The Induction of Lycopene in Germinating Cottonseed with 2-(4-Methylphenoxy) Triethylamine (MPTA)

Abstract: Problem Statement: Increasing carotenoids content in foods was currently of great interest. The present paper reports strong stimulatory effect of MPTA on the carotenogenesis in cotton, which was used as a model. Approach: Cotton seedlings were treated with MPTA vs. water and germinated in the dark. The levels of carotenoids were determined by HPLC and the expression levels of the key genes were determined by real-time PCR. Results: In the water treated dark germinating control cotton seedlings only low levels of lutein and β-carotene were detected. Treatment of dark germinating seedlings with substituted triethylamine MPTA resulted in an 88% reduction of lutein and a 100% reduction of β-carotene and nearly 18 fold increases in the total carotenoid production with the increase mainly due to the formation of lycopene and its precursors. Treatment of the germinating cottonseed with MPTA and antibiotics such as actinomycin-D, α-amanitin, cordycepin or cycloheximide reduced the stimulatory effect of MPTA. This indicates that increased biosynthesis of carotenes with MPTA was dependent on gene expression, polyadenylation of the gene transcripts and translation of the mRNA on 80S ribosomes. In addition, the relative transcript levels of phytoene synthase, psy1 and psy2 in the MPTA germinating seedlings increased 6.5 and 2.2 fold, respectively, compared to the transcript levels in the H₂O controls. The relative levels of lyc-β and lyc-ε transcripts in the MPTA treated seed increased 3.7 and 3.6 fold, respectively, compared to the H₂O controls. Conclusion: These results support the conclusion that the accumulation of lycopene and lycopene precursors in the MPTA treated germinating cottonseed was dependent on the partial blockage of LYC-β and LYC-ε and the induced expression and translation of the psy genes leading to an increased carotenogenesis.