|Payyavula, Raja - Washington State University|
|Navarre, Duroy - Roy|
|Shakya, Roshani - Washington State University|
|Sengoda, Venkat - Former ARS Employee|
|Munyaneza, Joseph - Joe|
|Swamy, Prashant - University Of Georgia|
Submitted to: Plant Biotechnology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2014
Publication Date: 4/23/2015
Citation: Payyavula, R., Navarre, D.A., Shakya, R., Sengoda, V., Munyaneza, J.E., Swamy, P. 2015. Synthesis and regulation of chlorogenic acid in potato: Rerouting phenylpropanoid flux in HQT silenced lines. Plant Biotechnology Journal. 13:551-564.
Interpretive Summary: Potato phenylpropanoids have important roles in both plants and humans. In plants they have diverse roles including abiotic stress resistance, development, flowering, pest and pathogen resistance. They are also dietarily desirable with a range of health-promoting effects. This work further clarifies the role of potato phenylpropanoids and shows how the most abundant tuber phenylpropanoid is regulated and how blocking its production alters the plant profile. This information brings us closer to being able to produce potatoes that have optimal phenylpropanoid profiles for both plant and human health.
Technical Abstract: Chlorogenic acid (CGA) is the major phenolic sink in potato tubers and can constitute over 90% of total phenylpropanoids. The regulation of CGA biosynthesis in potato and the role of the CGA biosynthetic gene hydroxycinnamoyl-CoA:quinate hydroxycinnamoyl transferase (HQT) was characterized. A sucrose induced accumulation of CGA correlated with the increased expression of phenylalanine ammonia-lyase (PAL) rather than HQT. Transient expression of the potato MYB transcription factor StAN1 (Anthocyanin1) in tobacco increased CGA. RNAi suppression of HQT resulted in over a 90% reduction in CGA and resulted in early flowering. The reduction in total phenolics and antioxidant capacity was less than the reduction in CGA, suggesting flux was rerouted into other phenylpropanoids. Network analysis showed distinct patterns in different organs, with anthocyanins and phenolic acids showing negative correlations in leaves and flowers, and positive in tubers. Flavonols showed a trend to decrease in transgenic tubers and leaves, but increase in flowers. Anthocyanins increased in flowers and leaves, but not in tubers. HQT suppression increased biosynthesis of caffeoyl polyamines, some of which are not previously reported in potato. Decreased PAL expression and enzyme activity was observed in HQT suppressed lines, suggesting the existence of a regulatory loop between CGA and PAL. Electrophysiology detected no effect of CGA suppression on potato psyllid feeding. Collectively, this research showed that CGA in potatoes is synthesized through HQT, but is predominately regulated by other factors, such as PAL and AN1.