This experiment was conducted in specially designed spectral chambers at the School of Science, Yunnan Agricultural University. A corresponding light panel was fixed above each spectral chamber. There were a total of 8 spectral chambers, one of which served as the dark control group, and the remaining seven were experimental groups corresponding to seven different light qualities: pink light (P), green light (G), red light (R), natural light (N), yellow light (Y), white light (W), and blue light (B). (Eight treatment groups were cultured in eight independent cultivation chambers, respectively. Each treatment group/chamber contained three independent cultivation bags, and each bag bore five fruiting bodies, resulting in a total of 15 fruiting bodies per treatment group/chamber). All fungal sticks used in this experiment were the “Shenzhou 16” space-mutation-bred strains cultivated by the Institute of Botany, Chinese Academy of Sciences. The light/dark (L/D) cycle for each experimental group was 12 h/12 h. The light intensity for each light quality was set at 15 μmol m⁻² s⁻¹. The wavelength peaks of green light, red light, yellow light, and blue light are 525 nm, 660 nm, 585 nm, and 460 nm, respectively. The wavelength of pink light ranges from 400 nm to 760 nm with a peak at 665 nm. Natural light has a wavelength range of 400 nm to 760 nm and a peak wavelength of 583 nm, while white light has a wavelength range of 450 nm to 780 nm and a peak wavelength of 453 nm, measured approximately 10 cm below the light source using a spectroradiometer (HPCS-310X, Hangzhou Hopoo Color Technology Co., Ltd., Hangzhou, China). The temperature inside the spectral chambers was maintained between 20 °C and 25 °C. The relative humidity was 60 ± 5% before fruiting and 90% after fruiting initiation. Purified water was used throughout the growth process.

The length, width, and height of S. commune after fruiting were measured using a vernier caliper with Bluetooth data output. The dry weight and wet weight of S. commune from each spectral chamber after harvesting were measured using a precision electronic balance and a counterbalance scale, and the number of pilei per S. commune fruiting body was counted. Five fruiting bodies were randomly sampled from each treatment group, with three replicates per treatment group.

The color parameters of S. commune were measured using a portable precision colorimeter (WSC-1B, Shanghai Yidian Physical Optical Instrument Co., Ltd., Shanghai, China). The color data were processed to obtain C (color saturation), Hue (hue angle), CCI (color index), and a^*/b^* (color ratio). A higher C value indicates greater color saturation of the fungal species. Hue reflects the coloration of the fungal species. CCI can be used to evaluate changes in the color of the fungal species. a^*/b^* represents the comprehensive color index (13). The calculation formulas are shown as Equations 1–4.

The reflectance of S. commune was measured using a field spectroradiometer (IRIS, ASD Inc., Colorado, United States). A reflectance integrating sphere system, comprising the spectroradiometer, a collimated light source, and a white reference panel, was employed to collect the reflectance data from the samples. The measured spectral curves were subsequently analyzed and compiled.

This study measured and analyzed some of the amino acids in S. commune, totaling 17 types. When determining the types and content of amino acids in S. commune, the samples, reagents (such as acetonitrile, etc.; water conforms to GB/T 6682 Grade 1), and standard substance information are first prepared according to specific methods (14), including the preparation of reagents (e.g., 0.1 mol/L phosphate buffer) and standard solutions (stock solutions are prepared via derivation, constant volume adjustment, and filtration; series working solutions are obtained by diluting the stock solution accordingly). Next, the main instruments, such as the liquid chromatograph (Thermo U3000, Thermo Fisher Scientific, Massachusetts, United States) and the high-speed centrifuge (Eppendorf 5702, Eppendorf, Hamburg, Germany), etc. are set up. Subsequently, sample preparation is carried out: 0.1 g of the sample is weighed, hydrolyzed with hydrochloric acid, adjusted to neutral pH, and then centrifuged; the filtrate is derivatized (by adding buffer and DNFB solution for reaction), adjusted to constant volume, and filtered. Finally, under the set chromatographic conditions (mobile phase: acetonitrile, sodium acetate–acetic acid buffer solution, and water; column temperature: 37 °C; flow rate: 1.0 mL/min, etc.; using a specific gradient elution program), the processed samples and standard solutions are analyzed using the liquid chromatograph, thereby completing the amino acid determination.

