This cover illustrates the concept of synthetic biology and bioproduction in plants. Plants absorb CO₂ and, through the introduction of gene circuits from other organisms or artificially generated, can produce a variety of products, including pharmaceuticals, fine chemicals, raw materials for bioplastics, biofuels, and more.
The concepts of gene editing, metabolic pathway shifting, gene network manipulation, and the DBTL (Design-Build-Test-Learn) cycle are crucial for the implementation of synthetic biology and bioproduction in plants. The goal of synthetic biology and bioproduction in plants is to contribute to carbon recycling, which is a central component of the bioeconomy. Chemical structures of lignin, acteoside, menthol, corosolic acid, and isoprene are described clockwise from left top.

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The anthocyanin related glutathione S-transferase (GST) belongs to the Phi class of the GST family and has been regarded to play a role in anthocyanin transport to the vacuole. We isolated its orthologue from the torenia petal. Transgenic plants transcribing GST double stranded RNA were generated from a blue torenia. Resultant plants exhibited a range of flower colors, from blue to almost white. However, pure white flowers were not obtained in site of significant downregulation of the GST transcript. Anthocyanin levels in the petals of the transgenic plants decreased, whereas flavone levels remained unchanged. Anthocyanins and flavones may be transported to the vacuole through different mechanisms (Akagi et al, pp. 147–151) .

AtGTLP is a novel trans-Golgi-localized Arabidopsis protein with characteristics of a glycosyltransferase. The micrograph shows root cells after double visualization of Arabidopsis line co-expressing AtGTLP-mGFP and a mRFP-tagged trans-Golgi marker, ST. Subcellular localization was observed using Zeiss LSM980 confocal laser scanning microscope system equipped with Plan-Apochromat 63x/1.40 Oil DIC M27 immersion objective. Adapted from: Rzepecka et al. (pp. 35–44).

Plant cell wall plays important roles in the regulation of plant growth/development and affects the quality of plant-derived foods. Genetic variability of cell wall components within a plant species, however, has not been well understood. In this issue, Zamorski et al. showed that the endosperm cell walls from 89 rice varieties were clearly classified into two groups, depending on the presence/absence of β-1,4-linked glucomannan (See Zamorski et al, pp. 321–336). Immunoelectron microscopic observation of developing rice grains with an anti-Man4 antibody often detected the accumulation of glucomannan (indicated by the presence of gold particles) in the middle portion of the thick aleurone cell walls of a glucomannan-positive variety, Fujisaka-5, suggesting that the glucomannan was synthesized in the early stage of endosperm development but the synthesis was downregulated during the secondary thickening process associated with the differentiation of aleurone layer.

This cover shows photos of genome-edited under research and development in Japan.
(Top left) Site-directed mutagenesis in two GmPPD genes in soybean (Glycine max). Photographed by Jaechol Sim using a smartphone camera (Galaxy S10 5G) at Hokkaido University (Sapporo, Japan).
(Top right) Double-flowered gentian produced by genome editing of AG1 gene. Photographed by Masahiro Nishihara using a digital camera (Olympus E-M10) at Iwate Biotechnology Research Center (Iwate, Japan).
(Bottom left) Field cultivation of genome-edited wheat. Photographed by Fumitaka Abe using a smartphone camera (SONY Xperia) at The National Agriculture and Food Research Organization (NARO) (Ibaraki, Japan).
(Bottom right) Harvesting genome-edited potato tubers with reduced accumulation of steroidal glycoalkaloids grown in an open field. Photographed by Yuki Sasakawa using a digital camera (Lumix DMC-GX7) at NARO (Ibaraki, Japan).
Designed by Shuhei Yasumoto.

Intergeneric hybridization is an effective strategy for increasing variation and conferring useful traits to organisms. In this study, intergeneric hybrids of marguerite (Argyranthemum frutescens) and two Rhodanthemum species (R. hosmariense and R. catananche) were obtained via ovule culture (See Katsuoka et al., pp. 135–143). The two resulting hybrids exhibited blooming characteristics inherited from both parents. The leaf shape and other morphological traits of the progenies were intermediate between those of the parents. This study provides a basis for further development of Argyranthemum breeding, especially that of a series of hybrid cultivars with different flower colors.
These photographs were taken using an iPhone 7 at the Izu Agricultural Research Center (Shizuoka, Japan) in March 2022.

