SI final - Credit Seminar On Self incompatibility its...

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Credit Seminar On Self incompatibility, its molecular basis and uses in crop improvement Presented by: K. Pragnya RAM/11-30 Department of GPBR Chairman: Dr.K.V.Radhakrishna Course incharge: Dr. S. Sudheer Kumar Dr. T. Dayakar Reddy
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Introduction Types of self-incompatibility Molecular mechanism of self-incompatibility Use of self-incompatibility on crop improvement Case studies Conclusion Contents
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Self incompatibility : The prevention of fusion of fertile (functional) male and female gamates after self pollination (Gowers,1998) Koelreuter first report – Verbascum phoeniceum . Term coined by Stout in 1917
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Main Features of SI are: Prevents autogamy and promotes allogamy Maintains high degree of heterozygosity and reduces homozygosity in a species. Results due to morphological, genetic, physiological and biochemical causes. Operate at any stage between pollination and fertilization
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Based on interaction between pollen and pistil SI is classified in to: 1. Complementary system of SI 2. Oppositional system of SI
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Complementary system of SI: Also called as Stimulatory type of SI Pollen and pistil interaction stimulate the growth of pollen grains that differ in SI genotype from that of pistil. Eg: Dendrodium
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Oppositional system of SI: Also called as Inhibitory type of SI Pollen and pistil produce substances which prevent the growth of pollen that has same SI genotype as that of pistil. Germination and growth of pollen differing in SI genotype is not inhibited.
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Classification of Incompatibility systems (Lewis, 1954) Self-incompatibility Heteromorphic Distyly Tristyly Homomorphic Sporophytic Gametophytic
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Self incompatibility is associated with differences in floral morphology . 1. Distyly Two types of styles (short & long) and stamens (low & high) Operates in the family Primulaceae . Primula – two types of flowers – thrum (Ss) & pin (ss) Crosses are compatible between pin x thrum or thrum x pin. Heteromorphic system
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Flowers of Primula veris : thrum flower (left) & pin flower (right)
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Mating Progeny Phenotype Genotyp e Genotype Phenoty pe Pin x Pin ss x ss Incompatible mating - Pin x Thrum ss x Ss 1 ss : Ss 1 Thrum 1 Pin Thrum x Pin Ss x ss 1 Ss : ss 1 Thrum 1 Pin Thrum x Thrum Ss x Ss Incompatible mating -
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2. Tristyly Anthers and style have three positions in the flowers – short, medium and long. Common in the family Lythraceae Genetically controlled by two genes – S & M Compatible mating occurs between long x medium, long x short and medium x short.
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Lythrum salicaria (Lyth aceae) Tristyly
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A) Gametophytic self-incompatibility Discovered by East and Mangelsdorf in 1925 in Nicotiana sanderae . Incompatible reaction of pollen is determined by its own genotype and not by the genotype of the plant on which pollen is produced. Incompatibility is controlled by a single gene S ’ having multiple alleles.
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