diff --git a/assays/qPCR/README.md b/assays/qPCR/README.md
index d648acfa89f3a0839a2ad1edc0668f780a492167..118cad37577532c861cc466d79dcfb7b45f375e7 100644
--- a/assays/qPCR/README.md
+++ b/assays/qPCR/README.md
@@ -8,4 +8,18 @@ Suppl. Table 2.
 
 ### Supplementary Figure 3 source
 
+https://www.frontiersin.org/articles/10.3389/fpls.2023.1024981/full#supplementary-material
+
+### Supplementary Figure 4 caption
+
+**Supplementary Figure 4:** Results of qRT-PCR for genes sqs and dxs as log10-fold changes
+compared to the control strain in the strains *Synechocystis* Δshc pEERM Prha sqs pSHDY rhaS,
+*Synechocystis* Δshc pEERM Prha dxs pSHDY rhaS, respectively. Values were calculated via the
+2−ΔΔCT method, using rpoA as a housekeeping gene and cDNA extracted from *Synechocystis* Δshc
+pSHDY rhaS, treated with the same rhamnose concentration as a control strain. Primer sequences are
+shown in Suppl. Table 2. The mean and standard deviation of two biological replicates is shown,
+which were measured in technical triplicates.
+
+### Supplementary Figure 4 source
+
 https://www.frontiersin.org/articles/10.3389/fpls.2023.1024981/full#supplementary-material
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