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THE role of Carotenoids IN Flower crops

M. SanghamitraPresented by,

Contents: Introduction to pigments Carotenoids and its Distribution Classification Structure Biosynthetic pathway Extraction Functions Carotenoids in flower crops Factors influencing the Carotenoid content in flowers Conclusion

• Pigment is an organic molecule that selectively absorbs light of specific wavelengths.

• They produce the colors that we observe at each step of our lives, because pigments are present in each one of the organisms in the world, and plants are the principal producers.

•They are present in leaves, fruits, vegetables, and flowers , and also present in skin, eyes, and other animal structures and in bacteria and fungi.

INTRODUCTION

Types of pigments:Photosynthetic organs of plants always contain an assortment of

pigments• Chlorophylls• Carotenoids • Phycobilins • Anthocyanins • Betalains

• Flower color is predominantly due to three pigments i.e., Betalains, Carotenoids, and Anthocyanins.• Betalains are least abundant of all the above two pigments and contribute to various hues of ivory, yellow, orange, red and violet.• Anthocyanins contribute to various hues of red, orange, brown and bronze.

CAROTENOIDS

•This is a class of accessory pigments that occur in all photosynthetic organisms, they are especially abundant in yellow-orange Fruits, Vegetables and Flowers.

• Carotenoids absorb light maximally between 460 nm and 550 nm and appear as red, orange, or yellow colors.

• More than 700 naturally occurring Carotenoids have been identified in all plants. In flowers more than 40 Carotenoid pigments have been identified.

Distribution: • Carotenoids are widely distributed in nature. • They are completely hydrophobic (fat soluble) and exist in lipid membranes. They are therefore not located in the vacuoles but in the membrane structures of plastids (exclusively in the chromoplasts of flower petals).• It is a common pigment in the many yellow flowers of the Asteraceae family.• Carotenoids differ from Anthocyanins and betalains in that they play essential roles in plant life, for example photo protective function during photosynthesis and provision of substrates for bio-synthesis of the plant growth regulator ABA.

TYPES OF CAROTENOIDS

Carotenoids are classified by their chemical structure as:

(1) Carotenes that are constituted by carbon and hydrogen. (α -Carotene, β- Carotene, γ -Carotene, Lycopene) (2) Oxycarotenoids or Xanthophylls that have carbon, hydrogen, and, additionally, oxygen.(Lutein, Zeaxanthin, Violoxanthin, β- Cryptoxanthin, Astaxanthin)

Also, carotenoids have been classified as primary or secondary

(1)Primary carotenoids: Those compounds required by plants in photosynthesis (β-carotene, violaxanthin, and neoxanthin)(2) Secondary carotenoids: These are localized in fruits and flowers (-carotene, β-cryptoxanthin, zeaxanthin, antheraxanthin, capsanthin,capsorubin)

Classification

Structure: In general, Carotenoids are compounds comprised of eight Isoprenoid units (ip) with polyene chains that may contain 15 conjugated double bonds whose order is inverted at molecular centre. At one or both ends of the isoprene chain Carotenoids carry an ionone ring.  

β-Carotene(C40H56) , Xanthophyll(C40H56O2)

Xanthophylls contain their oxygen either as hydroxyl groups and/or as pairs of hydrogen atoms that are substituted by oxygen atoms acting as a bridge (epoxide).

Typeof carotenoids

Occurrence

I. Carotenes

-Carotene In many leaves

β-Carotene Major carotene of all plants (carrot, sweet potato)

γ-Carotene Traces in some plants

Lycopene Tomato, Rose hips

II. Xanthophylls

Lutein Major form of Xanthophyll (Marigold, Chrysanthemum)

Zeaxanthin Found in many plants (Safron)

Neoxanthin Found in some plants

Violoxanthin Second major Xanthophyll

β-Cryptoxanthin Found in few species

Astaxanthin Bacteria, Fungi

Flavoxanthin and Auroxanthin

Calendula officinalis

Name of carotenoids Characteristic color

Lycopene Red

- Carotene Yellow

β- Carotene Orange

γ- Carotene Red- orange

Lutein Yellow

Violoxathin Yellow

β- Cryptoxanthin Orange

Zeaxanthin Yellow- orange

Astaxanthin Red

Source: Carotenoids and food preparationWashington, DC, 1997

Carotenoids and its Characteristic color:

Biosynthesis of Carotenoids:

All Carotenoids can be considered as Lycopene derivatives by reactions. The basic skeleton can be modified in many ways including cyclization at one or both ends of the molecule to give different end groups, changes in hydrogenation level, de-hydrogenation and introduction of oxygen containing functional groups, double bond migration, methyl migration, chain elongation, chain shortening or combination of these processes resulting in a great diversity of structures.

