1910s Timeline - John Innes Centre

1930s Chemical nature of
nucleic acid investigated
Nucleic acid was thought to be a
tetranucleotide composed of
one unit each of adenylic,
guanylic, thymidylic and
cytidylic acids. The ubiquitous
presence of nucleic acid in the
chromosome was generally
explained in purely physiological
terms
1930s-40s M B Crane, D Lewis
and associates elucidate the
genetically controlled
incompatibility mechanism in
plants and its practical
application to economic crops
During the 1930s the study of
pollen incompatibility and
sterility which has been going
on for some years is extended
from cherries, plums and apples
to pears. Cytological
examination of the varieties
available begins. Morley
Benjamin Crane’s pollination
experiments (assisted by W J C
Lawrence in the 1920s and A. G
Brown from 1935) have allowed
fruit trees to be grouped
according to whether they are
self-fertile (set fruit with their
own pollen) or whether they
require cross-pollination with
another variety. By the end of
the 1930s about a million
pollinations have been made at
JIHI to test the success of
crosses that can happen in the
orchard, and Crane is able to
publish practical rules on which
of the main varieties should be
planted together to give good
crops of fruit and which should
not; his advice is regularly
sought by fruit growers.
Despite their practical value,
these findings in themselves
offer no real insight into the
genetic mechanisms
determining incompatibility
relations. The hypothesis that
incompatibility relations are
determined by a series of allelic
genes, denoted by S 1 , S 2 , S 3 …,
was formulated by E. M. East
and A. J. Mangelsdorf in 1925,
but it had not been possible to
apply this insight to explain the
more complicated cases of
incompatibility relations in fruit.
The first clue came from the
young C. D. Darlington’s
chromosome counts in a
number of Prunus species in the
mid-1920s which established
that sweet cherries were diploid,
sour cherries tetraploid and the
plums hexaploid. These findings
helped to explain some of the
complexity in the relationships
between pollen and style.
Further advances are made by
Dan Lewis (Assistant
Pomologist) from 1940 using
the more amenable species
Oenothera organensis as a
model plant. By inducing
tetraploidy in this plant Lewis is
able to analyse the relations of
pairs of S alleles in detail. Lewis
also develops techniques for
studying pollen-tube growth in
Oenothera which he is later able
to apply to physiological studies
of incompatibility in fruit.
Audio-clip from Brian
Harrison’s interview
with Dan Lewis in
which he talks about
his work on incompatibility
relations
See also:
The Fertility Rules in Fruit
Planting. John Innes Leaflet No.
4., London: JIHI, 1940. On p. 2,
Crane estimated that the total
fruit crop of the country could
be increased 10-20 per cent in
value by correct inter-planting.
K Mather and W J C Lawrence,
‘Morley Benjamin Crane, 17
March 1890- 17 September
1983’, Biographical Memoirs of
Fellows of the Royal Society, 31
(1985): 89-110.
Page 18 of 91