Correction: Mthiyane et al. Integrating Biofertilizers with Organic Fertilizers Enhances Photosynthetic Efficiency and Upregulates Chlorophyll-Related Gene Expression in Rice. Sustainability 2024, 16, 9297

The authors would like to make the following corrections to the published paper [1]. The changes are as follows:

• We added the following unit to “Section 3.3. Photosynthesis”, paragraph 1:

Original version:

For the net photosynthetic rate (An) in Figure 3A, the OF+BF treatment had the highest mean value of 48.23 μmol CO₂ m⁻² s⁻¹, reflecting a 74% increase compared to the control’s mean of 27.68 μmol CO₂ m⁻² s⁻¹. Inorganic fertilizer (IOF) also showed notable improvement with a mean An of 42.86 μmol CO₂ m⁻² s⁻¹, representing a 55% increase over the control. The biofertilizer (BF) treatment showed more moderate improvements, with a mean of 29.10 CO₂ m⁻² s⁻¹.

Replaced with:

For the net photosynthetic rate (An) in Figure 3A, the OF+BF treatment had the highest mean value of 48.23 μmol CO₂ m⁻² s⁻¹, reflecting a 74% increase compared to the control’s mean of 27.68 μmol CO₂ m⁻² s⁻¹. Inorganic fertilizer (IOF) also showed notable improvement, with a mean An value of 42.86 μmol CO₂ m⁻² s⁻¹, representing a 55% increase over the control. The biofertilizer (BF) treatment showed more moderate improvements, with a mean of 29.10 µmol CO₂ m⁻² s⁻¹.

2.

We added a number to “Section 3.4. Principal Component Analysis (PCA) Highlights Differences in Fertilizer Treatments, paragraph 2” as follows:

Original version:

On the opposite side, IOF is isolated at 3.5 units on the Dim1 axis and -.0 units on the Dim2 axis.

Replaced with:

On the opposite side, IOF is isolated, with 3.5 units on the Dim1 axis and −1.0 units on the Dim2 axis.

3.

We replaced highlighted words in “Section 3.5. Gene Expression, paragraphs 1–3” as follows:

We replaced the original version, as follows:

Figure 5A displays the expression of OsChl, a gene involved in chlorophyll synthesis. The inorganic fertilizer (IOF) treatment exhibited the highest expression level, with a mean value of 0.083 units, representing a 45% increase compared to the control (CNT, mean value 0.046 units). The rice straw (RS) treatment also increased moderately, showing a 32% rise over the control. In contrast, the biofertilizer (BF) and deactivated biofertilizer (DA BF) treatments led to lower expression levels, with reductions of 24% and 15%, respectively, compared to the control. Figure 5B illustrates the expression of OsChlD, a gene involved in chlorophyll metabolism. The highest expression level was observed in the organic fertilizer combined with biofertilizer (OF+BF) treatment, with a mean value of 0.0011 units, showing a 70% increase over the control (0.0006 units). This indicates that OF+BF significantly enhances chlorophyll biosynthesis. IOF and BF also showed increases, though to a lesser extent, while RS and DA BF exhibited much lower expression levels, suggesting a reduced impact on this gene. Figure 5C highlights the expression of OsChlG, a gene that plays a role in forming chlorophyll-protein complexes. The IOF treatment recorded the highest expression, with a mean value of 0.065 units, indicating a 55% increase compared to the control (0.042 units). The OF+BF treatment also significantly increased OsChlG expression, showing its effectiveness in enhancing the synthesis of chlorophyll-protein complexes essential for photosynthesis.

