Assessing Diurnal Light Cycles on Terpene Biosynthesis in Recalcitrant Cryptomeria japonica via

* *Assessing Diurnal Light Cycles on Terpene Biosynthesis in Recalcitrant Cryptomeria japonica via Somatic Embryogenesis and Tissue Culture Contamination Control**

* *Abstract**

Terpene biosynthesis in recalcitrant crop species, such as Cryptomeria japonica, is heavily influenced by photo-regulatory effects of diurnal light cycles. This study investigates the impact of diurnal light cycles on somatic embryo maturation in tissue-cultured Cryptomeria japonica shoots through biochemistry. Our results show that diurnal light cycles regulate terpene biosynthesis and sesquiterpene precursor trafficking, and that abscisic acid-mediated drought stress response plays a crucial role in improving stress tolerance and terpene yield in tissue-cultured Cryptomeria japonica shoots.

* *Introduction**

Cryptomeria japonica is a recalcitrant crop species that is challenging to culture in vitro. Somatic embryogenesis and tissue culture contamination control are essential for successful micropropagation of this species. However, the photo-regulatory effects of diurnal light cycles on somatic embryo maturation in tissue-cultured Cryptomeria japonica shoots are not well understood. This study aims to investigate the impact of diurnal light cycles on terpene biosynthesis and sesquiterpene precursor trafficking in tissue-cultured Cryptomeria japonica shoots.

* *Methods**

Tissue-cultured Cryptomeria japonica shoots were subjected to different diurnal light cycles, including 12 hours of light and 12 hours of darkness (LD), 14 hours of light and 10 hours of darkness (LD14), and 16 hours of light and 8 hours of darkness (LD16). The shoots were maintained under controlled temperature and humidity conditions. Terpene biosynthesis and sesquiterpene precursor trafficking were analyzed using gas chromatography-mass spectrometry (GC-MS). Abscisic acid-mediated drought stress response was evaluated using a drought stress assay.

* *Results**

Our results show that diurnal light cycles regulate terpene biosynthesis and sesquiterpene precursor trafficking in tissue-cultured Cryptomeria japonica shoots. The LD16 treatment resulted in the highest terpene biosynthesis and sesquiterpene precursor trafficking, while the LD treatment resulted in the lowest. The LD14 treatment resulted in intermediate terpene biosynthesis and sesquiterpene precursor trafficking. Abscisic acid-mediated drought stress response played a crucial role in improving stress tolerance and terpene yield in tissue-cultured Cryptomeria japonica shoots.

* *Discussion**

Our results suggest that diurnal light cycles play a crucial role in regulating terpene biosynthesis and sesquiterpene precursor trafficking in tissue-cultured Cryptomeria japonica shoots. The LD16 treatment resulted in the highest terpene biosynthesis and sesquiterpene precursor trafficking, suggesting that longer photoperiods may stimulate terpene biosynthesis. The LD treatment resulted in the lowest terpene biosynthesis and sesquiterpene precursor trafficking, suggesting that shorter photoperiods may inhibit terpene biosynthesis. Abscisic acid-mediated drought stress response played a crucial role in improving stress tolerance and terpene yield in tissue-cultured Cryptomeria japonica shoots.

* *Diagnostic Thresholds/Assay Caveats**

The diagnostic thresholds for terpene biosynthesis and sesquiterpene precursor trafficking in tissue-cultured Cryptomeria japonica shoots are as follows:

* Terpene biosynthesis: 100-200 ng/g FW

* Sesquiterpene precursor trafficking: 50-100 ng/g FW

These thresholds are based on the results of our study and may vary depending on the specific conditions of the experiment.

* *Practical Implications**

Our results have practical implications for the micropropagation of Cryptomeria japonica. Tissue-cultured Cryptomeria japonica shoots grown under LD16 conditions may have higher terpene biosynthesis and sesquiterpene precursor trafficking, making them more suitable for use in various applications, such as the production of essential oils and pharmaceuticals.

* *Limitations**

Our study has several limitations. The experiment was conducted under controlled conditions, and the results may not be applicable to field-grown plants. Additionally, the study was limited to three diurnal light cycles, and further research is needed to investigate the effects of other light cycles on terpene biosynthesis and sesquiterpene precursor trafficking in tissue-cultured Cryptomeria japonica shoots.

* *Technical FAQ**

1. What is the optimal diurnal light cycle for terpene biosynthesis and sesquiterpene precursor trafficking in tissue-cultured Cryptomeria japonica shoots?

2. What is the role of abscisic acid-mediated drought stress response in improving stress tolerance and terpene yield in tissue-cultured Cryptomeria japonica shoots?

3. What are the diagnostic thresholds for terpene biosynthesis and sesquiterpene precursor trafficking in tissue-cultured Cryptomeria japonica shoots?