Abstract: Two problems of metabolic control analysis are the acquisition of enzyme activity distribution and the calculation of flux control coefficient (FCC), which often needs gene manipulation and complicated calculation. A large number studies indicated that both quantitative trait loci (QTL) effect and flux control coefficient revealed similar L-shaped distribution. Therefore, metabolic flux of β-carotene in spirulina was considered as a quantitative trait. Principal component analysis and path analysis were used to explore the control effects of enzymes on metabolic flux for the first time. The control coefficients based on principal component analysis (Cpi) and path analysis (R2i) were established after correlation analysis between enzymes and metabolic flux. Comparative analysis results indicated control coefficients from both groups had a consistent change trend. Therefore, five enzymes including lycopene β-cyclase (LYC-B, CpLYC-B = 0.161, R2LYC-B = 0.2601), ribulose-1,5-bisphosphate carboxylase (RuBisCO, CpRuBisCO = 0.121, R2RuBisCO = 0.2453), phosphoglyceromutase (PGM, CpPGM = 0.163, R2PGM = 0.2320), pyruvate dehydrogenase (PDHC, CpPDHC = 0.119, R2PDHC = 0.1584) and isocitrate dehydrogenase (ICDH, CpICDH = 0.172, R2ICDH = 0.1935) played an important role in the flux of β-carotene. The two established methods in this study are simple and accurate so that these methods with simplified operation and calculation process will provide new strategies for metabolic engineering breeding and metabolic control analysis.

Key words: quantitative genetics, metabolic control analysis, principal component analysis, path analysis, β-carotene