When determining the polysaccharide content in S. commune, first clarify the required reagents (kits, standards; anhydrous ethanol and concentrated sulfuric acid need to be self-prepared), analytical balances and microplate readers, etc. During the extraction stage, the sample was dried, pulverized, and approximately 0.05 g was weighed, homogenized with water, and extracted in a 100 °C water bath for 2 h. After cooling and centrifugation, the supernatant was collected. A portion of the supernatant was mixed with anhydrous ethanol and left to stand at 4 °C overnight. Following another centrifugation step, the supernatant was discarded, and the precipitate was dissolved in water. For the measurement stage, the microplate reader was preheated and set to 490 nm. Standard solutions at different concentrations were prepared. Then, 200 μL of each standard or sample supernatant was mixed with the reagent and concentrated sulfuric acid. After water bath treatment and cooling, the absorbance was measured, and a standard curve was plotted. The absorbance of the sample was determined following the same procedure. Finally, the sample concentration was calculated based on the standard curve, and the polysaccharide content was computed using the appropriate formula. The calculation formulas are as follows, n represents the sample dilution factor, y represents the sample concentration obtained from the standard curve, and W represents the sample mass. The corresponding formula is provided in Equation 5.

Spectral data were collected using ViewSpecPro software. Data processing and variance analysis were performed using SPSS Statistics 25 software and Excel software. Graphs were generated using Origin 2024 and Origin 2025b. Orthogonal partial least squares discrimination analysis (OPLS-DA) was conducted with SIMCA 14.1 software. The data are expressed as mean ± standard deviation (SD). A p-value <0.05 was considered as statistically significant.

As shown in Figure 1, among the different light treatments, the growth rate of S. commune under red light treatment was the most significant during the early growth stage, as reflected in terms of length, width, and height. During the middle and late growth stages, the growth rates of S. commune under red light and natural light treatments were more significant compared to the other treatment groups, with overall levels remaining relatively high. The peak values for length, width, and height of S. commune under natural light treatment were 60.97 millimeters, 70.30 millimeters, and 33.68 millimeters (p < 0.05), respectively, while under red light treatment, the corresponding peak values were 56.48 millimeters, 64.39 millimeters, and 29.35 millimeters (p < 0.05). Therefore, the peak values under red light treatment were slightly lower than those under natural light treatment. Secondly, the growth in length, width, and height of S. commune under green light and pink light treatments was relatively lower, with differences in their respective growth rates and peak values. In contrast, the growth of S. commune under dark conditions was the slowest in terms of length, width, and height, and throughout the entire observation period, its length, width, and height consistently remained lower than those under other light treatments.

As shown in Figure 2, overall, the morphological traits of S. commune under pink light, green light, red light, and natural light treatments were favorable, exhibiting not only opened but also fan-shaped pileus. With the exception of the dark treatment and yellow light treatment, under which S. commune exhibited smaller morphology and relatively closed pileus, the growth under other light qualities was satisfactory. Compared to other light qualities, monochromatic yellow light is unsuitable for cultivating well-developed fruiting bodies (16).

In terms of leaf count, S. commune under green light treatment had the highest number of leaves, reaching 217. This was followed by natural light and red light treatments, with 209 and 198 leaves, respectively. Under pink light treatment, the leaf count was relatively high at 110, while white light, blue light, and dark treatments resulted in fewer leaves, with 33, 34, and 26 leaves, respectively. In contrast, yellow light treatment yielded the lowest leaf count, only 18. Overall, the influence of different light qualities on leaf count was quite significant. Green light was more conducive to increasing the number of leaves, whereas yellow light was unfavorable for leaf proliferation.

