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- Author or Editor: J.R. Myers x
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Tomato lines carrying the genes Aft, atv, Abg, hp-1, and an as yet undetermined gene from the introgression line LA2099 have been combined to produce fruit with elevated anthocyanin content. The antioxidant activity of juice made from anthocyanin-expressing tomatoes was compared to juices made from tomatoes with varied carotenoid content. The contribution of anthocyanin to the total antioxidant activity of the whole fruit in current material is small, but with potential for significant improvement. The increase in flavonoids in the elevated anthocyanin lines has increased water-soluble antioxidant activity of the fruit in vitro.
Genetic and morphological characteristics of an architectural mutant in common beans were studied. The mutant had shiny, dark green leaves, overlapping leaflets, short petioles and a terminal reproductive bud even though the line did not carry the fin gene. Branching was nearly absent, resulting in a single stem vine. This is a new form of determinancy in common bean. Inheritance studies demonstrated that the mutant trait was controlled by a single recessive gene. Allelism tests were performed between the mutant and a previously reported similar mutants, which were overlapping leaflets mutant (ol), and dark green savoy leaf mutant (dgs). Results showed that the mutant trait was not allelic to ol and dgs. As a temporary designation, the name “”opiary” describing its compact and neat appearance is being used. Linkage was tested for growth habit (fin), shiny leaf, cross-sectional shape of pods, striped pod (prpst ) and pod suture strings (st) with the topiary mutant. No linkages were detected between either the mutant and marker genes or among the marker genes. The topiary mutant has potential for improving common beans. Its single stem growth habit may allow closer row spacing leading to higher planting populations and may enhance the efficiency of mechanical harvest. Pod formation at higher nodes may escape disease. Currently, the thin stems cause lodging. Development of thick and upright forms will be the subject of future studies.
White mold, caused by Sclerotinia sclerotiorum (Lib.) de Bary, causes major losses in dry and snap bean (Phaseolus vulgaris) production. With little genetic variation for white mold resistance in common bean, other potential sources for resistance must be investigated. Accessions of scarlet runner bean (P. coccineus) have been shown to have partial resistance exceeding any to be found in common bean. Resistance is quantitative with at least six QTL found in a P. coccineus intraspecific resistant × susceptible cross. Our goal is to transfer high levels of resistance from P. coccineus into commercially acceptable common bean lines. We developed interspecific advanced backcross populations for mapping and transfer of resistance QTL. 111 BC2F5 lines from a cross between OR91G and PI255956 have been tested in straw tests and oxalate tests, as well as in a field trial. The data show that the OR91G × PI255956 population carries a high level of resistance, but because of the quantitative nature of resistance, it may be necessary to intercross individuals to achieve higher levels. SSR, RAPD, and AFLP markers are being tested in the population to construct a linkage map for placement of QTL. QTL identified from each type of test (straw, oxalate, and field) may provide additional information about the genetic architecture of white mold resistance. Three other populations are from advanced backcrosses of the recurrent parents G122, OR91G, and MO162, with PI433251B as the donor parent in each. Analyses and advance of these populations will follow, the results of which should confirm QTL identified in the OR91G × PI255956 population, as well as possible additional resistance QTL from PI433251B.
A nutritional study was initiated to determine which carotenoids found in tomato result in decreased lipid oxidation ex vivo. To compare the carotenoids in a human diet without the use of purified supplements, tomatoes expressing nonfunctional enzymes in the carotenoid pathway were used. Tomato lines carrying the genes t, B, ogc, Del, or r were grown to produce fruit containing with high levels of prolycopene, beta-carotene, lycopene, or delta-carotene respectively, or low total carotenoids in r. Juices were processed from these lines and used in a dietary intervention study. Plasma samples were drawn before and after consumption of each juice. These samples were subjected to a battery of tests to analyze the contribution of carotenoids to the total lipid antioxidant status. Results of these tests are discussed.
Hand-defoliation of field-grown `Golden Delicious' apple and `Bradford' pear nursery trees before autumn digging is a major production cost. One-year-old field-grown trees were sprayed to runoff on 18 Oct. 1994 with; 1) 1% FeEDTA, 2) 1% CuEDTA, 3) 1% ZnEDTA, 4) 100 ppm Harvade, 5) 50 ppm Dropp, 6) 500 ppm Folex, or 7) 2.5% EDTA or 8) leaves were removed by hand or 9) leaves left on trees (control). Treatments were arranged in a randomized complete-block design, with three trees/plot and four replications. Leaves on each tree were counted before treatment and 7, 14, 21, 28, and 35 days after treatment (DAT). One tree per plot was dug, stored until February and grown the following summer. Nontreated apple and pear trees had 13% and 38% defoliation, respectively, 35 DAT. CuEDTA treated apple trees had 62% and 93% defoliation 7 and 14 DAT, respectively. Pear trees treated with Cu had 18% and 100% defoliation 7 and 14 DAT, respectively. Treatment with FeEDTA resulted in 96% defoliation of pear within 7 DAT but only 57% defoliation of apple 35 DAT. ZnEDTA, Harvade, Folex, or Dropp did not significantly promote defoliation. Copper-treated apple trees had less budbreak than nontreated trees but similar budbreak as hand-defoliated trees. None of the treatments influenced budbreak of pear. None of the treatments affected the cumulative dry weight of trees at the end of the next growing season.