In contrast, the RS treatment demonstrated the lowest expression levels, indicating a minimal effect on this process. Figure 5D presents the expression of OsCHLM, a gene associated with the methylation of chlorophyll. Again, IOF treatment showed the highest expression level, with a mean of 0.0094 units, representing a 70% increase over the control (CNT). OF+BF also substantially increased OsCHLM expression, underscoring its positive influence on the chlorophyll biosynthesis pathway. However, DA-BF and RS treatments had lower expression levels, indicating a lesser capacity to enhance the methylation process. Figure 5E focuses on the expression of OsPorB, a gene involved in chlorophyll biosynthesis under low-light conditions. The OF+BF treatment yielded the highest expression level, with a mean value of 0.033 units, marking a 90% increase compared to the control (0.017 units). IOF and BF also showed moderate increases in OsPorB expression. At the same time, DA BF and RS treatments exhibited much lower levels, indicating reduced effectiveness in promoting chlorophyll biosynthesis under variable light conditions. Figure 5F shows the expression of OsCAO1, a gene responsible for converting chlorophyll a to chlorophyll b. The OF+BF treatment again demonstrated the highest expression, with a mean value of 0.0025 units, representing a 75% increase compared to the control (0.0014 units). IOF and BF treatments exhibited moderate increases, while RS and DA BF showed significantly lower expression levels, highlighting their limited role in enhancing the conversion of chlorophyll types required for efficient light absorption.

Figure 6A shows the expression of OsTLP27, a gene involved in leaf expansion and photosynthesis. The control (CNT) had the highest expression level, with values around 2.4 relative expression units, significantly higher than all other treatments. Deactivated biofertilizer (DA BF) also showed a relatively high expression level, approximately 2.1 units, close to the control. In contrast, treatments like rice straw (RS), organic fertilizer (OF), inorganic fertilizer (IOF), biofertilizer (BF), rice straw with biofertilizer (RS+BF), and organic fertilizer with biofertilizer (OF+BF) showed significantly lower expression levels, all below 0.4 units, representing an 83% decrease compared to the control, indicating minimal impact on OsTLP27 expression. Figure 6B displays the expression of OsGLK2, a gene regulating chloroplast development. The highest expression was recorded in DA BF, with approximately 0.055 units, while RS showed a moderate increase of about 0.030 units. This was 45% lower than DA-BF but significantly higher than the other treatments. CNT, OF, IOF, BF, RS+BF, and OF+BF exhibited lower expression levels, ranging from 0.010 to 0.020 units, showing an 82% to 64% reduction compared to DA BF, indicating that these treatments had a lesser effect on OsGLK2 expression. Figure 6C highlights the expression of OsDGP1, a gene linked to photosynthetic protein accumulation. The highest expression was seen in DA BF, with values around 0.350 units, significantly higher than all other treatments. RS also showed increased expression, approximately 0.250 units, representing a 28% decrease compared to DA BF. The different treatments, including CNT, OF, IOF, BF, and RS+BF, exhibited lower expression levels, ranging from 0.100 to 0.200 units, showing a 71% to 43% reduction compared to DA BF. OF+BF had the lowest expression at around 0.080 units, reflecting a 77% decrease compared to the highest value. Figure 6D presents the expression of OsαCA1, a gene involved in carbon fixation. BF led to the highest expression, approximately 0.060 units, with IOF showing a relatively high expression at around 0.050 units, about 16% lower than BF. RS+BF and DA BF exhibited moderate expression levels, approximately 0.030 units, representing a 50% reduction compared to BF. In contrast, CNT, RS, OF, and OF+BF had lower expression levels, all below 0.020 units, reflecting a 66% to 75% decrease compared to the highest expression seen in BF. Figure 6E shows the expression of OsLHCB3, a gene involved in light-harvest complex formation. DA BF had the highest expression level, approximately 0.0055 units, significantly higher than all other treatments. CNT and RS also showed moderate expression levels, around 0.0040 to 0.0045 units, a 27% to 18% decrease compared to DA BF. The remaining treatments, including OF, IOF, BF, RS+BF, and OF+BF, exhibited lower expression levels, all below 0.0020 units, reflecting a 64% to 82% decrease compared to DA BF. Figure 6F presents the expression of OsV14, a gene involved in stress response and chloroplast development. DA BF again showed the highest expression level, around 0.045 units, with BF also resulting in increased expression at approximately 0.040 units, showing an 11% reduction compared to DA BF. OF showed moderate expression of about 0.035 units, about 22% lower than the highest expression in DA BF. CNT, RS, IOF, RS+BF, and OF+BF exhibited lower expression levels, ranging from 0.015 to 0.025 units, representing a 44% to 66% decrease compared to DA BF.

