Ss ss Ss and ss in a 1:1 ratio

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 -gt Ss and ss in a 11 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 31 thrumpin, ie. Ss X Sx
SS, Sx, Sx, ss pin X pin gives all pin i.e. ss X
ss ss
Ss ? ss -gt Ss and ss in a 11 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
(No Transcript)
6
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
7
aob.oupjournals.org/cgi/reprint/78/6/759.pdf
8
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