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  • Author or Editor: John R. Stommel x
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The carotenoids have an important influence on tomato fruit quality and enhance the fruit contribution to human nutrition. Expression of the high pigment (hp) locus in tomato results in increased total carotenoids and increased efficiency of utilization of the polyenes. A similar mutant, dark green (dg), contains higher level of chlorophyll in immature fruit and results in darker red pigmentation, both externally and internally in ripe fruit. Random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) analyses were performed using two pairs of near isogenic lines (NILs) designed to be isogenic at the hp and dg loci. Sixty-four AFLP primer pairs and more than 1000 RAPD 10-mer primers were screened for polymorphism between each pair of the NILs. One RAPD marker was identified to be linked to the hp gene, and two AFLP primer pairs showed polymorphic fragments which distinguished the dg NILs. The markers identified in this study will be converted to allele specific SCAR (sequence characterized amplified region) markers, which are more useful in marker-assisted selection breeding programs.

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Anthracnose, caused by Colletotrichum coccodes, is a serious ripe tomato fruit rot disease. Genetic resistance to anthracnose is not available in commercial tomato cultivars, but has been reported in small-fruited Plant Introductions (P.I.), and with lesser intensity in a number of breeding lines. Transfer of high levels of resistance from these breeding lines or P.I.s to elite materials has proven difficult. Inheritance of resistance has been described as complex with at least six loci influencing resistance reactions. Segregating populations originating from a cross between a susceptible tomato breeding line and a large-fruited breeding line (88B147) with resistance derived from Lycopersicon esculentum var. cerasiforme P.I. 272636, were evaluated for anthracnose resistance. Analysis of anthracnose resistance in puncture-inoculated fruit indicated small, but significant, additive genetic effects for resistance. Additional populations were developed from crosses of a susceptible inbred processing tomato cultivar with: 1) the resistant P.I. 272636, 2) an unadapted small-fruited resistant line developed from P.I. 272636, and 3) the large-fruited breeding line 88B147, also with resistance derived from P.I. 272636. Small additive effects identified in large-fruited material, in comparison to the resistant P.I., suggests that resistance loci have been lost during germplasm development. This is consistent with the relatively larger lesions observed in large-fruited lines derived from P.I. 272636. Positive correlations were noted between small fruit size and high levels of anthracnose resistance. Identification of molecular markers linked to resistance genes in the respective populations will be discussed.

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Considerable diversity exists in Capsicum L. germplasm for fruit and leaf shape, size and color, as well as plant habit. This morphological diversity, together with diverse ripe fruit color and varying hues of green to purple and variegated foliar pigmentation, affords myriad opportunities to develop unique cultivars for ornamental applications. The Agricultural Research Service of the United States Department of Agriculture announces the release of a new pepper [Capsicumannuum (L.)] cultivar named `Black Pearl'. `Black Pearl' is intended for ornamental applications and affords growers a new crop to add to their bedding and landscape plant assortment. `Black Pearl' combines black foliage with erect clusters of small round red-pigmented fruit. The vibrant fruit and foliage colors of this new cultivar add interest to the summer and fall garden. Black Pearl' has been trialed extensively for use as a bedding plant where its compact growth habit, black foliage, and brightly colored fruit provide an attractive ornamental display. Limited evaluations suggest that this cultivar is equally well suited for pot culture under high light conditions. `Black Pearl' was designated a 2006 All America Selection award winner after completion of national trials in 2004. `Black Pearl' is a release made available from a cooperative research and development agreement with Pan American Seed Company. Seed of `Black Pearl' is available from Pan American Seed Company, 622 Town Road, West Chicago, IL 60185. Plant Variety Protection for `Black Pearl' is pending.

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Ornamental peppers are a novel and growing segment of the ornamentals industry. Currently available varieties are utilized as pot plants and in bedding plant applications. Utilizing unimproved populations developed from initial crosses with Indian Capsicum land races, germplasm lines with unique gene combinations for multiple fruiting, fruit orientation, leaf pigmentation and leaf variegation were developed and released by USDA-ARS. Via introgression of diverse Capsicum species accessions and heirloom varieties into these populations, more recent efforts seek to exploit abundant genetic variation for fruit shape, size, color and pungency, foliar attributes, and plant growth habit to develop new pepper germplasm for ornamental and dual ornamental/culinary applications. Fruit pungency of selected material may range from mild to extremely pungent. Fruit shape may be round, conical, or lobed. Whereas small fruit size is generally well suited for ornamental applications, ornamental/culinary types exploit larger upright conical or small bell-shaped fruit. Plant foliage may be uniformly green in color, exhibit varying degrees of anthocyanin accumulation, or display variegation. Inheritance of selected attributes, potential barriers to development of select recombinants, and examples of representative advanced selections in the breeding program will be presented.

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Considerable diversity exists in Capsicum L. germplasm for fruit and leaf shape, size, and color as well as plant habit. Using F1, F2, and backcross generations developed from diverse parental stocks, this report describes the inheritance patterns and relationships between unique foliar characters and diverse fruit and plant habit attributes. Our results demonstrate that pepper fruit color, shape, and fruit per cluster were simply inherited with modifying gene action. Broad-sense heritability for fruit color and shape and fruit per cluster was high, whereas narrow-sense heritability for these characters was moderate to low. Although fruit clustering was simply inherited, the number of fruit per cluster exhibited a quantitative mode of inheritance. High fruit counts per cluster were linked with red fruit color and anthocyanin pigmented foliage. Fruit shape was linked with immature fruit color and inherited independently of mature fruit color. Leaf color, length, and plant height were quantitatively inherited. Leaf shape did not vary, but leaf length varied and was positively correlated with leaf width. Broad-sense heritability for leaf characters, including leaf length, leaf width, and leaf color, was high. With the exception of leaf width, which exhibited low narrow-sense heritability, high narrow-sense heritability for leaf characters denoted additive gene action. Plant height displayed high broad-sense heritability. Moderate narrow-sense heritability suggested that additive effects also influence plant height. Analysis of segregating populations demonstrated that red and orange fruit color can be combined with all possible leaf colors from green to black. These results provide new data to clarify and extend available information on the inheritance of Capsicum fruit attributes and provide new information on the genetic control of leaf characters and plant habit.

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