Engineered native pathways for high kaempferol and caffeoylquinate production in potato.
Flavonols and caffeoylquinates represent important groups of phenolic antioxidants with health-promoting activities. The genetic potential of potato (Solanum tuberosum) to produce high levels of these dietary compounds has not been realized in currently available commodity varieties. In this article, it is demonstrated that tuber-specific expression of the native and slightly modified MYB transcription factor gene StMtf1(M) activates the phenylpropanoid biosynthetic pathway. Compared with untransformed controls, transgenic tubers contained fourfold increased levels of caffeoylquinates, including chlorogenic acid (CGA) (1.80 mg/g dry weight), whilst also accumulating various flavonols and anthocyanins. Subsequent impairment of anthocyanin biosynthesis through silencing of the flavonoid-3',5'-hydroxylase (F3'5'h) gene resulted in the accumulation of kaempferol-rut (KAR) to levels that were approximately 100-fold higher than in controls (0.12 mg/g dry weight). The biochemical changes were associated with increased expression of both the CGA biosynthetic hydroxycinnamoyl-CoA quinate hydroxycinnamoyl transferase (Hqt) gene and the upstream chorismate mutase (Cm) and prephenate dehydratase (Pdh) genes. Field trials indicated that transgenic lines produced similar tuber yields to the original potato variety Bintje. Processed products of these lines retained most of their phenylpropanoids and were indistinguishable from untransformed controls in texture and taste.
Rommens
Caius M
CM
Simplot Plant Sciences, J. R. Simplot Company, Boise, ID 83706, USA. crommens@simplot.com
Richael
Craig M
CM
Yan
Hua
H
Navarre
Duroy A
DA
Ye
Jingsong
J
Krucker
Michele
M
Swords
Kathy
K
D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism; D024322:Amino Acids, Aromatic / Q000378:metabolism; D000872:Anthocyanins / Q000378:metabolism; D017931:DNA Primers; D004789:Enzyme Activation; D044948:Flavonols / Q000378:metabolism; D020869:Gene Expression Profiling; D005818:Genetic Engineering / Q000379:methods; D044949:Kaempferols / Q000096:biosynthesis*; D035281:Plant Tubers / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D011302:Prephenate Dehydratase / Q000235:genetics / Q000378:metabolism; D011801:Quinic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D011198:Solanum tuberosum / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism
D024322:Amino Acids, Aromatic; D000872:Anthocyanins; D017931:DNA Primers; D044948:Flavonols; D044949:Kaempferols; D018749:RNA, Plant; C472707:caffeoylquinic acid; D011801:Quinic Acid; C006552:kaempferol; D000217:Acyltransferases; C021394:hydroxycinnamoyl-CoA-quinate transferase; D011302:Prephenate Dehydratase