บทคัดย่องานวิจัย

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The Never ripe mutation blocks ethylene perception in tomato.

Lanahan, M. B.; Yen, H. C.; Giovannoni, J. J.; Klee, H. J.;

Plant Cell Year: 1994 Vol: 6 Issue: 4 Pages: 521-530 Ref: 38 ref.

1994

บทคัดย่อ

The Never ripe mutation blocks ethylene perception in tomato.

ABSTRACT :

 

Seedlings of tomato fruit ripening mutants were screened for their ability to respond to ethylene. Ethylene induced the triple response in etiolated hypocotyls of all tomato ripening mutants tested except for one, Never ripe (Nr). This result indicated that the lack of ripening in this mutant is caused by ethylene insensitivity. Segregation analysis indicated that Nr-associated ethylene insensitivity is a single codominant trait and is pleiotropic, blocking senescence and abscission of flowers and the epinastic response of petioles. In normal tomato flowers, petal abscission and senescence occur 4 to 5 days after the flower opens and precede fruit expansion. If fertilization does not occur, pedicel abscission occurs 5 to 8 days after petal senescence. If unfertilized, Nr flowers remained attached to the plant indefinitely, and petals remained viable and turgid more than 4 times longer than their normal counterparts. Fruit development in Nr plants was not preceded by petal senescence; petals and

anthers remained attached until they were physically displaced by the expanding ovary. Analysis of trangenic 1-aminocyclopropane-1-carboxylate (ACC) synthase-overexpressing plants (transformed with the ACC synthase cDNA expressed by the CaMV 35S promoter) indicated that they are phenotypic opposites of Nr plants. Constitutive expression of ACC synthase in tomato plants resulted in high rates of ethylene production by many tissues of the plant and induced petiole epinasty and premature senescence and abscission of flowers, usually before anthesis. There were no obvious effects on senescence in leaves of ACC synthase overexpressers, suggesting that although ethylene may be important, it is not sufficient to cause tomato leaf senescence; other signals are clearly involved.