Plant Genome II Conference
Town & Country Conference Center, San Diego, CA, January, 1994.
PG-II: S-RELATED SEQUENCES ARE NOT SUFFICIENT TO PRODUCE
SELF-INCOMPATIBILITY IN LYCOPERSICON ESCULENTUM
S-RELATED SEQUENCES ARE NOT SUFFICIENT TO PRODUCE
SELF-INCOMPATIBILITY IN LYCOPERSICON ESCULENTUM
Robert Bernatzky, Richard H. Glaven and Bruce A. Rivers
Department of Plant and Soil Sciences, University of
Massachusetts, Amherst, MA 01003.
Stylar proteins involved in the self-incompatible (SI)
response of L. hirsutum have been identified and mapped to the
locus that controls Si (S-locus). L esculentum, self-compatible
(SC) cultivated tomato, does not display these proteins. Hybrids
between SC L. esculentum and SI L. hirsutum are self-sterile
despite these individuals bearing pollen containing the S-allele
of L. esculentum. In progeny derived from backcrossing the
hybrids to L csculentum, there was strong correlation between the
presence of the S-allele from L. hirsutum and self-infertility.
However, this relationship was uncoupled in a number of backcross
(BC) progeny. The SI response appeared to be non-existent in two
self-fertile BC individuals that were heterozygous for the
S-allele of L. hirsutum, based on Mendelian segregation of a
tightly linked DNA marker, CDIS, in selfed progeny. Self-fertile
individuals in these progeny that were homozygous for the
L.hirsutum allele of the linked marker were also determined to be
homozygous for the S-related proteins of L. hirsutum through
testcrosses with L. esculentum. In other words, plants were
produced that were homozygous for a functional S-allele, but were
self-fertile. To further clarify the role the S-locus and
flanking chromosome regions play in SI, the S-locus was finely
mapped relative to 14 chromosome I RFLP markers covering a
distance of approximately 53 cM. These markers are being used to
introgress varying lengths of chromosome I segments from L.
hirsutum into L. esculentum and from L. esculentum into L.
hirsuruni. The SI response of the different partial substitution
lines is being investigated.
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