Glyceraldehyde 3-Phosphate+ Pyruvate 1-deoxyxylulose 5-Phosphate synthase

1-Deoxyxylulose 5-Phosphate

(3) Isopentenyl- diphosphate+ (1) Dimethylallyl-diphosphate

Geranylgeranyldiphosphate synthase

(2) Geranylgeranyldiphosphate(20 C)

Phytoene synthase

Phytoene (40 C)

1- hydroxy-2-methyl-2-butenyl 4-diphosphate reductase

Phytoene

Phytoene desaturaseZeta-carotene isomerase

Lycopene

Carotene isomeraseZeta-carotene desaturase

ε-Cyclaseβ-Cyclase

β-Cyclaseβ-Cyclase

-Caroteneβ-ring Hydroxylaseε-ring Hydroxylase

β-Carotene

β-carotene hydroxylase

Lutein Zeaxanthin

Violaxanthin

Zeaxanthin epoxidaseβ-Caroten

e

ketolas

e

Astaxanthin

Extraction of total carotenoids:

a.Color: Carotenoids provide colors to flowers, seeds & fruits. Color has an important role in reproduction. Coloration attracts animals that disperse pollen, seeds or spores.

b.The function of carotenoids in photosynthesis: The red, orange and yellow carotenoids function as accessory pigments in photosynthesis. They contribute to photosynthesis by absorbing and transmitting the light energy to chlorophyll and also protect photosynthetic tissues from photo- oxidation.

Functions

c.Xanthophyll cycle:

• In higher plants there are three carotenoid pigments that are active in the xanthophyll cycle violaxanthin, antheraxanthin and zeaxanthin. • During light stress violaxanthin is converted to zeaxanthin via the intermediate antheraxanthin. • This is one of the plant protection mechanisms against light damage. • The number of carotenoid molecules is higher in sun-exposed leaves than darkness maintained leaves. Also, xanthophyll cycle carotenoids (violaxanthin, antheraxanthin, and zeaxanthin) are increased in sun-exposed leaves.

Contud…..

•This phenomenon is very important, sun exposed leaves in a fast-growing stage use not more than 50% of absorbed energy during the stage of maximum radiation (midday), and in some species only 10% is used. • Thus, 50 to 90% of absorbed light is in excess and must be eliminated in order to avoid cellular damage. • Xanthophyll cycle is a process that makes the energy dissipation easy and protects the photosynthetic apparatus.

d. Anti-oxidant:• Carotenoids are also a popular source of antioxidants. Antioxidants protect our body from free radicals. • Free radicals are unstable oxygen molecule, which damage our body cells through destructive oxidation process. • According to studies, several carotenoids are capable of preventing growth of malignant cells. • They can be fighter of lung cancer, breast cancer, prostate cancer and skin cancer. • Researches have shown that if beta-carotene and lycopene is consumed with antioxidant rich vitamins C and E, the adverse side effects of radiation therapy and chemotherapy, used in cancer treatment, can be significantly reduced. • Among the known carotenoids, lycopene is the most powerful antioxidant. Canthaxanthin and astaxanthin show better antioxidant activity than β-carotene or zeaxanthin.

e. Provitamin A:

Carotenoids also play an important role in human nutrition and health, providing provitamin A. Beta-carotene is known as provitamin A, since it is converted into vitamin A in the body. Nearly ten percent of carotenoid present in our food can be converted into vitamin A in the liver and intestine. Besides beta-carotene, alpha carotene and nearly 50 other types of carotenoids can be converted into vitamin A.

f. Macular degeneration:

Lutein and other carotenoids may protect photoreceptors in the retina of the eye from wavelength blue light and help prevent age-related disorders to the eye such as macular degeneration.

