Breeding Vegetables for Breeding Vegetables for Optimum Levels of Optimum Levels of

PhytochemicalsPhytochemicalsKevin CrosbyKevin Crosby

Texas A&M UniversityTexas A&M University

Plant BreedingPlant Breeding

• Application of genetic theory, including molecular biology to develop improved plant cultivars

• Vegetables are high priority crops in Texas and USA- numerous cultivars from diverse breeding programs; $15 billion in USA

A. ANY HUMAN HANDLING OF PLANTS WHICH GENETICALLY ADAPTS THEM TO THE SERVICE OF MEN.

B. THE ART OF SELECTION BASED UPON THE SCIENCE OF GENETICS.

C. EVOLUTION DIRECTED BY THE WILL OF MAN. (Vavilov, 1935)

DefinitionsDefinitions

Wild Types vs. ImprovedWild Types vs. Improved

Foods for HealthFoods for Health

• Elevated levels of flavonoids, carotenoids, ascorbic acid, minerals, pectins

• Traditional plant breeding- exploitation of naturally occurring genes in the germplasm

• Gene mapping and genetic transformation- increased Ca, vitamin C, β-carotene

Pepper PhytochemicalsPepper Phytochemicals

• Peppers are good source of important human health related compounds

• Carotenoids, flavonoids, ascorbic acid, capsaicin

• Great genetic variation within pepper germplasm & at different maturity stages

Dietary Fiber in ½ cup ServingDietary Fiber in ½ cup Serving

Green Peppers- raw 2.4

Hot Red Peppers- raw

19.2

Hot Red Peppers- dried

57.6

Pinto Beans- cooked 9.4

Prunes- dried 3.8

Tomatoes- raw 1.4

Spinach- cooked 7.0

Squash- cooked 3.0

Screening GermplasmScreening Germplasm

• Planted 60 diverse pepper lines at Weslaco and Uvalde

• Harvested green and red mature fruit

• Analyzed Vit C by HPLC for replicated samples

High Vitamin CHigh Vitamin C

• Peproncinis- high at all locations, 557 ppm (green) to 2377 ppm (red)

• Pasilla, Anaheim, Marconi and Ancho also very high at red stage- 1900-2280 ppm

• TAM B36- Tropic Bell, highest at green stage: 600 ppm= 60 mg/100g

TAM Pasilla VRTAM Pasilla VR

Cultivar: B 36 (GR-RD)Vitamin C: 1758-2082 ppmFlavonoid: 6-13 ppm

High High β-β-carotenecarotene

• Highest in red chile/paprika- C127 (2330 µg/100g) 38% RDA, Fidel orange chile (2366)

• Almost none in many wax and hot types

• TMJ2 (1242 µg/100g) > Grande (850)

Cultivar: C 127Vitamin C: 1721 ppmFlavonoid: 45 ppmBeta-Carotene: 23.3 ppm

Habanero Habanero β-β-carotenecarotene

TAM Mild- 760 µg/100g Yucatan- 20 µg/100g

Vitamin C -carotene Cultivar/line (mg·100g-1)x (µg·g-1)x Fruit type

TAM Perlita 45 21.7 az 62.2 az Western shipper- size 15y

TAM Uvalde 15.2 b 57.5 ab Western shipper- size 18

Explorer 12.4 bc 45.0 cde Western shipper- size 15

Cruiser 12.1 bc 36.3 e Western shipper- size 12

Mission 11.9 bc 40.3 de Western shipper- size 15

Green Ice 11.8 bc 4.70 f Honeydew- size 15

TAM Mayan 11.2 bcd 11.5 f Casaba- size 12

Gold Mark 10.8 bcd 41.4 cde Western shipper- size 12

TXC 2015 10.0 bcd 49.8 bc Western shipper- size 12

HMX 9583 9.4 cd 46.0 cd Western shipper- size 12

Valley Gold 9.3 cd 48.5 bcd Western shipper- size 12

Mainpak 9.2 cd 43.5 cde Western shipper- size 12

Pronto 8.0 cd 43.0 cde Western shipper- size 12

TAM Dew Impr. 7.2 cd 4.70 f Honeydew- size 12

Primo 7.0 cd 56.7 ab Western shipper- size 12

zMean separations by LSD, P ≤ 0.05. Values followed by the same letter are not significantly different.ySizes based on number of fruit which fit into a standard melon packing box.xBased on fresh weight.