With the following version:

Figure 5A displays the expression of OsChl, a gene involved in chlorophyll synthesis. The rice straw (RS) treatment exhibited the highest expression level, with a mean value of 0.031 units, representing a 7.8-fold increase compared to the control (CNT, mean value 0.004 units). The organic fertilizer (OF) treatment also increased, showing 7.1-fold rise over the control. In contrast, the inorganic fertilizer (IOF) and biofertilizer (BF) treatments led to lower expression levels, with reductions to 11% and 42%, respectively, compared to the control. Figure 5B illustrates the expression of OsChlD, a gene involved in chlorophyll metabolism. The highest expression level was observed in the organic fertilizer combined with biofertilizer (OF+BF) treatment, with a mean value of 0.0011 units, showing a 4.4-fold increase over the control (0.00025 units). This indicates that OF+BF significantly enhances chlorophyll formation via OsChlD. RS+BF also showed increases, although to a lesser extent, while RS, OF, and BF alone exhibited much lower expression levels, suggesting a reduced impact on this gene. Figure 5C highlights the expression of OsChlG, a gene that plays a role in forming chlorophyll–protein complexes. The CNT condition resulted in the highest expression, and the OF and deactivated biofertilizer (DA BF) treatments also resulted in a significant OsChlG expression. The OF+BF treatment exhibited a weak expression, with a mean value of 0.005 units, indicating a level that reached only 8% of the control (0.063 units). Thus, the formation of chlorophyll–protein complexes via OsChlG is not involved in the accumulation of chlorophyll resulting from the OF+BF treatment. Figure 5D presents the expression of OsCHLM, a gene associated with the methylation of chlorophyll. The RS+BF treatment showed the highest expression level, with a mean of 0.033 units, representing a 4.8-fold increase over the control. OF+BF similarly increased the OsCHLM expression, underscoring its positive influence on the chlorophyll biosynthesis pathway. However, RS, OF, and DA BF treatments exhibited lower expression levels, indicating a lesser capacity to enhance the methylation process. Figure 5E focuses on the expression of OsPorB, a gene involved in chlorophyll biosynthesis under low-light conditions. The CNT condition yielded the highest expression level, with a mean value of 0.033 units. DA BF also showed a moderate expression of OsPorB (0.009 units). At the same time, the BF, RS+BF, and OF+BF treatments exhibited much lower levels, indicating that the BF treatments do not affect chlorophyll biosynthesis through OsPorB. Figure 5F shows the expression of OsCAO1, a gene responsible for converting chlorophyll a to chlorophyll b. The OF treatment demonstrated the highest expression, with a mean value of 0.184 units, representing a 6.1-fold increase compared to the control (0.030 units). The RS and DA BF treatments exhibited moderate increases, while BF, RS+BF, and OF+BF showed significantly lower expression levels, highlighting their limited role in enhancing the conversion of chlorophyll types required for efficient light absorption.

