Plant Genome II Conference
Town & Country Conference Center, San Diego, CA, January, 1994.
PG-II: Genetic Characterization of Tomato Never-ripe (Nr) Associated
Ethylene Insensitivity
Genetic Characterization of Tomato Never-ripe (Nr) Associated
Ethylene Insensitivity.
Hsiao-Ching Yen 1, Sanghyeob Lee 1, Michael Lanahan 2, Harry Klee
2, Steven Tanksley 3 and James Giovannoni 1. 1 Department of
Horticultural Sciences, Texas A&M University, College Station, TX
77843. 2 Monsanto Company, 700 Chesterfield Village Parkway,
Chesterfield, MO 63198. 3 Department of Plant Breeding and
Biometry, Cornell University, Ithaca, NY 14853
The tomato Never-ripe (Nr) allele represents a dominant
mutation which results in only partial ripening of the mature
fruit. We provide evidence suggesting that Nr is a component of
a general ethylene signal transduction pathway regulating the
role of this growth regulator in ripening and additional aspects
of tomato plant development. Partial insensitivity to the triple
response is observed in Nr seedlings germinated in the presence
of either exogenous ethylene or media supplemented with ACC.
Similar observations have been made in the ethylene insensitive
Etr and ein mutants of Arabidopsis thaliana. Preliminary efforts
to determine whether or not Nr is homologous to Etr1 will be
presented. We have also exploited Nr associated ethylene
insensitivity to facilitate genetic mapping as a fist step in a
map-position based gene isolation strategy. Nearly isogenic DNA
pools derived from a subset of an F2 mapping population are being
utilized to isolate linked molecular markers. Progress toward
physiological and genetic characterization of the Nr locus will
be presented.
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