Scientia Horticulturae 216 (2017) 22–28 Contents lists available at ScienceDirect Scientia Horticulturae journal homepage: www.elsevier.com/locate/scihorti Expression analysis by RT-PCR of genes involved in ethylene synthesis and signal transduction in miniature roses Mohammad Al-Salem, Margrethe Serek ∗ Leibniz University of Hannover, Faculty of Natural Sciences, Institute of Horticulture Production Systems, Floriculture, Herrenhaeuser Str. 2, D-30419 Hanover, Germany a r t i c l e i n f o Article history: Received 30 September 2016 Received in revised form 27 December 2016 Accepted 29 December 2016 Keywords: Ethylene receptor Ethylene sensitivity Gene expression Postharvest Rosa hybrida L. Signal transduction a b s t r a c t 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. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Miniature rose, Rosa hybrida L., is one of the most economi- cally important ornamental plants for indoor use. Miniature potted roses have become very popular in the last two decades due to their availability in a wide range of colors, sizes, growth habits, and to improved postharvest performance. The annual world produc- tion is estimated to be more than 100 million plants, and Denmark is the largest producer with nearly 50% of the world’s production (Pemberton et al., 2003). The number of miniature rose plants sold in 2015 at Flora Holland, the world largest flower auction, reached 47 million, generating revenues of EUR 57 million (FloraHolland, 2016). Ethylene is one of the most important factors affecting the qual- ity, appearance and longevity of many ornamentals (Serek et al., 2006; Ferrante et al., 2015). In miniature roses, ethylene can cause unwanted effects such as premature and accelerated wilting and ∗ Corresponding author. E-mail address: serek@zier.uni-hannover.de (M. Serek). abscission of leaves, floral buds, petals and flowers, as well as leaf yellowing or discoloration (Serek 1993; Andersen et al., 2004). The display life of some commercially grown miniature potted rose cul- tivars was compared by Müller et al. (1998), and it was found that it varied considerably, at least partly due to differences in endogenous ethylene production and sensitivity to exogenous ethylene. In higher plants, the mechanism of ethylene biosynthesis has been well investigated (Yang and Hoffman, 1984; Xu and Zhang 2015). Ethylene signal transduction has also been investigated extensively, resulting in a model encompassing the following well- established aspects (Merchante et al., 2013; Cho and Yoo 2015; Gallie 2015; Shakeel et al., 2015). In the absence of ethylene, the ethylene receptors, located in the ER membrane, activate CTR1 (and its homologs) which is associated with the receptors and, when activated, phosphorylates and inhibits EIN2 (a membrane protein also located in the ER membrane). In the presence of ethy- lene, CTR1 is “switched off”, and EIN2 becomes dephosphorylated, leading to release of its C-terminal domain (Ju et al., 2012). This domain translocates to the nucleus, where it blocks degradation of the transcription factors EIN3/EIL1 and thus activates the transcrip- tional response to ethylene. Other, less well-characterized proteins, http://dx.doi.org/10.1016/j.scienta.2016.12.029 0304-4238/© 2016 Elsevier B.V. All rights reserved.