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Abstract Background This study aimed to produce Odontoglossum ringspot virus (ORSV)-free Cymbidium orchid ‘New True’ plants from ORSV-infected mother plants by culturing their meristems and successively repeating subcultures of protocorm-like bodies (PLBs) derived from the meristems. Results Initially, ORSV was confirmed as the causative agent of viral symptoms in orchid leaves via reverse transcription-polymerase chain reaction (RT-PCR) analysis. Meristems from infected plants were cultured to generate PLBs, which in sequence were repeatedly subcultured up to four times. RT-PCR and quantitative RT-PCR analyses revealed that while ORSV was undetectable in shoots derived from the first subculture, complete elimination of the virus required at least a second subculture. Genetic analysis using inter-simple sequence repeat markers indicated no somaclonal variation between regenerated plants and the mother plant, suggesting that genetic consistency was maintained. Conclusion Overall, our findings demonstrate that subculturing PLBs for a second time is ideal for producing genetically stable, ORSV-free Cymbidium orchids, thus offering a practical means of generating genetically stable, virus-free plants and enhancing plant health and quality in the orchid industry.

We overexpressed the 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase gene (acdS), which encodes the enzyme responsible for the degradation of an ethylene precursor (ACC), in Petunia hybrida cv. Mirage Rose. We investigated whether acdS overexpression rendered the petunia more tolerant to copper (Cu) stress. The transgenic plants exhibited greater tolerance to Cu stress than wild type (WT) plants, as evidenced by better plant growth and physiological performances. Additionally, the transgenic plants displayed significantly suppressed ethylene production and related genes, elevated expression of antioxidant and proline activity-related genes, reduced accumulation of reactive oxygen species and Cu, and increased expression of genes regulating heavy metal when compared to the WT plants. These findings elucidate the mechanism by which acdS imparts Cu stress tolerance, suggesting that overexpressing acdS in plants can facilitate their resilience to Cu stress.

Ethylene plays a critical signaling role in the abiotic stress tolerance mechanism. However, the role of ethylene in regulating abiotic stress tolerance in petunia has not been well-investigated, and the underlying molecular mechanism by which ethylene regulates abiotic stress tolerance is still unknown. Therefore, we examined the involvement of ethylene in salt and drought stress tolerance of petunia using the petunia wild type cv. “Merage Rose” and the ethylene biosynthesis genes (PhACO1 and PhACO3)-edited mutants (phaco1 and phaco3). Here, we discovered that editing PhACO1 and PhACO3 reduced ethylene production in the mutants, and mutants were more sensitive to salt and drought stress than the wild type (WT). This was proven by the better outcomes of plant growth and physiological parameters and ion homeostasis in WT over the mutants. Molecular analysis revealed that the expression levels of the genes associated with antioxidant, proline synthesis, ABA synthesis and signaling, and ethylene signaling differed significantly between the WT and mutants, indicating the role of ethylene in the transcriptional regulation of the genes associated with abiotic stress tolerance. This study highlights the involvement of ethylene in abiotic stress adaptation and provides a physiological and molecular understanding of the role of ethylene in abiotic stress response in petunia. Furthermore, the finding alerts researchers to consider the negative effects of ethylene reduction on abiotic stress tolerance when editing the ethylene biosynthesis genes to improve the postharvest quality of horticultural crops.

The role of acdS, which encodes the 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase enzyme, in extending flower longevity and improving tolerance to cadmium (Cd) stress was assessed using transgenic Petunia hybrida cv. ‘Mirage Rose’ overexpressing acdS and wild-type (WT) plants. The overexpression of acdS reduced ethylene production in floral tissue via suppression of ethylene-related genes and improved flower longevity, approximately 2 to 4 days longer than WT flowers. Under Cd stress, acdS significantly reduced Cd-induced ethylene production in vegetable tissues of transgenic plants through suppression of ethylene-related genes. This resulted in a lower accumulation of ethylene-induced reactive oxygen species (ROS) in the transgenic plants than in WT plants. In addition, expression of the genes involved in the activities of antioxidant and proline synthesis as well as the metal chelation process was also higher in the former than in the latter. Moreover, Cd accumulation was significantly higher in WT plants than in the transgenic plants. These results are linked to the greater tolerance of transgenic plants to Cd stress than the WT plants, which was determined based on plant growth and physiological performance. These results highlight the potential applicability of using acdS to extend flower longevity of ornamental bedding plants and also reveal the mechanism by which acdS improves Cd-stress tolerance. We suggest that acdS overexpression in plants can extend flower longevity and also help reduce the negative impact of Cd-induced ethylene on plant growth when the plants are unavoidably cultivated in Cd-contaminated soil.