Figure 6A shows the expression of OsTLP27, a gene involved in leaf expansion and photosynthesis. The CNT condition exhibited the highest expression level, with values of around 1.66 relative expression units, which is significantly higher than all other treatments. DA BF also showed a relatively high expression level of approximately 1.42 units, which is similar to that of the control. In contrast, treatments like RS, OF, IOF, BF, RS+BF, and OF+BF showed significantly lower expression levels, all of which were below 0.02 units, indicating minimal impact on OsTLP27 expression. Figure 6B displays the expression of OsGLK2, a gene regulating chloroplast development. The highest expression was recorded for DA BF, with 0.0452 units, while RS showed a slight increase of about 0.0295 units. This was 45% lower than that of DA BF but significantly higher than those of the other treatments. OF, IOF, BF, RS+BF, and OF+BF exhibited lower expression levels compared to the control (0.0280 units), ranging from 0.0007 to 0.0125 units, indicating that these treatments had a lesser effect on OsGLK2 expression. Figure 6C highlights the expression of OsDGP1, a gene linked to photosynthetic protein accumulation. The highest expression was seen for DA BF, with a value of around 0.313 units, which was significantly higher than those of all other treatments. The different treatments, including RS, OF, IOF, BF, and RS+BF, exhibited lower expression levels compared to the control (0.0199 units), ranging from 0.013 to 0.184 units. IOF exhibited the lowest expression level, reflecting a 96% decrease compared to the highest value. Figure 6D presents the expression of OsαCA1, a gene involved in carbon fixation. DA BF exhibited the highest expression level of approximately 0.0553 units, which was significantly higher than those of all other treatments. The remaining treatments, including RS, OF, IOF, BF, RS+BF, and OF+BF, exhibited lower expression levels, reflecting a 28% to 85% decrease compared to the control (0.0482 units). Figure 6E shows the expression of OsLHCB3, a gene involved in light-harvesting complex formation. The CNT condition led to the highest expression level of approximately 0.00022 units, which was significantly higher than those of all other treatments. The treatments of RS, OF, IOF, BF, RS+BF, and OF+BF exhibited lower expression levels, reflecting a 73% to 97% decrease compared to the control. Figure 6F presents the expression of OsV14, a gene involved in the stress response and chloroplast development. RS+BF showed the highest expression level of about 0.0145 units, and OF+BF also resulted in a high expression level of 0.0076 units. BF exhibited a moderate expression level of 0.0046 units, which was about 68% lower than the highest expression. CNT, RS, OF, and DABF exhibited very low expression levels, which were below the detection limit.

4.

We added a word to the Figure 5 and Figure 6 descriptions in “Section 3.5. Gene Expression” as follows:

Original version:

Figure 5. Biofertilizer combined with organic fertilizer increased the expression levels of key chlorophyll-related genes in rice: (A) OsChl, (B) OsChlD, (C) OsCHLG, (D) OsCHLM, (E) OsPorB, and (F) OsCAO1 under control (CNT), rice straw (RS), organic fertilizer (OF), inorganic fertilizer, biofertilizer (BF), deactivated biofertilizer (DA BF), rice straw + biofertilizer (RS+BF), organic fertilizer + biofertilizer (OF+BF). RGE-Relative Gene Expression for the expression levels of a target gene relative to a housekeeping gene. Error bars represent ±SD (n = 3). Values with the same letter are not statistically different among all treatments (Tukey HSD test, p < 0.05).

Figure 6. Biofertilizer combined with organic fertilizer increased the expression levels of six key genes related to photosynthesis and chloroplast development in rice: (A) OsTLP27, (B) OsGLK2, (C) OsDGP1, (D) OsαCA1, (E) OsLHCB3, and (F) OsV14 under control (CNT), rice straw (RS), organic fertilizer (OF), inorganic fertilizer (IOF), biofertilizer (BF), deactivated biofertilizer (DA BF), rice straw + biofertilizer (RS+BF), organic fertilizer + biofertilizer (OF+BF). RGE: Relative Gene Expression for the expression levels of a target gene relative to a housekeeping gene. Error bars represent ±SD (n = 3). Values with the same letter are not statistically different (Tukey HSD test, p < 0.05).

Replaced with:

Figure 5. Biofertilizer combined with organic fertilizer increased the expression levels of key chlorophyll-related genes in rice: gene expression levels of (A) OsChl, (B) OsChlD, (C) OsCHLG, (D) OsCHLM, (E) OsPorB, and (F) OsCAO1 under control (CNT), rice straw (RS), organic fertilizer (OF), inorganic fertilizer, biofertilizer (BF), deactivated biofertilizer (DA BF), rice straw + biofertilizer (RS+BF), and organic fertilizer + biofertilizer (OF+BF) conditions. RGE: Relative Gene Expression for the expression levels of a target gene relative to a housekeeping gene. Error bars represent ±SD (n = 3). Values indicated by the same letter are not statistically different among all treatments (Tukey’s HSD test, p < 0.05).