Fresh fruit vitamin C and beta-carotene contents of melons from Weslaco

Selection ProcessSelection Process

• Choose the best parents for target traits

• Controlled pollinations to create new families

• Selection for traits by combined quality analyses- field and lab

• Backcrossing or inbreeding to fix key genes

Controlled PollinationControlled Pollination

Developing a New MelonDeveloping a New Melon

• Industry wants larger cantaloupes with good flavor and disease resistance

• We had excellent flavor, disease resistance, Vit C, carotene in TAM Uvalde

• So we crossed it with ‘Cruiser’ (very large, high yield but poor flavor, carotenoids)

‘‘Chujuc’ MuskmelonChujuc’ Muskmelon

• Large, round fruit, Sz 9-12

• High yield and resistant to PM

• High in beta-carotene Vitamin C, sugars

Genetic Linkage MappingGenetic Linkage Mapping

• Develop population which segregates for gene(s) of interest

• Carefully measure phenotype of trait for each plant and parents

• Screen DNA for molecular markers which are linked to the trait (gene)

DNA Marker LinkageDNA Marker Linkage

RAPD marker OAC09.900 expressing polymorphism between two DNA bulks from high and low beta-carotene F2 plants. 1 = Sunrise (low parent), 2 = TAM Uvalde (high parent), 3 = DNA bulk from low beta-carotene F2 plants, 4 = DNA bulk from high beta-carotene F2 plants, and 5 = a 100-bp DNA marker ladder.

1 2 3 4 5

OAC09.900

-1500 bp

-600 bp

Figure 5. RAPD marker OAU02.600 expressing polymorphism between two DNA bulks from high and low ascorbic acid F2 plants, and between ‘Dulce’ and TGR1551. 1=’Dulce’, 2=TGR1551, 3=DNA bulk from high ascorbic acid F2 plants, 4=DNA bulk from low ascorbic acid F2 plants, and 5=molecular size marker.

-1500bp

-600bp

-300bp

1 2 3 4 5

OAU02.600

Molecular Markers in PepperMolecular Markers in Pepper

• Family of high flavonoid CA377 x high vitamin C B22

• F2 progeny, F1 progeny, Parents grown in two environments for mature fruit

• Screening with RAPD markers in bulks and genotyping each F2 progeny

• Constructing genetic linkage map

High Antioxidant ParentsHigh Antioxidant Parents

TAES B22 CA 377

F1 Hybrid

-2072bp

-600bp

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 M

-1500bp

-300bp

OL07.2050

OL07.1100

OL07.1500OL07.1700

OL07.800

OL07.480OL07.520

Fig. 1. Segregation of seven RAPD markers in an F2 population derived from the pepper cross of CA 377 x B 22. 1 to 20=F2 plants of the CA 377 x B 22 cross and M=a 100-bp DNA marker ladder.

Current ProgressCurrent Progress

Flavor is CrucialFlavor is Crucial

• Many people complain about tomatoes

• Long shelf life and green harvested fruit just do not taste very good

• Enhancing fresh market consumption and profitability for growers requires change

New Breeding PrioritiesNew Breeding Priorities

• Screen germplasm for best tasting tomato cultivars, lines, landraces

• Cross with TAMU heat-tolerant, disease resistant, high yielding breeding lines

• Developed better tasting, adapted cultivars

Improved Heirloom TypesImproved Heirloom Types

Introgressed virus, fusarium and heat resistance genes; developed more compact plants adapted to staked culture

Flavor Trumps AppearanceFlavor Trumps Appearance

Why Vegetable Genetics?Why Vegetable Genetics?

• Vegetables are excellent source of key human health related phytochemicals

• $15 billion component of US agriculture

• Not all cultivars are equal- flavor and appearance are also crucial