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Breeding for Resistance. Problem origin: late blight of potato in Ireland (1845-46) Phytophthora infestan. Terminology. 1) Parasite 2) Pathogen 3) Disease 4) Resistance 5) Susceptible 6) Hypersensitivity. 7) Tolerance 8) Disease escape 9) Immunity 10) Differential host
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Breeding for Resistance • Problem origin: late blight of potato in Ireland (1845-46) Phytophthora infestan
Terminology 1) Parasite 2) Pathogen 3) Disease 4) Resistance 5) Susceptible 6) Hypersensitivity 7) Tolerance 8) Disease escape 9) Immunity 10) Differential host 11) Physiological race 12) Stability
Genetic Variation in Plant 1) Environmental Variation Gene Action and gene Interaction 1) Gene action: - Dominance - Recessive 2) Gene Interaction: - Complementary action - Modifying action - Inhibiting action - Masking action (epistasis) - Duplicate action - Additive action 2) Heredity Variation: - Quantitative Variation -Qualitative Variation
Genetic Variations in Pathogen • Fungi: 1.1 Obligate parasite 1.2 Facultative parasite Variations: Mutation, genetic recombination 2) Virus: Variations: Mutation, genome recombination 3) Bacteria: 3.1 Gall forming bac. 3.2 soft rot bac. 3.3 Physiological or metabolism altering bac. Variations: binary fission, genetic recombination, mutation
Type and Mechanism of Resistance 1) Base on heredity of resistance 1.1 Monogenic R. 1.2 Oligogenic R. 1.3 Polygenic R. 2) Base on epidemic of disease (Van de Plank) 2.1 Vertical R. 2.2 Horizontal R. 3) Base on mechanism of R. 3.1 Active R. (Responsive R.) 3.2 Passive R. 4) Base on development stage of plant resistance 4.1 Seedling R. 4.2 Adult or mature R. 5) Base on population distribution 5.1 Quantitative R. 5.2 Qualitative R.
Mechanism of Resistance • Immunity • Disease escape • Defense • Resistance • Tolerance
Genetics of Host Plant RelationshipGene for gene concept (Flor, 1956) Genotype of flex and rust Plant genot.: NNPP=R, Disease genot.: a=virulence; A=avirulence
New varieties released (1)New variety characteristics • Novelty or Distinctness • Homogeneity or Uniformity • Stability (New Variety Name “No clear rule”)
Varietal registration • ~30 plants in Thailand are available for Plant Variety Protection (PVP) Certificate • In many countries: USAalmost plants are available for Plant Patent Certificate orPlant Variety Protection (PVP) Certificate
(2) Seed production and multiplication • breeder seed, pre-basic seed or nuclear seed (by breeder and institute) • foundation seed or basic seed (by breeder and institute) • stock seed or registered seed(by grower or government or private sectors) • multiplication seed or certified seed(under the controlled of the seed registered officer)
Varietal released • Government sectors • Private sectors