Figure 6. Biofertilizer combined with organic fertilizer increased the expression levels of six key genes related to photosynthesis and chloroplast development in rice: gene expression levels of (A) OsTLP27, (B) OsGLK2, (C) OsDGP1, (D) OsαCA1, (E) OsLHCB3, and (F) OsV14 under control (CNT), rice straw (RS), organic fertilizer (OF), inorganic fertilizer (IOF), biofertilizer (BF), deactivated biofertilizer (DA BF), rice straw + biofertilizer (RS+BF), and organic fertilizer + biofertilizer (OF+BF) conditions. RGE: Relative Gene Expression for the expression levels of a target gene relative to a housekeeping gene. Error bars represent ±SD (n = 3). Values indicated by the same letter are not statistically different (Tukey’s HSD test, p < 0.05).

5.

We replaced a word in “Section 4.3. Chlorophyll-Related Gene Expression, paragraph 1” as follows:

Original version:

The expression analysis of chlorophyll-related genes reveals significant variations across different fertilizer treatments. The combination of organic fertilizer and biofertilizer (OF+BF) notably affected key genes involved in chlorophyll biosynthesis and regulation. The OF+BF treatment led to an upregulation of OsChlD and OsCHLM, critical for chlorophyll synthesis and photoperiod-regulated production (Figure 5A,D). Specifically, the OF+BF treatment showed a 70% increase in OsChlD expression and a 55% increase in OsCHLM compared to the control.

Replaced with:

The expression analysis of chlorophyll-related genes reveals significant variations across different fertilizer treatments. The combination of organic fertilizer and biofertilizer (OF+BF) notably affected the key genes involved in chlorophyll biosynthesis and regulation. The OF+BF treatment led to an upregulation of OsChlD and OsCHLM, which are critical for chlorophyll synthesis and photoperiod-regulated production (Figure 5A,D). Specifically, the OF+BF treatment showed a 4.4-fold increase in OsChlD expression and a 4.6-fold increase in OsCHLM expression compared to the control.

6.

We replaced and added words in “Section 4.3. Chlorophyll-Related Gene Expression, paragraphs 2–4” as follows:

Original version:

OsChl expression decreased by 24% and OsCHLG by 15% in the OF+BF treatment relative to the control (Figure 5B,C).

Replaced with:

OsChl expression decreased by 54%, and OsCHLG decreased by 92% in the OF+BF treatment relative to the control (Figure 5A,C).

Original version:

Its expression decreased by 34% under OF+BF treatment compared to the control (Figure 5E). This reduction might indicate that increased chlorophyll levels suppress further gene expression, preventing oxidative stress [75].

Replaced with:

Its expression decreased by 5% under OF+BF treatment conditions compared to the control (Figure 5E). This reduction might indicate that increased chlorophyll levels suppress further gene expression, preventing oxidative stress [75].

Original version:

The lack of microbial activity in the DABF treatment likely impairs nutrient cycling, particularly nitrogen and magnesium essential for chlorophyll biosynthesis, leading to reduced gene expression. OsChl expression in DABF decreased by 39%, emphasizing the importance of maintaining a healthy soil microbiome.

Replaced with:

The lack of microbial activity in the DABF treatment likely impairs nutrient cycling, particularly nitrogen and magnesium, which are essential for chlorophyll biosynthesis, leading to reduced gene expression. OsChl expression in DABF decreased by 56% compared to that in OF, emphasizing the importance of maintaining a healthy soil microbiome.

The authors state that the scientific conclusions are unaffected. This correction was approved by the Academic Editor. The original publication has also been updated.