Optimal media of Piriformospora indica to release effective VOC for plant growth. Utilization of beneficial microorganism will overcome food shortage issue by enhancing crop productivity as well as conserving environmental balance. The fungus Piriformospora indica is a beneficial root-colonizing microorganism that can promote plant resistance and growth by producing diffusible and/or volatile organic compounds (VOCs). The cover photography shows that P. indica grown on different media releases different VOCs by altering the metabolism and induces differential effects on plant growth. (See Bayubaskara et al, pp. 117–121)
This photograph was taken by Muhammad Fito Bayubaskara. These pictures were taken using a digital camera (Nikon D3000) at the Academia Sinica Biotechnology Center in Southern Taiwan (Tainan, Taiwan) in 2021-2022.

A histidine auxotrophic Marchantia polymorpha strain was generated using CRISPR/Cas9-mediated genome editing, which can be used for biocontainment. An auxotrophic selective marker gene applicable to the auxotrophic strain was also developed to select transformants without antibiotic selection. The cover photograph shows a regenerated thallus transformed with Agrobacterium tumefaciens harboring a binary vector pMpGWBhis03-Citrine-NLS that encodes a fluorescent protein and the auxotrophic selective marker protein. Green and red colors indicate fluorescence from the fluorescent protein and chloroplasts, respectively. (See Fukushima and Kodama, pp. 345–354)
This photograph was taken by Tatsushi Fukushima at Utsunomiya University (Tochigi, Japan) using an MZ16F stereo fluorescence microscope (Leica Microsystems) and a DP73 digital camera (Olympus).

Garden stock (Matthiola incana) is an important floricultural plant that blooms from winter to spring. This study successfully obtained stable transgenic plants from M. incana (Tanahara et al., pp. 273–280). The leaf sections were cocultivated with the Agrobacterium tumefaciens GV3101 for 5 days, and then obtained hygromycin-resistant calli in a selection medium supplemented with 12.5 µM fipexide (FPX). Then, the transgenic calli were transferred to shoot formation medium. This protocol achieved a 0.7% transformation frequency. FPX is considered a breakthrough for establishing the transformation protocol of M. incana.
Location: Faculty of Agriculture, Shizuoka University (836 Ohya, Suruga-ku, Shizuoka, Japan)
Photography equipment: CASIO EXILM EX-ZR850

Transgenic rice seeds segregating proUBQ:GFP (left) and pro35S:GFP (right) at T1 generation. Strong GFP signals were observed in proUBQ:GFP, indicating the activity of this promoter is stable in rice. On the other hand, pro35S:GFP was frequently silenced in rice. Using this ubiquitin promoter from maize, a simple series of binary vectors for rice with gateway system was developed (See Tsuda et al., pp. 139–146). Seeds were illuminated using a blue LED and the photograph was taken by a digital camera (Olympus TG-6) with a GFP filter.

Glycogen synthase kinase 3 (GSK3) family has important roles in regulating cell proliferation and differentiation during various developmental processes in angiosperms. However, in the plant lineages except angiosperms, the function of GSK3s especially in the cell differentiation processes remains unknown. The model bryophyte Marchantia polymorpha has a single GSK3-like kinase MpGSK. Overexpression of MpGSK reduced the size of the meristem region, which consists of the stem cell zone (SCZ) including apical cells, and the dividing and differentiating cell zone (DDCZ). Conversely, Mpgsk loss-of-function mutants exhibited an undifferentiated cell mass phenotype. These findings indicate that MpGSK is involved in the regulation of cell differentiation. The cover shows the meristem region of M. polymorpha (proMpE2F:XVE>>MpGSK-L-1 cultured without β-estradiol) visualized by EdU assay (red) and cell wall staining (white). (See Furuya et al., pp. 65–72)

Photographed by Tomoyuki Furuya, Kobe University (Kobe, Japan) using the FLUOVIEW FV1000 (Olympus).

The commercial use of genetically modified (GM) crops requires prior assessment of potential risks to the environment which may arise during open field production or distribution. In this study, we conducted confined field trials to assess environmental risks for Japan-based commercial production of GM tomato plants accumulating miraculin, a taste-altering protein that causes sour taste to be perceived as sweet (Hiwasa-Tanase et al., pp. 421–431). The cover shows photos of the confined field (bottom left) used for environmental risk assessment, GM and non-GM tomatoes that were cultivated for assessment of plant morphology and growth characteristics (bottom right), GM and non-GM tomato plants on the first day of overwintering ability test (top left), and tomato seedlings at 20 days post cold treatment during the early stages of growth (top right). In the photo showing cold tolerance tests (top right), the left and middle trays contain cold-treated non-GM and GM seedlings respectively, while the right tray contains seedlings without cold treatment.

Photographed and designed by Kyoko Hiwasa-Tanase. These pictures were taken using a digital camera (Canon SX280 HS) at the T-PIRC Gene Research Center, University of Tsukuba (Ibaraki, Japan) in 2018–2019.