Physiological and Growth Response of Pepper (Capsicum annum L.) Seedlings to Supplementary Red/Blue Light Revealed through Transcriptomic Analysis

Abstract

Red and blue light have great effects on physiological processes and growth of plants. In this experiment, we investigated the physiological and growth response of pepper (Capsicum annuum L.) to supplementary red:blue (4:1) light for 1 h (T1), 3 h (T2), and 5 h (T3), and the full-spectrum light-emitting diodes, LEDs, as control (CK). Thirty-day-old seedlings were grown under these treatments for 20 days in a climate-controlled room before data measurement. The results showed that the light treatments significantly (p < 0.05) affected the photosynthesis and growth indexes as well as gene expression in the pepper seedlings. Plants under T2 generally had better performance in terms of seedling growth. A total of 124, 1283, and 1091 differentially expressed genes were found in CK vs. T1, CK vs. T2, and CK vs. T3, respectively. Among the treatments, T2 in comparison with CK had 705 upregulated and 578 downregulated differentially expressed genes (DEGs). We also found that CPRF2, Paggis, HLIPS, GIGANTEA, LSH1, and FTSH genes were expressed differently under the various light treatments. Based on GeneOntology (GO) enrichment analysis, DEGs were significantly enriched on 15 GO terms of which xyloglucan:xyloglucosyl transferase activity and apoplastic, cellular polysaccharide metabolic, and cellular carbohydrate metabolic processes were closely related to light responses. A total of 96 genes that are related to plant-pathogen interaction, zeatin biosynthesis, plant hormone signal transduction, and wax/cutin/suberine biosynthesis which are involved in the pathway of light reaction in plants were significantly enriched in T2 plants compared with plants under CK. The application of red:blue light at 4:1 for 3 h improved the growth of pepper seedlings better than the other treatments and this can be tested under the Chinese Solar Greenhouse condition.The exposure of 'Green Oak Leaf' lettuce plants to fluorescent lamps with blue or red LEDs increased stem diameter, leaf area, leaf number, and dry biomass of shoot [5]. Brown et al. indicated that red LEDs in combination with other wavelengths of light may be suitable for the culture of plants under climate-controlled environments [6]. The application of red and blue light also affected biomass accumulation, pigment synthesis, antioxidants, and phenolic compounds. Moreover, chlorophyll contents increased significantly with increasing blue light in tomato, cucumber, radish, and pepper as compared with control plants [7]. Košvancová-Zitová et al. reported that irradiance with high B:R ratio (3:1) increased the rate of photosynthesis in Fagus sylvatica better than irradiance with low B:R (1:3) ratio [8]. In another experiment, Son et al. reported that the total antioxidant phenolic concentrations of lettuce plants increased as the proportion of blue light was increased [9]. Furthermore, different proportions of red and blue light have different effects on plant growth. A study showed that photosynthesis and yield of plants treated with LED-A (R:B = 6:3) were improved as compared to...

Effects of red and blue light on leaf anatomy, CO2 assimilation, and the photosynthetic electron transport capacity of sweet pepper (Capsicum annuum L.) seedlings

“…Biomass is an important indicator of seedling quality. In this study, the seedling DW under RB was signi cantly greater than those under other treatments, which suggested that this spectrum was optimal because it promoted plant development and drove photosynthesis by increasing Chl a and total Chl contents in the seedlings [33,40]. Previous studies also found that mixed R and B light could promote fresh weight (FW) and DW in many other plant species, such as chrysanthemum, upland cotton and tomato [41][42][43].…”

“…The popularity of sweet pepper (Capsicum annuum L.) for fresh market consumption or in ready-to-eat food has risen signi cantly during the past decades and these peppers are mostly produced in protected environments [31]. Mixed R and B light has an apparent in uence on the growth and physiology of pepper plants [26,32,33]. Gaining a more complete mechanistic picture of how plants adapt and respond to R and B light quality is important since light quality plays important roles in growth and physiology.…”

Laser Irradiation Effects at Different Wavelengths on Phenology and Yield Components of Pretreated Maize Seed

“…Therefore, more attention was given in recent years to physical factors that may be applicable to processing of sowing material [1,2]. In order to ensure a high seed performance, various methods of processing are used, including chemical preparations, such as seed inoculation by chemical material and growth regulators, as well as physical factors, including laser light and magnetic fields [3][4][5][6][7][8]. Pre-sowing treatment was applied in order to stimulate the seeds to better germinate and grow faster in various sowing conditions [9].…”

“…Research on the effects of pre-sowing bio-stimulation on plant crops showed that the best results of this treatment are obtained for plant vegetables, rather than for cereals and root crops. After applying radiation laser to tomatoes and cucumbers, a significant increase in yield was found, which accelerated the ripening and produced better fruit quality [8,22]. One of the methods of seed refinement is irradiation; a divergent beam laser light provides energy to modify physiological and biochemical processes, causing an increase in the field's performance to rise and yield crops [23].…”

Effects of red and blue light on leaf anatomy, CO2 assimilation and the photosynthetic electron transport capacity of sweet pepper (Capsicum annuum L.) seedlings

“…The popularity of sweet pepper (Capsicum annuum L.) for fresh market consumption or in ready-to-eat food has risen significantly during the past decades and these peppers are mostly produced in protected environments [31]. Mixed R and B light has an apparent influence on the growth and physiology of pepper plants [26,32,33]. Gaining a more complete mechanistic picture of how plants adapt and respond to R and B light quality is important since light quality plays important roles in growth and physiology.…”