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Paul W. Bosland, Jaime Iglesias, and Max M. Gonzalez

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S.J. Scott, J. McFerran, and M.J. Goode

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James R. Baggett and R.O. Hampton

The inheritance of tolerance to infection by bean leaf roll luteovirus (BLRV) in Pisum sativum L. was studied in the cross of cv. Parlay (sensitive to BLRV infection) × cv. Oregon Sugarpod II (BLRV tolerant). The parents, reciprocal F1, back-crosses, F2, and 234 random F3 families were screened in 1986 and 1987 in the field at Twin Falls, Idaho, under natural BLRV inoculation by aphids. Overall disease index scores for the F1, F2, and F3 were about intermediate between indices of the parents, with the F1 usually slightly higher than midparent values. Backcross disease indices were intermediate between the F1 and the respective parent involved. Distribution of individual F3 family indices was continuous and semi-normal. BLRV-sensitivity ranges within parents and selected cultivars, as well as segregating populations showed continuous variation and differed between the 2 years, suggesting that expression of a major gene was significantly influenced by natural variation in BLRV inoculation pressure and timing. An apparent “additive gene action” was probably an artifact of nonuniform timing and levels of infection within plant populations. Chi-square analyses of segregating populations indicated that a major recessive gene, called lrv, conferred BLR disease tolerance.

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J.R. Baggett, D. Kean, and N.S. Mansour

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Wayne L. Schrader and Keith S. Mayberry

Open access

Alfred Jones

Abstract

Forty-five plants of sweet potato (Ipomoea batatas (L.) Lam.) taken randomly from the second cycle of a mass-selection population, and 25 open-pollinated progeny from each were used to estimate heritabilities (h2) of 7 root traits: root weight, 0.25 ± 0.13; intercellular space (IS), 0.70 ± 0.14; percent of dry matter (DM), 0.65 ± 0.12; sprouting, 0.39 ± 0.14; flesh oxidation, 0.24 ± 0.13; flesh color, 0.53 ± 0.14; and cortex thickness, 0.25 ± 0.13. IS was distributed normally with mean and mode of about 7%. DM had a bimodal distribution with mean 28.8 and modes of 27 and 31%. At least 2 genetic systems were apparently involved in expression of DM; one was associated with orange flesh and the other, with white flesh. This is the first report of the h2 for IS, DM, and sprouting.

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J. R. Baggett and D. Kean

Abstract

Immature white seedcoat (IW), consisting of reduced green color in immature seedcoats and early development of white color in white seeded cultivars of Phaseolus vulgaris, is described. IW was found in 9 of 66 commercial cultivars. It occurs irrespective of mature seedcoat colors, pod pigmentation, or wax vs. green pod color. Genetic analyses of progenies from 6 crosses indicated IW is conditioned by a single recessive gene which is not linked with the P locus for mature seedcoat color or with Y for green vs. wax pod. The gene designation iw is proposed for immature white seedcoat.