• Natural and synthetic carotenoid pigments are used in medicines, clothes, furniture, cosmetics, and in other products.

• A lot of pigments have a well-known pharmacological activity in sickness such as cancer and cardiovascular diseases, and this has stressed pigment importance for human beings.

USES

Additives, colourants:• β-Carotene and other synthetic or natural carotenoids or carotenoid-rich extracts are widely used as additives to colour processed food, drinks, confectionery, ice-cream etc.

•The carotenoids extracted from flower petals are added to poultry feed for intensification of yellow color of egg yolk.

• They are used as dyes for coloring the textiles.

• The carotenes promote the renewal of skin tissue + antibacterial properties prevent infections.

• Carotenoid formation in flowers is associated with the conversion of chloroplasts into chromoplasts.

• Chromoplast formation commences with the disruption of grana thylokoids and disappearance of the chlorophylls.

• In many chloroplasts compartments are formed in place of the grana in which carotenoids are synthesized.

PIGMENT FORMATION

Carotenoids in flower crops: Flowers have been identified that synthesize:

Highly oxygenated carotenoids Principally β carotenes Carotenoids that are species specific ( eg: Eschscholzxanthin in Poppies)

California golden poppy (Eschscholzia californica)

Common name: Marigold Botanical name: Tagetus erecta Family : Asteraceae

•Xanthophylls are the major carotenoid fraction in the flower petals. • Lutein accounts for 80 – 90% of total Xanthophylls content. • Used for poultry feed to intensify the yellow colour of the egg yolk and broiler skin and also for fish.• Also used for colouring food stuffs.

Source: Archives of Biochemistry and Biophysics(2010)

Screening of African marigold (Tagetus erecta L.) cultivars for flower yield and carotenoid pigments.

Chandrashekar Rao et al, (2005)

Case study: 1

Cultivar Days to first flowering

Flower duration(days)

Flower diameter(cm)

Number of flowers

Total caroteniods(mg/g)

Percent petal weight

Pusa Narangi Gainda

97 35 7.7 30.0 2.69 66.4

Orange Double 95 44 13.4 18.3 2.66 87.8

Hyd. Local sel-1 99 23 7.4 32.3 1.07 43.8

Pusa Basanti Gainda

110 38 8.2 17.0 1.37 64.7

African Tall Double Orange

100 31 6.5 25.0 1.87 58.3

Hyd. Local sel-2 102 20 7.1 13.3 0.20 68.6

Hyd. Local sel-3 98 18 5.9 19.0 0.64 48.6

Hyd. Local sel-4 103 21 8.1 7.0 0.32 71.8

Yellow double 109 29 8.5 15.0 0.87 75.3

Lemon yellow 105 25 6.9 11.0 0.55 68.8

Table: Variability in qualitative characters in African marigold cultivars

Common name: ChrysanthemumBotanical name: Chrysanthemum morifolium Family: Asteraceae

• Chrysanthemum is a commercially valuable ornamental plant with bright yellow petals, mainly reflecting the accumulation of lutein.

Source: Archives of Biochemistry and Biophysics(2010)

Common name: Pot marigold Botanical name: Calendula officinalis Family : Asteraceae• The petals and pollen of Calendula officinalis contain the carotenoids flavoxanthin and auroxanthin as antioxidants, & source of their yellow-orange coloration• As a rinse for the hair, pot marigold gives a golden tinge to fair hair.• Petals used to add color to salads , extract is common food additive to produce darker egg yolks.

( Bako et al., 2002)

Common name: Summer pheasant’s eye Botanical name : Adonis aestivalis Family : Ranunculaceae

• It is an ornamental plant native to Europe.•The petals of Adonis aestivalis and A. annua anomalously accumulate a large amount of astaxanthin, resulting in their blood-red color.• Astaxanthin is a ketocarotenoid that is produced in a number of bacteria, fungi and algae. Only a few plant species are known to produce Astaxanthin.

