Regulation of anthocyanin synthesis in red lettuce in plant factory conditions: A review.

Anthocyanins, natural pigments known for their vibrant hues and beneficial properties, undergo intricate genetic control. However, red vegetables grown in plant factories frequently exhibit reduced anthocyanin synthesis compared to those in open fields due to factors like inadequate light, temperature, humidity, and nutrient availability. Comprehending these factors is essential for optimizing plant factory environments to enhance anthocyanin synthesis. This review insights the impact of physiological and genetic factors on the production of anthocyanins in red lettuce grown under controlled conditions. Further, we aim to gain a better understanding of the mechanisms involved in both synthesis and degradation of anthocyanins. Moreover, this review summarizes the identified regulators of anthocyanin synthesis in lettuce, addressing the gap in knowledge on controlling anthocyanin production in plant factories, with potential implications for various crops beyond red lettuce.

[Antidepressant activities of flavonoids from Glycyrrhiza uralensis and its neurogenesis protective effect in rats].

Adult rats chronic unpredictable stress model of depression (CUS) was adopted to elucidate the antidepressant pharmacological activity and related neurogenesis protective effect of the total flavonoids extract (licorice flavonoids, LF) from the Glycyrrhiza uralensis Fisch. cultivated locally in Ningxia. The rats were exposed to 9 kinds of unpredictable sequence of stressors and were given flavonoids (300 mg x kg(-1), 100 mg x kg(-1) and 30 mg x kg(-1)) for 28 days. The antidepressant effect was elucidated by open field test, forced swimming test and tail suspension test. The level of serum corticosterone was detected by radioimmunoassay. 5'-Bromo-2'-deoxyuridine (BrdU) labeling experiments was employed to study the neurogenesis protective activities. The flavonoids can increase the sum of line crosses and number of rears, and decrease the number of fecal boli produced in the open field test of the CUS rats. Also the flavonoids can decrease the immobility time in forced swim test as well as in the tail suspension test. In addition, the flavonoids (300 mg x kg(-1)) can decrease the serum corticosterone level of the CUS rats, and increase the number of the new born BrdU positive progenitor cells at the subgranular zone (SGZ) of dentate gyrus (DG) region in hippocampus. The results demonstrated that the total flavonoids extract from the cultivated Glycyrrhiza uralensis Fisch. could produce the anti-depressive effect on chronic unpredictable stress of depression model rats and its mechanism may be associated with its neurogenesis protective effect.

Morphology, Photosynthetic Traits, and Nutritional Quality of Lettuce Plants as Affected by Green Light Substituting Proportion of Blue and Red Light.

Green light, as part of the photosynthetically active radiation, has been proven to have high photosynthetic efficiency once absorbed by plant leaves and can regulate plant physiological activities. However, few studies have investigated the appropriate and efficient way of using the green light for plant production. Thus, the objective of this study was to investigate a moderate amount of green light, partially replacing red and blue light, for plant growth and development. In this experiment, four treatments were set up by adjusting the relative amount of green light as 0 (RB), 30 (G30), 60 (G60), and 90 (G90) µmol m-2 s-1, respectively, with a total photosynthetic photon flux density of 200 µmol m-2 s-1 and a fixed red-to-blue ratio of 4:1. Lettuce (Lactuca sativa cv. 'Tiberius') plant growth and morphology, stomatal characteristics, light absorptance and transmittance, photosynthetic characteristics, and nutritional quality were investigated. The results showed that: (1) shoot dry weight increased by 16.3 and 24.5% and leaf area increased by 11.9 and 16.2% under G30 and G60, respectively, compared with those under RB. Plant stem length increased linearly with increasing green-to-blue light ratio; (2) light transmittance of lettuce leaf under treatments employing green light was higher than that under RB, especially in the green region; (3) stomatal density increased, whereas stomatal aperture area decreased with the increase in the relative amount of green light; and (4) carbohydrate accumulation increased under G60 and G90. Soluble sugar contents under G60 and G90 increased by 39.4 and 19.4%, respectively. Nitrate contents under G30, G60, and G90 decreased by 26.2, 40.3, and 43.4%, respectively. The above results indicated that 15-30% green light replacing red and blue light effectively increased the yield and nutritional quality of lettuce plants.