' was confirmed to be C J g b v lae Rk. Three randomly amplified polymorphic DNA markers (OAP7850, OAP31400, and OU14950) that cosegregated with the G seedcoat color locus were developed from the F2 population derived from the cross g b v BC2 5-593 × G b v BC3 5-593. From the cross `Wagenaar' × g b v BC3 5-593, 80 F2 plants were classified into 54 non-SGY and 16 SGY seedcoat color plants. When the OAP7850 marker was applied to that population, linkage was not observed with the non-SGY and SGY phenotypes. Conversely, a molecular marker (OAP12400, that was developed from the F2 from the cross `Wagenaar' × g b v BC3 5-593) linked to the locus controlling the SGY phenotype segregated independently of the G locus. Therefore, SGY phenotype is not controlled by the G locus. An F3 progeny test of 76 F2 plants from the cross `Wagenaar' × g b v BC3 5-593 confirmed the hypothesis that a single recessive gene (for which we propose the symbol gy) controls the seedcoat color change from pale greenish yellow (PGY) to SGY. Through crosses with genetic tester stocks, the seedcoat genotype of `Enola' was determined to be C J g b v lae Rk. The test cross `Enola' × `Wagenaar' demonstrated that `Enola' also carries the gy gene. The relationship of `Enola' to the `Mayocoba' market class of common bean and to `Azufrado Peruano 87' is discussed.
Clifford W. Beninger, George L. Hosfield, Mark J. Bassett, and Shirley Owens
Three common bean (Phaseolus vulgaris L.) seedcoat color (or glossiness) genotypes, differing from each other by a single substitution at a seedcoat locus, were analyzed for presence and concentration of three anthocyanins: delphinidin 3-O-glucoside, petunidin 3-O-glucoside, and malvidin 3-O-glucoside. The three anthocyanins were present in Florida common bean breeding line 5-593 (P C J G B V Asp), matte black (P C J G B V asp), and dark brown violet (P C J G b V Asp), but the amounts varied greatly depending on the genotype. Dark brown violet had 19% of the total anthocyanin content when compared to 5-593, whereas matte black had amounts intermediate between the two other genotypes. The B gene acts to regulate the production of precursors of anthocyanins in the seedcoat color pathway above the level of dihydrokaempferol formation, perhaps at the chalcone synthase or chalcone isomerase steps in the biosynthetic pathway. We hypothesize that B regulates simultaneously the flavonoid (color) and isoflavonoid (resistance) pathways. The I gene for resistance to bean common mosaic virus (BCMV) is known to be linked closely to B. It is therefore hypothesized that the I gene function may be to respond to BCMV infection by dramatically increasing (over a low constituitive level) production in the 5-dehydroxy isoflavonoid pathway, which leads to synthesis of the major phytoalexin, phaseollin, for resistance to BCMV. Alternatively, the B and I genes may be allelic. The Asp gene affects seedcoat glossiness by means of a structural change to the seedcoat. We demonstrate that Asp in the recessive condition (asp/asp) changes the size and shape of the palisade cells of the seedcoat epidermis, making them significantly smaller than either 5-593 or dark brown violet. Asp, therefore, limits the amounts of anthocyanins in the seedcoat by reducing the size of palisade cells.
Kimberly J Walters, George L. Hosfield, and James D. Kelly
30 POSTER SESSION 4 (Abstr. 460-484) Breeding/Genetics/Molecular Markers
Mark J. Bassett and Mathias J. Silbernagel
Dry seed of the common bean (Phaseolus vulgaris L.) breeding line S-593 was treated with 200 Gy of gamma radiation, and M2 seed was produced. The seed was planted at Prosser, Wash., and selection was made for plants with greatly reduced seed set. The inheritance of one of the selections for possible male sterility mutation was studied in F2, F3, and backcross generations. This character is controlled by a single recessive gene, for which the symbol ms-1 is proposed. Plants carrying ms-l/ms-1 produce well-filled pods after manual pollination with pollen from normal plants, but produce no seed when protected from insect pollination in greenhouse and field environments. Uses for this mutant are discussed.