A natural frameshift mutation in Campanula EIL2 correlates with ethylene insensitivity in flowers

Abstract

BackgroundThe phytohormone ethylene plays a central role in development and senescence of climacteric flowers. In ornamental plant production, ethylene sensitive plants are usually protected against negative effects of ethylene by application of chemical inhibitors. In Campanula, flowers are sensitive to even minute concentrations of ethylene.ResultsMonitoring flower longevity in three Campanula species revealed C. portenschlagiana (Cp) as ethylene sensitive, C. formanekiana (Cf) with intermediate sensitivity and C. medium (Cm) as ethylene insensitive. We identified key elements in ethylene signal transduction, specifically in Ethylene Response Sensor 2 (ERS2), Constitutive Triple Response 1 (CTR1) and Ethylene Insensitive 3- Like 1 and 2 (EIL1 and EIL2) homologous. Transcripts of ERS2, CTR1 and EIL1 were constitutively expressed in all species both throughout flower development and in response to ethylene. In contrast, EIL2 was found only in Cf and Cm. We identified a natural mutation in Cmeil2 causing a frameshift which resulted in difference in expression levels of EIL2, with more than 100-fold change between Cf and Cm in young flowers.ConclusionsThis study shows that the naturally occurring 7 bp frameshift discovered in Cmeil2, a key gene in the ethylene signaling pathway, correlates with ethylene insensitivity in flowers. We suggest that transfer of the eil2 mutation to other plant species will provide a novel tool to engineer ethylene insensitive flowers.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0786-4) contains supplementary material, which is available to authorized users.

Light Deficiency Inhibits Growth by Affecting Photosynthesis Efficiency as well as JA and Ethylene Signaling in Endangered Plant Magnolia sinostellata

“…Phytohormones are essential for coordinating various signaling pathways in response to abiotic stress in plants [43]. In addition to the stress response and plant growth, phytohormones can also regulate leaf abscission [93,94], which were observed in M. sinostellata in this study (Figure 1A). The increase in ethylene content can promote leaf abscission [95,96].…”

CRISPR/Cas9‐mediated mutation of Eil1 transcription factor genes affects exogenous ethylene tolerance and early flower senescence in Campanula portenschlagiana

“…Partial CDS for Eil1a ( CpEil1a _allele1, OM925995; CpEil1a _allele2, OM925996; both 2262 bp) and Eil1b ( CpEil1b _allele1, OM925997; CpEil1b _allele2, OM925998; both 924 bp) from C. portenschlagiana ‘PKMp11’ were cloned. This added 1668 and 333 bp, respectively, to the previously published Eil1a (KX058425.1; 594 bp) and Eil1b (KX058426.1; 591 bp) gene fragments (Jensen et al ., 2016 ). Single nucleotide polymorphisms (SNPs) found between the two alleles in each CpEil1 gene enabled us to assign the CRISPR/Cas9‐induced mutations to specific alleles (Figure S1 ).…”

“…Wang et al, 2013). In Campanula medium, a naturally induced 7-bp deletion in the ORF of Eil2, isolated from flowers, correlated with flowers insensitive to exogenously applied ethylene (Jensen et al, 2016). The potential of downregulating expression of specific EIN3/Eil genes to obtain ethylene insensitive flowers by using genetic modifications is further strengthened by a paper showing that VIGS-mediated silencing in two petunia Eils, PhEil1 and PhEil2, delayed flower senescence (Liu et al, 2016).…”

“…Studies in carnation, peony, petunia and rose have shown that up‐regulation of expression levels of specific EIN3/Eil gene(s) in the flowers is correlated with sensitivity to exogenous ethylene (Iordachescu and Verlinden, 2005 ; Liu et al ., 2016 ; Singh et al ., 2019 ; Wang et al ., 2013 ). In Campanula medium , a naturally induced 7‐bp deletion in the ORF of Eil2 , isolated from flowers, correlated with flowers insensitive to exogenously applied ethylene (Jensen et al ., 2016 ). The potential of down‐regulating expression of specific EIN3/Eil genes to obtain ethylene insensitive flowers by using genetic modifications is further strengthened by a paper showing that VIGS‐mediated silencing in two petunia Eils , PhEil1 and PhEil2 , delayed flower senescence (Liu et al ., 2016 ).…”

Rapeseed as an Ornamental

“…Similarly, in petunia, silencing of PhFBH4 (a basic helix-loop-helix transcription factor) using virus-induced gene silencing or an antisense approach prolonged flower longevity by modulating the ethylene biosynthesis pathway [28]. Also, in Campanula, a naturally occurring 7 bp frameshift of a key ethylene insensitive homologous gene (Cmeil2) in the ethylene signaling pathway may be used to screen for flower longevity [29]. Similarly, transgenic Torenia plants incorporating a fragment of a 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase gene had a two day extension of flower longevity [30].…”