Molecular Cloning and Characterization of Four Genes Encoding Ethylene Receptors Associated with Pineapple (Ananas comosus L.) Flowering

Abstract

Exogenous ethylene, or ethephon, has been widely used to induce pineapple flowering, but the molecular mechanism behind ethephon induction is still unclear. In this study, we cloned four genes encoding ethylene receptors (designated AcERS1a, AcERS1b, AcETR2a, and AcETR2b). The 5′ flanking sequences of these four genes were also cloned by self-formed adaptor PCR and SiteFinding-PCR, and a group of putative cis-acting elements was identified. Phylogenetic tree analysis indicated that AcERS1a, AcERS1b, AcETR2a, and AcETR2b belonged to the plant ERS1s and ETR2/EIN4-like groups. Quantitative real-time PCR showed that AcETR2a and AcETR2b (subfamily 2) were more sensitive to ethylene treatment compared with AcERS1a and AcERS1b (subfamily 1). The relative expression of AcERS1b, AcETR2a, and AcETR2b was significantly increased during the earlier period of pineapple inflorescence formation, especially at 1–9 days after ethylene treatment (DAET), whereas AcERS1a expression changed less than these three genes. In situ hybridization results showed that bract primordia (BP) and flower primordia (FP) appeared at 9 and 21 DAET, respectively, and flowers were formed at 37 DAET. AcERS1a, AcERS1b, AcETR2a, and AcETR2b were mainly expressed in the shoot apex at 1–4 DAET; thereafter, with the appearance of BP and FP, higher expression of these genes was found in these new structures. Finally, at 37 DAET, the expression of these genes was mainly focused in the flower but was also low in other structures. These findings indicate that these four ethylene receptor genes, especially AcERS1b, AcETR2a, and AcETR2b, play important roles during pineapple flowering induced by exogenous ethephon.

Ethylene Role in Plant Growth, Development and Senescence: Interaction with Other Phytohormones

“…In China rose HrsETR and HrsERS transcript levels were differentially expressed in the bud flower stage in style-stigma plus stamen, petals and ovary with different temporal patterns suggesting a possible tissue-specific role (Trivellini et al, 2011a). In pineapple, the expression of the ethylene receptors AcERS1a , AcERS1b , AcETR2a , and AcETR2b was higher in bract primordia and flower primordia ethephon-treated (Li et al, 2016), suggesting an important role during inflorescence development because ethylene induces pineapple flowering. In Arabidopsis , ETR2 receptor was developmentally regulated in the inflorescence, floral meristems, and developing petals and ovules (Sakai et al, 1998).…”

The Role of 1‐Methylcyclopropene in the regulation of ethylene biosynthesis and ethylene receptor gene expression in Mangifera indica L. (Mango Fruit)

“…Ethylene receptors are initial factors participating in the ethylene signal transduction pathway (Shakeel et al, ). They are participated in numerous biological processes, negatively regulating the ethylene response and inhibiting responses under the insufficiency of ethylene with the N‐terminal domain regulating the receptor signaling condition (Li et al, ; Merchante, Alonso, & Stepanova, ; Shakeel et al, ). Ethylene receptor genes have been identified in many plant species, and their expression patterns have been examined (Rasori et al, ).…”

Comparative Analyses of the Transcriptome and Proteome of Comte de Paris and Smooth Cayenne to Improve the Understanding of Ethephon-Induced Floral Transition in Pineapple

“…A higher concentration of ethephon might be perceived as one type of stress encountered by pineapple plants, which results in the increased expression of TFs after ethephon treatment [17][18]. In addition to the previously mentioned ERFs, other TFs, including MYBs, WRKYs, NACs and bHLHs, were shown to be upregulated in response to ethephon treatment.…”

“…The DEP analysis also revealed that there was a difference between CP and SC with respect to ACO protein expression before ethephon induction treatment. ETR is a negative regulator of the ethylene signal transduction pathway, that is, it inhibits the pathway when it is not bound to ethylene [17]. Reductions in ETR and ERF levels increase the sensitivity of plants to ethylene, and a lower concentration of ethylene could stimulate the ethylene response and induce pineapple flowering [36][37].…”