Source: Archives of Biochemistry and Biophysics(2010)

Botanical name :Osmanthus fragrans  Family: Oleaceae

• It is a flower native to China that is valued for its delicate fruity-floral apricot aroma. • The flowers of osmanthus range from silver-white (Osmanthus fragrans Lour. var. latifolius Mak.) to gold-orange (Osmanthus fragrans Lour. var. thunbergii Mak.) to reddish (Osmanthus fragrans Lour. var. aurantiacus Mak.).• Various workers have examined the different colored varieties and find that the gold-orange variety (e.g., Osmanthus fragrans Lour. Var thunbergii ) tends to have more of the desirous notes and tend to be higher in carotenoid derived materials. Among the carotenoids of Osmanthus accumulate beta-Carotene in higher amounts.•The flowers are used to flavour jam, sauce and sweets.

Osmanthus fragrans

Common name: Weld Botanical name: Reseda luteola Family: Resedeceae

Dyer's Rocket or dyer’s broom, is an European plant with long spikes of small, yellowish-green flowers contain carotenoids cultivated as a source of yellow dye. Source: Archives of Biochemistry and Biophysics(2010)

Common name : Dandelion Botanical name: Taraxacum officinale Family: Asteraceae• The flower heads are yellow to orange color.• Analysis have detected the presence of beta- carotene, cryptoxanthin, flavoxanthin and lutein.• Mixed carotenoids can act as cancer preventing anti-oxidants.• With this dandelion flowers we can make a tea that helps muscles to relax.

Common name: Lilies Botanical name: Lilium candidum Family: Liliaceae

• The Asiatic hybrid lily (Lilium spp.) is another commercially valuable ornamental plant with flower colors ranging from red, orange and yellow (carotenoids).Carotenoid profiling has shown that most of the carotenoids in yellow petals are antheraxanthin, violaxanthin and lutein .

Source: Archives of Biochemistry and Biophysics(2010)

Common name: Christamas bells Botanical name: Sandersonia aurentiaca Family: Colchicaceae

The pigments responsible for the golden orange flower color of S. aurantiaca have been characterized and the major carotenoids were zeaxanthin and β-cryptoxanthin

(Neilsen et al., 2003)

Carotenoids in some other flower crops:

Narcissus (β- Carotene, Lutein) Coreopsis

Viola tricolor (Yellow cultivars of Coreopsis and Viola contain carotenoids)

Source:Liedvogel et al., 1976.,Hansmann and Kleinig, 1982

Golden rod Tansy

Source: Archives of Biochemistry and Biophysics(2010)

The flower heads of Golden rod and Tansy contains small amounts of Carotenoids.

Tulips(β –Carotene, Lutein) Oncidium (Violoxanthin)

Source: Archives of Biochemistry and Biophysics (2010)

Effects of Environmental Conditions and Cultivation Practices on carotenoids:

• Environmental conditions and cultivation practices influence Carotenoid content, since it is related to photosynthetic efficiency and density of chloroplasts.

• Heat stress, drought stress, and stress by pollution or salt are detrimental to Carotenoid content, as they effect the plant growth and health in general.

• The age and maturity of plant tissues at harvest is a significant factor leading to apparent variations in Carotenoid concentration.

Hot Weather Increases Carotenoids:

• Carotenoids increase production in response to heat and lots of sun. •The hotter and sunnier the weather gets, the more carotenoids a plant produces, and flower color becomes brighter orange and red.

•When weather cools off, carotenoid production decreases, and colors become softer oranges and yellows.

• It works with Hibiscus. In hot, sunny, summertime heat, Hibiscus is bright red with vivid yellow markings. In cool cloudy weather, hibiscus bloom with soft orange color. Banga and Bruyn noticed synthesis of more carotenes at higher temperature (23°C) than at the low temperature (17° or 10°C).

Bright red with vivid yellow markings Soft orange color

Fertilization enhances the carotenoid content of flowers:

• By application of potassium increases the carotenoid content of flower because ‘K’ play a special role in the process of carotenoid biosynthesis by activating several enzymes participating in biosynthetic pathway as well as the precursors of isopentanyl diphosphate. (Pyruvate and Glyceraldehyde 3 phosphate)

• By application of ‘K’ in the form of sulphate of potash also increases the carotenoid content through supply of sulphur along with potassium from sulphate of potash.(Ananthi et al., 2004)

Fertilization enhances growth, yield, and xanthophyll contents of marigold

Iftikhar et al,(2010)

Case study:2

Light Absorption and Carotenoid Synthesis of Pot Marigold

(Calendula officinalis L.) in Response to Phosphorous and Potassium Varying Levels.

