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Ten dry bean (Phaseolus vulgaris L.) cultivars/lines with differential reactions to rust were used in growth chamber experiments to determine rust [Uromyces appendiculatus (Pers.) Unger var. appendiculutus, (U a)], and common bacterial blight Xanthomonas campestris pv. phaseoli (E.F. Sm.) Dews. (X c p)] reactions on leaves when coinoculated with both pathogens. The X c p-U a necrosis symptoms were very different from those caused by X c p alone. Depending on the level of host susceptibility to rust, the X c p reaction remained confined within the rust pustule or spread beyond the pustule area, causing a necrosis of the entire leaf. Prior infection of bean seedlings with bean common mosaic virus (BCMV), NY-15 strain, reduced rust pustule size, but did not affect the reaction to X c p. Screening with X c p and BCMV can be done at the same time during the early vegetative stage, but the interactions of U a with X c p and of BCMV with U a need to be considered in screening for resistance.
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).
The inheritance of specific resistance (SR) and foliar abnormalities (FA) were studied in the F2 and F3 progeny of the following crosses; `PC-50' × Chichara 83-10, `PC-50' × `EZ Pick', A-10-2 × GN `Beryl', and A-10-2 × P114. A single dominant gene controlled SR to rust strain US85NP10-1 in `PC-50' × Chichara 83-10. Duplicate recessive genes determined foliar crippling (FC) in `PC-50' × Chichara 83-10 and A-10-2 × P114. The inheritance of hybrid plant abnormality in `PC-50' × `EZ Pick' and A-10-2 × GN `Beryl' differed from previously reported complementary dominant genes or duplicate recessive genes. Foliar variegation (FV) was controlled by duplicate recessive genes in `PC-50' × Chichara 83-10 and by triplicate recessive genes in `PC-50' × `EZ Pick', A-10-2 × GN `Beryl', and A-10-2 × P114. No associations were detected between SR and FC, SR and FV, or FC and FV.
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.
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.
Common bacterial blight (CBB), rust (RU), and white mold (WM) are serious diseases of great northern (GN) and pinto (P) beans in Nebraska and Colorado. The bacterial diseases halo blight (HB) and brown spot (BS) are sporadic. Severe Fe-induced leaf chlorosis (Fe ILC) occurs on calcareous sites. Separate inoculated disease nurseries are used to screen for resistance to the pathogens causing the above diseases. Yields and seed quality of lines are also determined in non-disease trials. Sources of exotic resistance to the above pathogens and to Fe ILD have been identified and their inheritance determined. A non-structured recurrent selection scheme has mainly been used, occasionally with a backcross program, to combine high levels of the desired traits. Selection for highly heritable traits such as seed size, shape and color, maturity, plant architecture, and RU resistance occurs in early generations while traits of low heritability, such as CBB resistance, WM avoidance, yield, seed coat cracking resistance, and canning quality, are evaluated in separate replicated tests over several years and finally for yield in on-farm-trials. A number of multiple disease resistant, high-yielding, well-adapted GN and P lines are or will be released; P `Chase' (on about 30,000 acres in 1996) and GN WM 3-94-9 (for possible release).
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.
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.
The objective of this cooperative system is to establish reaction of both private and public developed dry beans to common blight, rust, and white mold as well as to document performance in the absence of disease constraints. All commercially available Great Northerns and Pintos plus entries from the Cooperative Dry Bean Nursery and selected entries from public and private breeding programs are included. Entry number ranges from 70 to 80 each year. Annual results are published in “Biological and Cultural Tests for Control of Plant Diseases”.