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Commercial-scale Alternaria brown spot resistance screening as the first step in breeding new mandarins for Australia

Miles, A. K. and Newman, T. K. and Gultzow, D. L. and Parfitt, S. C. and Drenth, A. and Smith, M. W. (2015) Commercial-scale Alternaria brown spot resistance screening as the first step in breeding new mandarins for Australia. Acta Horticulturae, 1065 . pp. 971-978. ISSN 0567-7572

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Article Link(s): http://www.actahort.org/books/1065/1065_121.htm

Abstract

Rapid screening tests and an appreciation of the simple genetic control of Alternaria brown spot (ABS) susceptibility have existed for many years, and yet the application of this knowledge to commercial-scale breeding programs has been limited. Detached leaf assays were first demonstrated more than 40 years ago and reliable data suggesting a single gene determining susceptibility has been emerging for at least 20 years. However it is only recently that the requirement for genetic resistance in new hybrids has become a priority, following increased disease prevalence in Australian mandarin production areas previously considered too dry for the pathogen. Almost all of the high-fruit-quality parents developed so far by the Queensland-based breeding program are susceptible to ABS necessitating the screening of their progeny to avoid commercialisation of susceptible hybrids. This is done effectively and efficiently by spraying 3-6 month old hybrid seedlings with a spore suspension derived from a toxin-producing field isolate of Alternaria alternate, then incubating these seedlings in a cool room at 25°C and high humidity for 5 days. Susceptible seedlings show clear disease symptoms and are discarded. Analysis of observed and expected segregation ratios loosely support the hypothesis for a single dominant gene for susceptibility, but do not rule out the possibility of alternative genetic models. After implementing the routine screening for ABS resistance for three seasons we now have more than 20,000 hybrids growing in field progeny blocks that have been screened for resistance to the ABS disease.

Item Type:Article
Business groups:Horticulture and Forestry Science
Additional Information:Journal article; Conference paper XII International Citrus Congress - International Society of Citriculture, Valencia, Spain. Drenth, Andre/A-4915-2008
Keywords:FF003Horticultural Crops (NEW March 2000) FF020Plant Breeding and Genetics FF610Viral, Bacterial and Fungal Diseases of Plants (NEW March 2000) HH600Host Resistance and Immunity QQ050Crop Produce QQ500Food Composition and Quality breeding programmes crop quality disease resistance fruits fungal diseases genes genetic control hybrids leaves mandarins new cultivars plant diseases plant pathogenic fungi plant pathogens progeny seedlings susceptibility wild relatives Australia Queensland Alternaria alternata Citrus Citrus reticulata fungi Alternaria Pleosporaceae Pleosporales Dothideomycetes Pezizomycotina Ascomycota fungi fungus eukaryotes APEC countries Australasia Oceania Commonwealth of Nations Developed Countries OECD Countries Citrus Rutaceae Sapindales dicotyledons angiosperms Spermatophyta plants Australia
Subjects:Science > Botany > Genetics
Plant culture > Fruit and fruit culture
Plant pests and diseases
Deposited On:13 Jul 2015 02:06
Last Modified:13 Jul 2015 02:06

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