Breeding for color development.

BREEDING FOR COLOR DEVELOPMENT OF HORTICULTURAL CROPS

IAGS, New Campus, Lahore

PIGMENTS

• Responsible for color and variety

Major plant pigments and their occurrence Pigment Common types Where they are found Examples of

typical colors

chlorophylls chlorophyll Green plants Green

Caretoineds Carotenes and xanthophylls (e.g. astaxanthin)

Vegetables like carrots . Fruits like mangoes etc

Oranges, reds, yellows, pink.

Flavonoids Anthocyanins, aurones, chalcones, flavonols and proanthocyanidins

Produce many colors in flowers . Common in some plants such as berries ,egg plants and citrus fruits . Present in certain teas ,wines and chocolates .

Yellow, red, blue, purple

Betalains Betacyanins and betaxanthins

Flowers and fungi Red to violet, also yellow to orange

Carotenoids

• Precursor of Vitamin A

Betalains

Betacyanin(betanin, isobetanin,

probetanin, and neobetanin)

Betaxanthin(indicaxanthin and

vulgaxanthins)

Red to Violet Yellow to Orange

DISTRIBUTE IN RBC

GENERAL REIPENING

ETHYLENE PRODUCTION

• More CO2 emission• More ethylene production• gene ETR1 and CTR1 keep the fruit ripening genes from activating

until ethylene is made• After ethylene production, ETR1 andCTR1 turn off• It allows a cascade that ultimately turns on other genes that make

various enzymes:• Pectinases to break down cell walls and soften the fruit;• Amylases to convert carbohydrates into simple sugars; • Hydrolases to degrade the chlorophyll content of the fruit

resulting in color change.

External Factors Affecting the Colour of Carrots• 1. Temperatures above and below the optimum) reduce the colour of carrots.

• 2. Spring and summer carrots are often of better colour than autumn and winter.

• 3. Carrots grown on sandy soils and soils high in organic matter have been shown to produce a higher colour than carrots grown on silt loams.

• 4. Excessive watering decreases the colour.

• 5. Reducing the number of daylight hours can reduce the colour.

• 6. Colour is more intense in the older portions of the root. It decreases from the epidermis and centre toward the cambium, and from the top to the bottom.

Properties 0f colours in carrots colours Pigment Properties

Orange Caotene Alpha –carotene.

Reducing cholestrol.Form rhodopsin which need to see in dim light .

yellow xanthophylls and lutene Prevent lung cancer.astherosclerosis

Red lycopene Maintain healthy skinPrevent heart disease and cancer .

White Lack of pigment .only contain phytochemicals

reducing the risk of atherosclerosis

Purple carrot Beta-caroteneanthocyanins

anti inflammatory agents. protect key cell components

Black carrot Anthocyanins,Flavinoids.

anti-bacterial , anti-fungicidal properties. Anti cancer

• In the case of Capsicum, carotenoid-biosynthesis regulation at the gene and enzyme levels is not fully understood. It is well known that the total carotenoid content is quite diverse among Capsicum species (C. baccatum, C. chacoense, C. chinense, C. frutescens and C. annuum)

• Capsicum annuum lines very often exhibit the highest carotenoid content, ranging between 390 and 16,600 μg/g (d.wt.)

• These data suggest that there may be several regulation steps in carotenoid biosynthesis, depending on the genotype

• Fine genetic control of carotenoid production is responsible for the type and quantity of carotenoid accumulation in chili pepper fruits.

• It has been established that mature chili pepper fruit color is determined by three loci (three independent pairs of genes): c1, c2 and y

• Furthermore, using RFLP and specific-PCR to analyze DNA sequences and thus determine polymorphisms for the CCS gene in F2 progeny (this filial was derived from a cross between red and yellow fruit-producing chili pepper plants) showed that CCS completely segregated with the red fruit color and that locus y (encoding for CCS) controlled the red character

• yellow chili pepper fruit color phenotype might be the result of a CCS gene deletion

• CCS determined the chili pepper fruit color by altering the carotenoid pattern

• A genetic map was established using RFLP and AFLP markers and an F2 population derived from an inter specific cross between Capsicum annuum cv. TF68 and Capsicum chinense cv. Habanero, The TF68 ripe fruit was red and its Habanero counterpart was orange.

Future Research on Chili Pepper Carotenoid Biosynthesis

• Not all carotenoid biosynthesis pathways in chili pepper fruits are completely known and understood, and more research is thus needed to elucidate these carotenoid pathways, including those that produce minor carotenoids, at both the enzymatic and genetic levels.

• Unfortunately, the regulation of carotenoid biosynthesis in Capsicum at the gene and enzyme level is currently poorly understood.

• Only a few studies of transcription factors or other genes that impose global regulatory functions on carotenoid metabolism in plants have been described

• Only two types of transcription factors (RAP2.2 and PIFs) have been identified that directly interact with the Arabidospsis PSY promoter.

• No reports of transcription factors that regulate carotenoid biosynthesis in Capsicum have been revealed so far.

• Until now, only the CCS gene promoter has been partially studied, and some cis-element sequences have been reported .

• Characterization of promoter sequences for all of the structural biosynthetic carotenogenic genes should surely reveal possible interactions with transcription factors and also developmental or environmental regulatory elements.

REFRENCES

• http://www.webexhibits.org/causesofcolor/7A.html• http://www.webexhibits.org/causesofcolor/7H.html• http://www.ncbi.nlm.nih.gov/pubmed/15713051• http://www.scientificamerican.com/article/origin-of-fruit-ripen

ing/• http://plantsinaction.science.uq.edu.au/book/export/html/84• http://www.mdpi.com/1422-0067/14/9/19025/htm• http://www.carrotmuseum.co.uk/carrotcolours.html