Volume 117, September 2015, Pages 267–295
Highlights
- •
- All identified plant betalains are presented with relevant chemical information.
- •
- Computed annual production potential of betalains from plant sources.
- •
- Betalain and anthocyanin-accumulating families under Caryophyllales updated.
- •
- Betalain biosynthesis pathway vis-a-vis their regulation.
Abstract
Betalains
are vacuolar pigments composed of a nitrogenous core structure,
betalamic acid
[4-(2-oxoethylidene)-1,2,3,4-tetrahydropyridine-2,6-dicarboxylic acid].
Betalamic acid condenses with imino compounds (cyclo-l-3,4-dihydroxy-phenylalanine/its
glucosyl derivatives), or amino acids/derivatives to form variety of
betacyanins (violet) and betaxanthins (yellow), respectively. About 75
betalains have been structurally unambiguously identified from plants of
about 17 families (known till date) out of 34 families under the order
Caryophyllales, wherein they serve as chemosystematic markers. In this
review, all the identified betalain structures are presented with
relevant discussion. Also, an estimated annual production potential of
betalains has been computed for the first time. In addition, mutual
exclusiveness of anthocyanins and betalains has been discussed in the
wake of new evidences. An inclusive list of betalain-accumulating plants
reported so far has been presented here to highlight pigment occurrence
and accumulation pattern. Betalain synthesis starts with hydroxylation
of tyrosine to DOPA, and subsequent cleavage of aromatic ring of DOPA
resulting to betalamic acid formation. This pathway consists of two key
enzymes namely, bifunctional tyrosinase (hydroxylation and oxidation)
and DOPA dioxygenase (O2-dependent aromatic ring cleavage).
Various spontaneous cyclisation, condensation and glucosylation steps
complement the extended pathway, which has been presented here
comprehensively. The biosynthesis is affected by various
ecophysiological factors including biotic and abiotic elicitors that can
be manipulated to increase pigment production for commercial scale
extraction. Betalains are completely safe to consume, and contribute to
health.
Graphical abstract
This
review discusses all identified betalains from plant sources with
relevant chemical information for easy reference. Annual production
potential of betalains from plant sources has been computed first time
in this review. Betalain and anthocyanin-accumulating families under
Caryophyllales have been separately compiled. In addition, a
comprehensive pathway for betalain biosynthesis is illustrated vis-a-vis
their regulation.
Keywords
- Betacyanins;
- Betaxanthins;
- Biosynthesis;
- Regulation;
- Ecophysiological factors
Copyright © 2015 Elsevier Ltd. All rights reserved.
Giridhar
Parvatam obtained his Masters degree in Botany in 1991 at the Kakatiya
University Warangal, India. He started his research career in 1992 at
the Department of Botany of the Kakatiya University in the research
group of Professor S. M. Reddy, working in the field of fungal secondary
metabolites. He obtained his Ph.D. in the area of Mycotoxins in May
1996 at the Kakatiya University, Warangal, India, under the supervision
of Prof. S.M. Reddy. The subject of his thesis was the studies on
mycotoxigenic fungi associated with spices and dry fruits. During 1996
to 1996 he had been to University of Bayreuth, Germany on DAAD
Fellowship and worked with plant physiology group under the guidance of
Professor Ewald Komor working in the field of phytoalexins accumulation
and phloem characteristics in Ricinus communis. Subsequently in
1999 he joined as Scientist at Plant Cell Biotechnology Department of
CSIR-Central Food Technological Research Institute, Mysore. After having
switched his research interests towards plant biotechnology, he is
working in the area of tissue culture, in vitro production and
regulation of plant secondary metabolites from food value plants that
includes natural pigments (anthocyanins, betalains, carotenoids),
flavours, caffeine, capsaicin, steviosides, isoflavones etc, along with
the development of novel and eco-friendly methodologies for augmentation
of annatto dye. In 2005 he was awarded DST-BOYSCAST Fellowship of
Government of India. As a part of this program he was associated with
Coffee genomics group of Dr. Alexandre de Kochko at the Institute for
Research and Development, Montpellier, France for one year. In September
2010 he became Principal Scientist at CSIR-CFTRI, Mysore, and his work
is currently concerned with the metabolic engineering of secondary
metabolites from plants. He is currently author of 130 peer-reviewed
publications, 5 reviews, 3 chapters in books, 10 Indian patents and one
US and EU patent, and has presented several invited lectures, oral and
poster communications at national and international Conferences. Dr.
Giridhar has h-index, 19 and i10-index, 40. He is a
recipient of Young scientist award of Academy of Plant Sciences India in
2003, Prof. Y.S. Murthy Young Botanist Award of Indian Botanical
Society in 2007, Prof. H.C. Dube Outstanding Young Scientist Award of
Indian Society of Mycology and Plant Pathology in 2008, Best Research
Scientist Award of CSIR-CFTRI in 2012, Laljee Godhoo young Food
technologist Award of Association of Food Scientists and Technologists,
India in 2012. He is an elected member of National Academy of Sciences,
Allahabad, India in 2008 and Plant Tissue Culture Association of India
in 2009. He is bestowed with Fellowship of Academy of Plant Sciences,
India (2008), Indian Botanical Society (2009), and Society for Applied
Biotechnology, India (2011).