Regarding biomass under different light qualities, S. commune exhibited significant variations in fresh weight (FW), dry weight (DW), and consequently, moisture content (MC). The natural light treatment yielded the highest FW (163.50 g) and MC (83.24%) (p < 0.05), indicating that the increased biomass was predominantly due to water uptake rather than solid accumulation. In contrast, the red light treatment, while producing a moderate FW (80.06 g), resulted in the highest DW (38.12 g) and a correspondingly lower MC (52.39%). This suggests that red light is more conducive to the accumulation of dry matter. A similar pattern was observed under green light (FW: 83.10 g; DW: 35.30 g; MC: 57.52%). The lowest biomass values for both FW and DW were consistently recorded under yellow light (5.30 g and 3.60 g, respectively) and dark treatments (5.90 g and 4.11 g, respectively), with their MC also being relatively low (32.11 and 30.36%). Other treatments, such as pink, white, and blue light, resulted in low to moderate FW but were characterized by the lowest MC values (ranging from 24.05 to 44.49%) (p < 0.05), highlighting a general trend of efficient water utilization or limited water retention under these specific light conditions.

Overall, the analysis of biomass data (Table 1) indicates that light quality profoundly influences both biomass accumulation and water relations in S. commune. Natural light treatment resulted in the highest fresh weight, primarily due to its exceptionally high moisture content (83.24%), suggesting a strong promotive effect on water uptake or retention. In contrast, treatments with red and green light yielded fruiting bodies with a higher proportion of dry matter relative to their fresh weight, indicating a greater accumulation of solid biomass under these conditions. Blue and white light treatments produced fruiting bodies with the lowest moisture content (24.05 and 24.85%, respectively), implying the formation of denser tissue structures. Both yellow light and continuous darkness severely suppressed overall growth, resulting in the lowest absolute values for fresh and dry weight, and also limited water accumulation.

This study analyzed the leaf color of S. commune, as shown in Table 2. Compared with the control group, S. commune under natural light treatment showed a 74.63% increase in the C value, a 1.08% increase in the Hue value, and a 77.78% increase in the a^*/b^* value (p < 0.05) Under blue light treatment, the C value increased by 53.80%, the Hue value increased by 0.80%, and the a^*/b^* value increased by 74.10% (p < 0.05) The simulated color of S. commune under both blue and natural light treatments appeared darker. In contrast, under yellow light treatment, the C value decreased by 5.13%, and the simulated color was the lightest. For the other treatment groups, all parameters-C value, Hue value, CCI value, and a^*/b^* value-showed an increase compared to the control group. These changes are consistent with the potential enhanced synthesis of dark pigments, such as melanin. Meanwhile, yellow light (Y) led to the lightest coloration and a decrease in color saturation, suggesting an inhibition of such pigment synthesis. The Hue angle, which remained relatively stable across treatments, indicates that the fundamental color character was preserved, but its intensity and shade were modulated.

Overall, compared with the control, the color of S. commune under all light treatments exhibited distinct changes. These results further indicated that blue light and natural light treatments were more conducive to promoting a deeper coloration in S. commune, whereas yellow light treatment was unfavorable for enhancing its coloration. This phenomenon may be attributed to light regulation of the synthesis and degradation of specific pigments within the fungal cells. By modulating these key environmental signals, the light qualities are likely perceived by photoreceptor proteins in the fungal cells, thereby activating different pigment synthesis genes and leading to light quality-dependent color variations (17).

From a cultivation perspective, these results provide clear, actionable guidance. Color saturation (C value) and the a^*/b^* ratio are robust, non-destructive indicators of pigment development. Monitoring these parameters allows for real-time assessment of fungal physiological status. For cultivators aiming to achieve a deeper, more marketable coloration-often associated with specific phytochemical profiles-the application of blue or natural light is recommended. Conversely, yellow light should be avoided when this is the production goal.

As illustrated in Figure 3, the average reflectance spectra of S. commune under various light quality treatments spanned from 400 to 1,000 nm. A consistent reflectance trough was observed around 540 nm, while a prominent peak appeared near 930 nm across all treatments. Notably, the overall reflectance intensity varied significantly among light conditions, the yellow light treatment resulted in the highest reflectance, whereas green and pink light led to the lowest. White, natural, red, blue, and dark treatments exhibited moderate and comparable reflectance levels.

These spectral patterns can be attributed to the selective absorption of light by intracellular components. The light that is heavily absorbed creates reflectance troughs, whereas the unabsorbed light accordingly forms reflectance peaks (18).

The trough at 540 nm aligns with the absorption characteristics of carotenoids—a group of liposoluble pigments, including β-carotene, γ-carotene, and lutein, etc., prevalent in fungi, which absorb strongly in the blue-green region (400–550 nm) (19, 20). The peak at 930 nm may correspond to overtones of O–H and C–H stretching vibrations, often associated with water and organic compounds in fungal tissues.