Sedhgi et al, (2011)

Case study:3

P2O5 (kg/ha) K2O (kg/ha) β-Carotene(mg/g)

Biological yield(g/m2)

0 050100150

2.52.83.12.9

360.4385.3489.1495.6

40 050100150

2.63.23.43.9

368.9392.4498.3507.6

80 050100150

2.73.54.14.3

376.1402.1524.6534.2

120 050100150

2.53.53.43.4

411.5510.7548.3552.1

Table: Compaision of means of carotenoids and yield of pot marigold as effected by interaction of K and P

Improvement of the Yield and Essential Oils Quantitative in Calendula (Calendula officinalis L.) by Using Different Planting

Arrangement and Potassium Fertilizer

Hashemabadi et al, (2012)

Case study:4

Treatment Carotenoid( mg/g)

A1 (Square arrangement) 6.68A2 (Lozeng arrangement) 6.58A3 (Rectangular arrangement) 6.20

K1 (Control) 5.79K2 (100 kg /ha) 6.45K3 (200 kg/ha) 6.31K4 (300 kg/ha) 7.38

Table: Effect of plant arrangement , K2SO4 and interaction between plant arrangement and K2SO4 on traits

• Recovery of carotenoids depends on the stage of harvest.• Larger flowers have more carotenoids compared to small and over mature flowers.• As the age of the flower increases there will be degradation of carotenoids.

Recovery of Carotenoids

Recovery of carotenoids and its fractions from marigold flowers asinfluenced by genotype, grading and stage of harvest.

Kanwar et al,( 2008)

Case study: 5

Geno type

Total carotenoid content(mg/100g)

Carotene content (mg/100g)

Harvesting stage

Flower grade Harvesting stage

Flower grade

Half bloom

Full bloom

Small flower

Large flower

Half bloom

Full bloom

Small flower

Large flower

Pusa Narangi Gainda

415.84

385.48

355.77 378.41 25.01 20.72 18.21 23.14

Sel-8 405.19

347.15

308.77 321.72 25.06 20.36 18.45 20.78

Sel-19 397.05

326.75

302.58 319.28 47.13 45.09 41.64 44.37

Sel-20 380.95

312.56

291.43 301.41 21.01 17.45 15.14 19.09

Sel-22 369.83

318.78

295.99 304.97 17.67 14.59 13.73 15.69

Sel-29 366.99

331.05

298.04 319.86 46.77 44.07 42.24 43.89

Table: Total carotenoid and carotene content in different marigold genotypes at different harvesting stages and flower grades

Flavonoid and carotenoid pigments in flower tissue of Sandersonia aurantiaca

David et al, (1997)

Case study: 6

Stage of development Zeaxanthin Cryptoxanthin

1:An immature green bud

0.34 Not detected

4:Flower open but still has green tips

0.79 0.52

7:Mature flower completely orange

1.69 2.54

10:Petals wilting and orange color fading

1.01 1.52

Table: Concentration and content per flower for individual carotenoids in a saponified extract from flowers of Sandersonia at different stages of development.

Conclusion

Flowers accumulates large amount of different carotenoids. Considering the importance of carotenoids for industry, human health and plant development, emphasis has been given to targeted manipulation of carotenoid biosynthesis in flowers. Diet rich in carotenoids represents lower risk for several diseases. By the addition of natural carotenoids to healthy foods, the food products containing carotenoids may become superfluous in the future. Carotenoid engineering is expected to contribute to human health, as carotenoids are important pigments as well as nutrients.

Future trends: • More studies must be carried out to have complete vision of the biosynthesis and regulation of Carotenoids.• The researchers should put an interest in two areas ie., generation of crops with improved characteristics and pigment production at the industrial level and under controlled conditions.•Food technologists should continue affronting the problems of availability and stability of natural pigments in order to replace the synthetic ones.• Carotenoid production by Yeasts, Bacteria and fungi require the development of better biotechnological approaches.