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  • Author or Editor: D.P. Coyne x
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The potato leafhopper (PLH), Empoasca fabae Harris is the most important Empoasca species attacking dry beans (Phaseolus vulgaris L.) in North America. The objective of this study was to determine the heritability (h2) of PLH injury based on parent-offspring regression analysis of F3 means on individual F2 plants derived from crosses of pinto `Sierra' (resistant) × great northern `Starlight' (susceptible), and black bean `Tacarigua' (resistant) × `Starlight' (susceptible). Low narrow-sense heritability values of 0.29 ± 0.06 and 0.28 ± 0.10, respectively, were obtained for the above crosses. The low narrow-sense heritability estimates indicated large environmental effects on the expression of PLH injury in dry beans. An allelic test showed that both resistant parents possessed the same genes for resistance.

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Abstract

Belneb Rust Resistant-1 and -2 (Belneb RR-1 and -2), are two medium-large, white-seeded, viney, Great Northern (GN) dry bean (Phaseolus vulgaris L.) germplasm lines and are the first dry bean lines homozygous for resistance to 33 races of the bean rust pathogen [Uromyces appendiculatus (Pers.) Ungar var. appendiculatus] [= U. phaseoli (Reben) Wint.] recently identified (6, 7) from the United States and the Caribbean. These lines were approved for joint release by ARS/USDA, and the Nebraska Agricultural Experiment Station in Apr. 1988. Although nearly 200 races of U. appendiculatus have been identified worldwide (7), the 33 used here (races 38-70) are the only races virulent for several of the most broadly rust-resistant bean germplasm (6, 7).

Open Access

An association between abaxial leaf pubescence (ALP) and adult plant resistance (APR) on trifoliolate leaves was reported previously. Recombinant inbred (RI) lines from crosses PC-50 (P1) with XAN-159 (P2) and BAC-6 (P3), and P3 with HT7719 (P4) were used to study the inheritance of specific resistance (SR), APR and ALP. P1 is resistant to A88TI-4b and has abaxial hairs on the trifoliolate leaves while P2, P3, and P4 are all susceptible (S) and have glabrous (G) leaves. P3 is resistant to D85C1-1. SR to A88TI-4b on primary leaves (PL) was determined by a single dominant gene with an additional dominant gene for APR on the 4th trifoliolate leaves in P1 × P2. ALP was governed by a single dominant gene with no association with APR. SR to A88TI-4b on PL in P1 × P3 was controlled by a single dominant gene. SR to DC85C1-1 on the PL was determined by a single dominant gene in P3 × P4.

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Twenty-four diverse bean (Phaseolus vulgaris L.) lines (Malawi) derived from single plant selections from landraces were evaluated for bean rust (Uromyces appendiculatus) resistance and leaf pubescence in the greenhouse (NE). A randomized complete block design was used. Each line was inoculated on the primary leaf (35-60% leaf expansion) 7 days after planting and on the 4th trifoliolate leaf (10-20% leaf expansion) with two rust strains, D82VC74fh(Dominican Republic) and A88TI-20a (Tanzania). Rust uredinia size was recorded on the 14th day after inoculation. Three lines, `Nasaka', 16-6, and `Kamtsilo' had specific resistance (SR) to one or the other of the strains but none to both strains. Many lines were susceptible on the primary leaves but had moderate to highly resistant reactions on the 4th trifoliolate leaves indicating adult plant resistance (APR). APR was the main type of rust resistance for most of these 24 lines. Many of these APR lines were glabrous. No association was observed between APR and pubescence.

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Abstract

Common blight, caused by the bacterium Xanthomonas phaseoli (E. F. Smith) Dowson, is one of the most serious seed-borne diseases of bean, Phaseolus vulgaris L. Recommended controls are use of certified, diseasefree seed and crop rotation; there is no satisfactory chemical control.

Open Access

Bacterial brown spot (BBS), incited by the bacterial pathogen Pseodomonas syringae pv. syringae is important disease of common bean. Phenotypic visual readings of infected areas and a leaf freezing assay estimating the population size of Pss on leaf surface were used for disease assessment for 2 years using 78 RI lines derived from Belneb RR-1 x A55 population grown in Wisconsin. The objectives of this research were to determine the genomic regions of QTL affecting the genetic variation of bacterial brown spot resistance in both assays over 2 years (1996 and 1998) and to determine the size of their genetic effects. In addition, we examined the consistency of detected QTL over environments. Three chromosomal regions associated with QTL for BBS resistance were identified in both assays in 1996 and one chromosomal region was consistently detected over 2 years.

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Common bacterial blight (CBB) in common bean (Phaseolus vulgaris L.), caused by Xanthomonas campestris pv. phaseoli (Xcp), reduces bean yields and quality throughout the world. Pinto `Chase' is a high-yielding variety with moderate resistance to Xcp derived from great northern Nebraska #1 selection 27, whose resistance is derived from an unknown tepary (P. acutifolius) bean source. XAN-159 is a black mottled small seeded breeding line with different genes for high resistance to Xcp derived from a different tepary source (PI 319443). Our objective was to pyramid different genes for Xcp resistance from the donor parent XAN-159 into the rust-resistant recurrent parent Pinto `Chase' using the classical back-cross breeding method with confirmation of resistance using RAPD molecular markers. Resistance was confirmed in some BC2F2 generation plants. Seven RAPD markers and the V locus (flower color) previously identified were confirmed in the BC1 and BC2 populations. Smaller seed size, purple flower color, and black mottled seed coat color were coinherited with resistance to Xcp. However, a recombinant plant with enhanced CBB resistance and moderate-sized pinto seed was identified. Backcross breeding is being continued.

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We studied leaf and pod reactions of 18 Phaseolus vulgaris germplasm lines (three temperate and 15 tropical) to four Xanthomonas campestris pv. phaseoli (XCP) (Smith) Dye strains and seven Uromyces appendiculatus (UA) (Pers.) Unger races. Line × XCP interaction was significant for leaf and pod reactions. The common bean lines XAN-159, BAC-6, and XAN-112 had the best combined leaf and pod resistance to XCP. Line × UA race interactions were significant (P = 0.05). Lines IAPAR-14 and BAC-6 had the best combined resistance to XCP and UA.

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