Furthermore, light stress can trigger defense mechanisms such as cell wall thickening, which enhances light scattering and overall reflectance (21, 22). The elevated reflectance under yellow light may indicate a stress-adaptive response, potentially involving pigment accumulation or structural changes. Conversely, the suppressed reflectance under green and pink light suggests higher absorption or alternative physiological adaptations.

These findings highlight the potential of reflectance spectroscopy as a non-invasive tool for monitoring the physiological status of S. commune under different light regimes. Specifically, the reflectance features at 540 nm and 930 nm may serve as indicators of pigment dynamics and structural integrity, offering practical guidance for optimizing light conditions in controlled cultivation environments.

As shown in Table 3, all 17 amino acids detected in S. commune under each light treatment were free amino acids, among which proline (Pro), glutamic (Glu), and arginine (Arg) exhibited the highest contents (ranging from 2.23 to 4.80 mg/100 g), while Lys and Ile showed the lowest contents (ranging from 0.02 to 0.27 mg/100 g).

Among the 17 amino acids identified, threonine (Thr), lysine (Lys), valine (Val), methionine (Met), isoleucine (Ile), leucine (Leu), and phenylalanine (Phe) are essential amino acids (EAA), while aspartic acid (Asp), glutamic acid (Glu), serine (Ser), glycine (Gly), alanine (Ala), proline (Pro), tyrosine (Tyr), and cysteine (Cys) are non-essential amino acids (NEAA). Moreover, histidine (His) and arginine (Arg) are classified as conditionally essential amino acids (CEAA) (13).

As shown in Table 3 and Figure 4, compared to the control group, the total amino acid (TAA) content of Schizophyllum commune exhibited a declining trend under pink, green, red, yellow, and blue light treatments. In contrast, natural light and white light treatments promoted TAA accumulation. Similarly, the levels of essential amino acids (EAA), non-essential amino acids (NEAA), and conditionally essential amino acids (CEAA) followed a comparable pattern, decreasing under the aforementioned colored light treatments but increasing under natural and white light.

Furthermore, the 17 free amino acids identified in this study comprised 2 umami amino acids (Asp, Glu), 6 sweet amino acids (Thr, Ser, Gly, Ala, Pro, Cys), 8 bitter amino acids (Lys, Val, Met, Ile, Leu, Phe, His, Arg), and 1 tasteless amino acid (Tyr) (13). Compared to the control, the contents of key umami and sweet amino acids (Asp, Glu, Gly, Cys) were elevated under natural and white light, while showing a downward trend under the other light qualities. Notably, the orthogonal partial least squares-discriminant analysis (OPLS-DA) performed later identified five key amino acids with variable importance in projection (VIP) scores greater than 1, which were isoleucine (Ile), cysteine (Cys), methionine (Met), glycine (Gly), and valine (Val) (see section 3.7).

Among these VIP amino acids, the contents of Gly and Cys (sweet amino acids) were significantly elevated under natural light (N) and white light (W) treatments compared to the control (CK). In contrast, the contents of the essential amino acids Ile, Met, and Val were generally suppressed across most light treatments, with pink light (P), green light (G), and red light (R) causing the most substantial reductions.

Regarding the overall taste profile, red light (R) and natural light (N) treatments were conducive to improving flavor, as evidenced by a decreased proportion of bitter amino acids (BAA/TAA) and an increased proportion of umami and sweet amino acids [(UAA + SAA)/TAA] (Table 4). It is worth noting that Val is classified as a bitter amino acid, and its suppression under these light conditions aligns with the observed improvement in flavor profile.

The functional components of S. commune include polysaccharides, phenolic compounds, flavonoids, among others, with primary analysis focused on polysaccharide content. As shown in Figure 5, the polysaccharide content of S. commune varied under different light stresses. The highest polysaccharide content was observed under pink light treatment, which increased by 10.15% (p < 0.05) compared to the dark treatment. The polysaccharide content under yellow light treatment was the second highest, showing a 5.13% (p < 0.05) increase compared to the dark treatment. In contrast, the polysaccharide contents under natural light, white light, blue light, and dark treatments were relatively low. These results indicate that pink light and yellow light treatments are more conducive to the accumulation of polysaccharides in S. commune, whereas white light and blue light qualities had the opposite effect.

