Expression analysis by RT-PCR of genes involved in ethylene synthesis and signal transduction in miniature roses

- Miniature roses with different ethylene sensitivity were investigated.
- Transcription of genes for ethylene signaling and biosynthesis was determined.
- No correlation between expression patterns and ethylene sensitivity was found.
- The tested genes do not appear to be a key in determining ethylene sensitivity.

Ethylene is one of many factors that affect the quality, appearance and longevity of miniature roses. In this study RT-PCR is used to compare the expression of ethylene biosynthetic genes and ethylene signal transduction genes at different stages of flower development in the two cultivars 'Vanilla' and 'Lavender', which show low and high ethylene-sensitivity, respectively, and their F1 offspring. The genes for the ethylene receptors RhETR1, RhETR2 and RhETR3, the genes for the receptor-associated signaling proteins RhCTR1 and RhCTR2, the genes for the transcription factors RhEIN3 and RhEIL, and the genes for the ACC synthases RhACS1 and RhACS2 each had an expression pattern that varied between the tested plants and tissues, but could not be correlated with the ethylene sensitivity of the plants. RhETR1, RhETR2, RhETR3 and RhEIN3 were, e.g., expressed more in 'Vanilla' than in 'Lavender' in most, but not all, of the investigated tissues, but were in general not expressed more in progeny with low sensitivity than in progeny with high sensitivity. No expression was detected for the 4 other genes that were investigated, i.e. genes for RhETR4, RhACS3, RhACS4 and RhACS5. It is concluded that the precise transcriptional activities of the tested genes do not appear to be crucial in determining the ethylene sensitivity of miniature roses. It therefore appears likely that transcription of other genes involved in ethylene signal transduction, posttranscriptional or posttranslational control, or crosstalk with other signal transduction pathways may be important for the degree of ethylene sensitivity of miniature roses.