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An inbred backcross (IBC) population derived from Lycopersicon hirsutum LA407 and L. esculentum was evaluated in replicated field trials to assess its potential for the improvement of red-fruited tomatoes. Significant phenotypic variation among genotypes was detected for the hue (tint), L (darkness), and chroma (saturation) of color. Significant effects due to environment and genotype × environment interactions also were observed. One superior inbred backcross line from this population, IBL 2349, was used to develop an F2 population and to explore the genetic basis of color. Two independent L. esculentum quantitative trait loci (QTL) associated with improved color were identified based on linkage to markers mapping to chromosome 4 and chromosome 11. Epistatic interactions were identified between the two L. esculentum loci. Unexpected epistatic interactions also were identified between L. esculentum loci and an LA407 introgression on chromosome 7 present within IBL 2349. The two L. esculentum QTL and the epistatic interactions were confirmed in replicated trials with F3 and F4 families. The loci identified in this study and their epistatic interactions may provide additional tools for the improvement of red-fruited tomatoes in breeding programs.

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), the genetic base of Beit Alpha cucumber germplasm should be diversified to maximize its use in plant improvement. The inbred backcross breeding method ( Wehrhahn and Allard, 1965 ) has been useful for broadening the genetic base of cucumber and

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genetic diversity, but also by the lack of appropriate genetic stocks for rapid genetic mapping of economically important traits and the inability to carry on strategic assessments of epistatic interactions. The inbred backcross breeding method ( Wehrhahn

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Abstract

Selected inbred backcross lines from 2 cucumber (Cucumis sativus L.) populations were studied to determine whether genetic variation existed within and between 2 populations for fruit length and weight. F1 hybrids from intra-population diallel and inter-population North Carolina Design II matings were evaluated in 1981 under greenhouse or field conditions. Significant genetic variability was found among selected inbred backcross lines within each population for fruit length and weight. General (GCA) and specific (SCA) combining ability estimates were significant, indicating that both additive and nonadditive effects were important for trait expression among lines from the same population. Analysis of inter-population design II F1 hybrids indicated that male and female (GCA) or additive effects accounted for most of the variation between lines for fruit length and weight. Significance of specific combinations (SCA) and the F2 data confirmed that genetic variation existed between populations. Therefore, selection and intercrossing of specific inbred backcross lines from both populations may lead to maximum fruit size and recovery of the desired horticultural characterisics of the recurrent parent. The inbred backcross line method is well suited for the transfer of genes controlling a quantitative trait from an unadapted or exotic source into a commercially acceptable type.

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Abstract

Four populations of inbred backcross lines of common bean (Phaseolus vulgaris L.), developed from crosses between ‘Sanilac’, the recurrent parent, and 4 donor parents (‘BBL 240’, 15R-148, ‘Swedish Brown’, and PI 229815), were analyzed for total seed protein percentage. In each population a substantial number of lines having significantly higher protein levels than ‘Sanilac’ were recovered. The basis for enhanced protein percentage was attributed to increased amounts (g/seed) of phaseolin and nonphaseolin protein, either singularly or together, and either with or without a decrease in the nonprotein seed fraction. Lines from different populations were characterized by different combinations of altered levels of the various seed fractions. Although seed size varied depending on the seed fractions present, no obviously shriveled seeds were observed. Lines having enhanced protein and seed yields comparable to or greater than the recurrent parent, ‘Sanilac’ were recovered.

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The inbred backcross (IBC) breeding method is being used to introgress genes controlling high fruit soluble solids from a wild tomato species (Lycopersicon cheesmanii f. minor) into a California processing tomato cultivar (Lycopersicon esculentum cv. UC204B). One IBC tomato population (i.e. P1: 106 lines) is being used to map quantitative trail loci (QTL) for soluble solids and other traits. A genetically related but independently generated IBC population (i.e. P2: 96 lines) is being used to lest the efficiency of QTL-linked RPLPs for indirect marker-assisted selection (MAS) to improve soluble solids. P1 was analyzed for fruit quality traits in a replicated field design over 2 years. Twelve P1 lines were significantly greater than UC204B for soluble solids and also had acceptable fruit weights and horticultural traits. All twelve lines have been publicly released for further breeding efforts. In P1. we have identified RPLP markers that have significant correlations to QTL. Some of these markers map to regions previously reported by other researchers to contain QTL for the same traits. We will use 70-80 markers spaced approximately 10-20 cM apart across the genome to screen PI and map QTL. The RPLP analyses are currently in progress. P2 was replicated for one year using the same field design as P1. and analyzed for the same traits. P2 will be screened with QTL-linked RFLPs identified in P1 to test the consistency of QTL locations between independently derived populations. P2 lines selected using RFLP data will be compared to P2 lines identified by classical selection indices. This will indicate if MAS for QTL is effective in a population (P2) genetically independent from the mapping population (P1).

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.-derived U.S. processing market-type inbred backcross lines (IBL) were released in Jan. 2011 by the Agricultural Research Service, U.S. Department of Agriculture to provide genetic stocks for broadening the genetic base of pickling cucumber. The IBL were

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Abstract

The inbred backcross line method was used to analyze the inheritance of fruit length and weight in cucumber (Cucumis sativus L.). Two populations were produced by crossing a small-fruited, adapted breeding line as the recurrent parent with 2 unadapted and large-fruited lines as donor parents. Marker genes were used in both populations to test for Mendelian expectations. Segregation was normal for all markers in both populations. Nevertheless, significant deviations from binomial expectations occurred, indicating that there were difficulties in estimating gene number and genetic variance without bias. Heritability was moderately high for fruit length and intermediate for fruit weight in both populations. No major genes controlling fruit length or weight were detected using the inbred backcross line method, and only estimates of minimum gene number were obtained. Inbred backcross lines having fruit weight equal to or greater than the large-fruited donor parent were recovered in both populations. However, in neither population were lines recovered with fruit as long as those of the donor parent.

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inbred backcross (IBL; BC 2 S 3–5 ) chilling-tolerant U.S. processing lines possessing acceptable yield and quality traits are being released by the Agricultural Research Service (ARS), U.S. Department of Agriculture (USDA). The chilling tolerance of

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In an effort to reduce chemical usage to prolong postharvest keeping time of cut flowers, a cross was made between a long-lived (vase life, 10.9 days) inbred line of Antirrhinum majus and a short-lived (vase life, 5.0 days) inbred line. The F1 hybrid was backcrossed to the short-lived parent. Sixty plants of the BC1 generation were carried on through three generations of selfing by single-seed descent. Eight replications each of 60 BC1S3 families, the parents, and the F1 hybrid were grown in the greenhouse, harvested with 40-cm stems when five florets opened, and placed in distilled water for vase life evaluation. Stems were discarded when 50% of the florets on a spike wilted, browned, or dried. Three families proved not significantly different from the long-lived inbred parent. Results indicate that inbred backcross breeding shows potential to increase the postharvest keeping time of short-lived Antirrhinum majus inbred lines.

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