Over the last several decades, plants have been developed as a platform for the production of useful recombinant proteins due to a number of advantages, including rapid production and scalability, the ability to produce unique glycoforms, and the intrinsic safety of food crops. The expression methods used to produce target proteins are divided into stable and transient systems depending on applications that use whole plants or minimally processed forms. In the early stages of research, stable expression systems were mostly used; however, in recent years, transient expression systems have been preferred. The production of the plant itself, which produces recombinant proteins, is currently divided into two major approaches, open-field cultivation and closed-indoor systems. The latter encompasses such regimes as greenhouses, vertical farming units, cell bioreactors, and hydroponic systems. Various aspects of each system will be discussed in this review, which focuses mainly on practical examples and commercially feasible approaches.

The AGAMOUS (AG) family of MADS-box genes plays important roles in controlling the development of the reproductive organs of flowering plants. To understand the molecular mechanisms behind the floral development in the orchid, we isolated and characterized two AG-like genes from Phalaenopsis that we denoted PhalAG1 and PhalAG2. Phylogenetic analysis indicated that PhalAG1 and PhalAG2 fall into different phylogenetic positions in the AG gene family as they belong to the C- and D-lineages, respectively. Reverse transcription-polymerase chair reaction (RT-PCR) analyses showed that PhalAG1 and PhalAG2 transcripts were detected in flower buds but not in vegetative organs. Moreover, in situ hybridization experiments revealed that PhalAG1 and PhalAG2 hybridization signals were observed in the lip, column, and ovule during the floral development of Phalaenopsis, with little difference between the expression patterns of the two genes. These results suggest that both AG-like genes in Phalaenopsis act redundantly with each other in floral development.

Plant MADS-box genes encode transcriptional regulators that are critical for a number of developmental processes, such as the establishment of floral organ identity, flowering time, and fruit development. It appears that the MADS-box gene family has undergone considerable gene duplication and divergence within various angiosperm lineages. SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1)/Tomato MADS-box gene 3 (TM3)-like genes are members of the MADS-box gene family and have undergone repeated duplication events. Here, we isolated and characterized the SOC1/TM3-like gene TrcMADS1 from Trillium camtschatcense (Trilliaceae) to infer the ancestral function of SOC1/TM3-like genes. The alignment of SOC1/TM3-like genes revealed the presence of a highly conserved region in the C-terminal of predicted protein sequences, designated the SOC1 motif. Phylogenetic analysis indicated that TrcMADS1 is at the basal position of the SOC1/TM3-like gene family. The TrcMADS1 mRNA was detected in both vegetative and reproductive organs by RT-PCR. Our results suggest that duplicated copies of SOC1/TM3-like gene evolved to become variously functionally specialized.

An efficient in vitro protocol has been established for somatic embryogenesis and plantlet conversion of Korean wild ginseng (Panax ginseng Meyer). Wild-type and mutant adventitious roots derived from the ginseng produced calluses on Murashige and Skoog (MS) medium supplemented with 0.5 mg/L 2,4-dichlorophenoxyacetic acid and 0.3 mg/L kinetin; 53.3% of the explants formed callus. Embryogenic callus proliferation and somatic embryo induction occurred on MS medium containing 0.5 mg/L 2,4-dichlorophenoxyacetic acid. The induced somatic embryos further developed to maturity on MS medium with 5 mg/L gibberellic acid, and 85% of them germinated. The germinated embryos were developed to shoots and elongated on MS medium with 5 mg/L gibberellic acid. The shoots developed into plants with well-developed taproots on one-third strength Schenk and Hildebrandt basal medium supplemented with 0.25 mg/L 1-naphthaleneacetic acid. When the plants were transferred to soil, about 30% of the regenerated plants developed into normal plants.

MADS-box genes encode transcriptional regulators that are critical for a number of developmental processes. In the MADS-box gene family, the SEPAL-LATA (SEP) gene subfamily plays an important role in controlling the development of floral organs in flowering plants. To understand the molecular mechanisms of floral development in Asparagus, we isolated and characterized several SEP-like genes from dioecious Asparagus officinalis and hermaphrodite A. virgatus: AOMADS1, AOMADS2, AOMADS3, and AVMADS1, AVMADS2, AVMADS3, respectively. Through alignment of the predicted amino acid sequences of various SEP-like genes, we defined three characteristic motifs in the C-terminal region of the genes: SEP motif I, SEP/ AGL6 motif, and SEP motif II. Of the genes we isolated, AOMADS3 and AVMADS3 had lost the SEP motif II. Phylogenetic analysis revealed that AOMADS1, AO-MADS2, AVMADS1, and AVMADS2 were closely related to SEP3 from Arabidopsis, whereas AOMADS3 and AVMADS3 were classified in different clade which is far related to SEP3 gene. Northern hybridization and RT-PCR showed that three SEP-like genes in A. officinalis were specifically expressed in the flower buds. In addition, PCR RFLP showed that there was no significant difference in the amount of transcripts of AO-MADS1 and AOMADS2. These results suggest that AOMADS1 and AOMADS2 may be redundant genes. In contrast, the expression of AOMADS3 was weaker than that of AOMADS1 or AOMADS2, suggesting that the function of AOMADS3 may be different than that of AOMADS1 or AOMADS2.