This might be due to the differential activation of the photoreceptor system and downstream metabolic pathways. Pink light, as a broad-spectrum light with a peak in the red region, might synergistically activate both red- and blue-light sensing pathways, potentially leading to a unique transcriptional reprogramming that favors the allocation of carbon precursors towards polysaccharide biosynthesis (23). On the other hand, the stimulatory effect of yellow light, which is often poorly absorbed by typical fungal photoreceptors, could be an indirect stress response. Sub-optimal light signals might trigger a defense or storage response in the fungus, channeling resources into the synthesis of protective or reserve compounds like polysaccharides (24). Conversely, white light and blue light may prioritize other metabolic processes at the expense of polysaccharide accumulation, explaining its lower yields here (25).

The nutritional components of S. commune include protein, cellulose, lipids, carbohydrates, etc. The analysis mainly focuses on the protein composition, cellulose composition, and lipid composition.

As shown in Figure 6a, significant differences were observed in the protein content of S. commune under different light stresses. Among them, the protein content of S. commune under pink light treatment was the highest, which increased by 35.25% compared with the dark treatment, followed by that under natural light treatment, which increased by 26.75% (p < 0.05) compared with the dark treatment. In contrast, the protein content of S. commune under white light treatment was the lowest. Overall, different light stresses significantly affected the protein content, with pink light treatment being more conducive to the increase of protein content in S. commune, while white light showed the opposite effect.

As shown in Figure 6b, regarding the cellulose content, the highest cellulose content in S. commune was observed under pink light treatment, which increased by 19.87% compared with the dark treatment, followed by that under green light treatment, which increased by 8.63% (p < 0.05) compared with the dark treatment. In contrast, the cellulose content of S. commune under natural light treatment was the lowest. Overall, different light qualities significantly affected the cellulose content, with pink light treatment being more conducive to the increase of cellulose content in S. commune, while natural light showed the opposite effect.

In terms of lipid content, as shown in Figure 6c, there are significant differences in lipid content under different light stresses. Among them, S. commune under red light treatment exhibited the highest lipid content, followed by S. commune under natural light treatment, while S. commune under dark treatment showed the lowest lipid content. Overall, different light stresses had a significant impact on lipid content, with red light being more conducive to increasing lipid content, whereas the dark environment had the opposite effect.

As shown in Figure 7, OPLS-DA analysis was conducted with 17 free amino acids and 4 internal components as dependent variables and different light stresses as independent variables. The fitting indices for the independent variable (R₂ ^x ), the dependent variable (R₂ ^y ), and the model prediction index (Q²) in this analysis were 0.998, 0.98, and 0.87, respectively. Both R² and Q² exceeded 0.5 and were close to 1, indicating a good model fit (26, 27). As shown in Figure 7a, the data points within groups were concentrated, while those between groups were scattered, demonstrating that the experimental methods and instruments were reliable and stable. Therefore, the contents of amino acids and internal components could be used as indicators for sensitivity analysis of S. commune to different light stresses. As shown in Figure 7b, a VIP value >1 indicates that the variable contributes significantly to the model and may be a key indicator for analyzing differences (28). Crucially, the variable importance in projection (VIP) plot identified five amino acids with VIP scores greater than 1: isoleucine (Ile), lipid, cysteine (Cys), methionine (Met), glycine (Gly). These compounds are thus the most significant contributors to the metabolic differences observed under various light qualities. Simultaneously, to verify whether the OPLS-DA model was overfitted, resulting in Figure 7c. The results showed that the intersection point of the Q² regression line and the vertical axis was less than 0, and both R² (0.27) and Q² (−1.73) were below the retention value of 1.0, confirming the absence of overfitting and the validity of the model validation (29).

The prominence of these amino acids suggests a specific metabolic response in S. commune. For instance, glutamic and aspartic acids are pivotal umami-tasting amino acids; their variation indicates that light stress can significantly alter the flavor profile of the fungus. Meanwhile, the changes in alanine and arginine may reflect alterations in nitrogen metabolism and energy regulation.