The role of ethylene in regulating the expression of three lipoxygenase (LOX) genes TomloxA, TomloxB and TomloxC during fruit ripening has been investigated. The study used a combination of low-ethylene fruit containing an ACC oxidase (ACO1) sense-suppressing transgene and tomato fruit ripening mutants deficient in ethylene perception in the case of Never-ripe (Nr) or ripening in the case of the ripening-inhibitor (rin). The results indicate that the three genes are differentially regulated during fruit ripening and that a combination of ethylene and developmental factors influence their expression. The expression of TomloxA declines during ripening and this is delayed in the ACO1 transgenic low-ethylene and Nr fruit indicating that this phenomenon is ethylene regulated. However, transcript abundance also declines during rin fruit development indicating that developmental factors also influence the expression of TomloxA. TomloxB expression increases during fruit ripening and expression is increased by ethylene as reduced accumulation is evident in transgenic and mutant fruit. The same ethylene up-regulated and ripening-related expression is shown by TomloxC, however, expression increases in rin fruit at the onset of colour change, indicating that there may also be a developmental component regulating TomloxC expression. These results indicate that individual LOX isoforms are differentially regulated and may have distinct functions during tomato fruit ripening.

Ethylene production and consumption in Japan

Ethylene and developmental signals regulate expression of lipoxygenase genes during tomato fruit ripening

The effects of ethylene and CO2 on shoot regeneration in excised leaf cultures of Paulownia kawakamii were examined. When both the gases were prevented from accumulating in the headspace of cultures using mercuric perchlorate and potassium hydroxide traps, shoot regeneration frequency improved and callus production was reduced compared to the control and cultures with only one of the gases trapped. Incorporation of either aminoethoxyvinylglycine (AVG) or 1-amino-cyclopropane-1-carboxylic acid (ACC) in the culture medium caused significant reduction in shoot regeneration. There was profuse callus production in the presence of high amounts of ACC, which was accompanied by over sixfold increase in the rate of ethylene production. However, in the presence of AVG callus production was delayed and shoot regeneration decreased, suggesting that low levels of ethylene might be needed for de novo shoot bud induction in Paulownia cultures.

Ethylene production and consumption in Japan

Citations

Ethylene and developmental signals regulate expression of lipoxygenase genes during tomato fruit ripening

Ethylene and CO2 affect direct shoot regeneration from the petiolar ends of Paulownia kawakamii leaves cultured in vitro

References

Ethylene and developmental signals regulate expression of lipoxygenase genes during tomato fruit ripening

Ethylene and CO2 affect direct shoot regeneration from the petiolar ends of Paulownia kawakamii leaves cultured in vitro

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Petrochemical production of Japan