X. Good et al., REDUCED ETHYLENE SYNTHESIS BY TRANSGENIC TOMATOES EXPRESSING S-ADENOSYLMETHIONINE HYDROLASE, Plant molecular biology, 26(3), 1994, pp. 781-790
We have utilized a gene from bacteriophage T3 that encodes the enzyme
S-adenosylmethionine hydrolase (SAMase) to generate transgenic tomato
plants that produce fruit with a reduced capacity to synthesize ethyle
ne. S-adenosylmethionine (SAM) is the metabolic precursor of 1-aminocy
clopropane-1-carboxylic acid, the proximal precursor to ethylene. SAMa
se catalyzes the conversion of SAM to methylthioadenosine and homoseri
ne. To restrict the presence of SAMase to ripening fruit, the promoter
from the tomato E8 gene was used to regulate SAMase gene expression.
Transgenic tomato plants containing the 1.1 kb E8 promoter bore fruit
that expressed SAMase during the breaker and orange stage of fruit rip
ening and stopped expression after the fruit fully ripened. Plants con
taining the 2.3 kb E8 promoter expressed SAMase at higher levels durin
g the post-breaker phases of fruit ripening and had a substantially re
duced capacity to synthesize ethylene.