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Ss  ss -> Ss and ss in a 1:1 ratio PowerPoint Presentation
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Ss  ss -> Ss and ss in a 1:1 ratio

Ss  ss -> Ss and ss in a 1:1 ratio

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Ss  ss -> Ss and ss in a 1:1 ratio

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  1. Heterostyly is controlled by a gene S with simple inheritance: Ss yields a short-styled flower. ss yields a long-styled flower. Ss  ss -> Ss and ss in a 1:1 ratio S s s Ss ss ss s Ss

  2. Heterostyly is controlled by a gene S with simple inheritance: Ss (short-styled) flower  ss (long-styled) flower. thrum x thrum gives 3:1 thrum:pin, ie. Ss X Sx = SS, Sx, Sx, ss pin X pin gives all pin i.e. ss X ss = ss Ss  ss -> Ss and ss in a 1:1 ratio S s s Ss ss ss s Ss

  3. Two kinds of self-incompatibility: Gametophytic: S1S2 femaleS1S3 male yields inhibition of S1 pollen, not of S3 pollen --- happens on the stigma Sporophytic: No S1S2 S1S3 yields inhibition of pollen Only the same two alleles yield inhibition --- happens in the style

  4. Introduce papillae and pollen size

  5. The Primula supergene G - style length - short-style flowers have large pollen grains and and small stigmatic papillae - long-style flowers have small pollen grains and large stigmatic papillae So big pollen grains land on long styles where there are big stigmatic papillae. Little pollen grains land on short styles where there are small stigmatic papillae The self incompatibility is sporophytic. Sp - stigma papilla length I - self incompatibility P - pollen grain size A - anther height

  6. aob.oupjournals.org/cgi/reprint/78/6/759.pdf

  7. Self-incompatibility: Antibody-antigen response: protein found in styles of petunias with incompatible pollen tubes, not with compatible tubes - mutations indicate two subgenes with different actions, one the pollen reaction and one the style reaction - tetraploids between incompat diploids fail (as long as different alleles are present the antigen-antibody response proceeds. multiple alleles are found in species to allow a diverse definition of self (45 alleles in 500 oenothera organensis plants, at least 75 in T, repens and 150 in T. pratense ) --- Grant 1975