TY - JOUR
T1 - Proanthocyanidin synthesis in Theobroma cacao
T2 - Genes encoding anthocyanidin synthase, anthocyanidin reductase, and leucoanthocyanidin reductase
AU - Liu, Yi
AU - Shi, Zi
AU - Maximova, Siela
AU - Payne, Mark J.
AU - Guiltinan, Mark J.
N1 - Funding Information:
We thank Yongzhe Pang and Richard A. Dixon from Samuel Roberts Noble Foundation for valuable contribution on the TcLAR protein purification and enzyme assay, Dennis Arocena for assistance with PA and anthocyanin extraction, Dr. David Stuart and the scientists and staff from Hershey Center for Health and Nutrition for discussions and support through providing access to Hershey Technical Center HPLC facility, Ann Young and Sharon Pishak for assistance with green house maintenance, tissue culture and cacao sample collection, Kabing Xie and Qin Wang for valuable technical suggestions on TcLAR recombinant protein expression. This work is supported in part by the Hershey Foods Corporation, The Pennsylvania State University, The Huck Institutes of Life Sciences and American Research Institute Penn State Endowed Program in the Molecular Biology of Cacao.
PY - 2013/12/5
Y1 - 2013/12/5
N2 - Background: The proanthocyanidins (PAs), a subgroup of flavonoids, accumulate to levels of approximately 10% total dry weight of cacao seeds. PAs have been associated with human health benefits and also play important roles in pest and disease defense throughout the plant.Results: To dissect the genetic basis of PA biosynthetic pathway in cacao (Theobroma cacao), we have isolated three genes encoding key PA synthesis enzymes, anthocyanidin synthase (ANS), anthocyanidin reductase (ANR) and leucoanthocyanidin reductase (LAR). We measured the expression levels of TcANR, TcANS and TcLAR and PA content in cacao leaves, flowers, pod exocarp and seeds. In all tissues examined, all three genes were abundantly expressed and well correlated with PA accumulation levels, suggesting their active roles in PA synthesis. Overexpression of TcANR in an Arabidopsis ban mutant complemented the PA deficient phenotype in seeds and resulted in reduced anthocyanidin levels in hypocotyls. Overexpression of TcANS in tobacco resulted in increased content of both anthocyanidins and PAs in flower petals. Overexpression of TcANS in an Arabidopsis ldox mutant complemented its PA deficient phenotype in seeds. Recombinant TcLAR protein converted leucoanthocyanidin to catechin in vitro. Transgenic tobacco overexpressing TcLAR had decreased amounts of anthocyanidins and increased PAs. Overexpressing TcLAR in Arabidopsis ldox mutant also resulted in elevated synthesis of not only catechin but also epicatechin.Conclusion: Our results confirm the in vivo function of cacao ANS and ANR predicted based on sequence homology to previously characterized enzymes from other species. In addition, our results provide a clear functional analysis of a LAR gene in vivo.
AB - Background: The proanthocyanidins (PAs), a subgroup of flavonoids, accumulate to levels of approximately 10% total dry weight of cacao seeds. PAs have been associated with human health benefits and also play important roles in pest and disease defense throughout the plant.Results: To dissect the genetic basis of PA biosynthetic pathway in cacao (Theobroma cacao), we have isolated three genes encoding key PA synthesis enzymes, anthocyanidin synthase (ANS), anthocyanidin reductase (ANR) and leucoanthocyanidin reductase (LAR). We measured the expression levels of TcANR, TcANS and TcLAR and PA content in cacao leaves, flowers, pod exocarp and seeds. In all tissues examined, all three genes were abundantly expressed and well correlated with PA accumulation levels, suggesting their active roles in PA synthesis. Overexpression of TcANR in an Arabidopsis ban mutant complemented the PA deficient phenotype in seeds and resulted in reduced anthocyanidin levels in hypocotyls. Overexpression of TcANS in tobacco resulted in increased content of both anthocyanidins and PAs in flower petals. Overexpression of TcANS in an Arabidopsis ldox mutant complemented its PA deficient phenotype in seeds. Recombinant TcLAR protein converted leucoanthocyanidin to catechin in vitro. Transgenic tobacco overexpressing TcLAR had decreased amounts of anthocyanidins and increased PAs. Overexpressing TcLAR in Arabidopsis ldox mutant also resulted in elevated synthesis of not only catechin but also epicatechin.Conclusion: Our results confirm the in vivo function of cacao ANS and ANR predicted based on sequence homology to previously characterized enzymes from other species. In addition, our results provide a clear functional analysis of a LAR gene in vivo.
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U2 - 10.1186/1471-2229-13-202
DO - 10.1186/1471-2229-13-202
M3 - Article
C2 - 24308601
AN - SCOPUS:84889050826
SN - 1471-2229
VL - 13
JO - BMC plant biology
JF - BMC plant biology
IS - 1
M1 - 202
ER -