Cymbidium faberi, one of the most famous oriental orchids, has a distinct flower scent, which increases its economic value. However, the molecular mechanism of the flower scent biosynthesis was unclear prior to this study. Methyl jasmonate (MeJA) is one of the main volatile organic compounds (VOC) produced by the flowers of C. faberi. In this study, unigene 79,363 from comparative transcriptome analysis was selected for further investigation. A transcriptome comparison between blooming and withered flowers of C. faberi yielded a total of 9409 differentially expressed genes (DEGs), 558 of which were assigned to 258 pathways. The top ten pathways included α-linolenic acid metabolism, pyruvate metabolism and fatty acid degradation, which contributed to the conversion of α-linolenic acid to MeJA. One of the DEGs, jasmonic acid carboxyl methyltransferase (CfJMT, Unigene 79,363) was highly expressed in the blooming flower of C. faberi, but was barely detected in leaves and roots. Although the ectopic expression of CfJMT in tomato could not increase the MeJA content, the expression levels of endogenous MeJA biosynthesis genes were influenced, especially in the wound treatment, indicating that CfJMT may participate in the response to abiotic stresses. This study provides a basis for elucidating the molecular mechanism of flower scent biosynthesis in C. faberi, which is beneficial for the genetically informed breeding of new cultivars of the economically valuable oriental orchids.

Background: Cymbidium faberi is one of the oldest cultivars of oriental orchids, with an elegant flower fragrance. In order to investigate the molecular mechanism and the functions of related proteins in the methyl jasmonate (MeJA) signaling pathway, one of the main components of flower fragrance in C. faberi, yeast one- and two-hybrid three-frame cDNA libraries were constructed. Results: In this study, a modified cDNA library used for yeast one- and two-hybrid screening was successfully constructed, with a recombinant efficiency of 95%. The lengths of inserted fragments ranged from 750~3000 bp, and the library capacity reached 6 × 10⁹ CFU/ μg of cDNA insert, which was suitable for the requirements of subsequent screening. Finally, a homologous protein related with pathogenesis was screened out by the bait vector of CfbHLH36, which may participate in the MeJA signaling pathway. Conclusion: The yeast one- and two-hybrid library of C. faberi provides large amounts of useful information for the functional genomics research in C. faberi, and this method could also be applied to other plants to screen DNA-protein and protein-protein interactions.

Sarcandra glabra has significant metabolically active bioingredients of pharmaceutical importance. The deficiency of molecular markers for S. glabra is a hindrance in molecular breeding for genetic improvement. In this study, 57.756 million pair‐end reads were generated by transcriptome sequencing in S. glabra (Thunb.) Nakai and its subspecies S. glabra ssp. brachystachys. A total of 141,954 unigenes with 646.63 bp average length were assembled. A total of 25,620 simple sequence repeats, 726,476 single nucleotide polymorphisms, and 42,939 insertions and deletions were identified, and the associated unigenes and differentially expressed genes were characterized. This work enhanced the molecular marker resources and will facilitate molecular breeding and gene mining in S. glabra spp.

Roses are among the most widely produced cut flowers, with important ornamental and economic value in the flower market. In order to investigate how to regulate flowering periods, the negative regulator of GA biosynthesis RcSPY was cloned from Rosa chinensis and ectopically expressed in tobacco. The overexpression of RcSPY in SPY4 transgenic tobacco significantly increased plant height. Antisense interference with the conserved SPY domain of RcSPY led to GA accumulation in SPY5 transgenic tobacco plants, and antisense interference with the conserved TPR repeats of RcSPY resulted in late flowering in SPY6 transgenic tobacco plants. This result suggests that RcSPY is a negative regulator of GA biosynthesis, since the knock-down of RcSPY increased GA content. However, other phenotypes displayed by transgenic tobacco plants may not be caused by changes of GA content, but rather be the direct effects of RcSPY. Therefore, RcSPY not only participates in GA biosynthesis, but also plays a role in other vegetative and reproductive plant behaviors not related to GA. This result provides theoretical support for the molecular breeding of new cultivars of rose plants.

Oriental orchids possess great potential in the consumer market because of their diverse leaf and flower patterns and enchanting fragrance. Nevertheless, their long growth period, stringent growth environment requirements, low germination rates, and limited transformation methods pose significant obstacles to genetic improvement. To improve the regeneration efficiency of oriental orchids and enhance their transformation efficiency, the solid–liquid oscillation–solid alternating cultivation mode was used to efficiently obtain stable transformants of Cymbidium orchids in this study. The results showed that within approximately 2 months, the regeneration rate of C. goeringii derived from protocorm-like bodies reached a remarkable 77.30% with this method. The transformation efficiency of C. goeringii achieved through polymerase chain reaction amplification was 18.66% when inoculated with Agrobacterium LBA4404, and the positive transformation rate reached 75.03%. This experimental result was further validated by β-glucuronidase staining and green fluorescent protein fluorescence detection. This methodology significantly increased the positive transformation rate and shortened the regeneration period of C. goeringii . Furthermore, this cultivation mode was successfully implemented for C. faberi and C. ensifolium . Therefore, the solid–liquid oscillation–solid alternating cultivation mode provides a technical basis for efficient transformation, which will promote the rapid development of genetically improved oriental orchids.