Breeding Vegetables for Optimum Levels of Phytochemicals Kevin Crosby Texas A&M University

Plant 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) Definitions

Wild Types vs. Improved

Foods 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 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 Serving Green Peppers- raw2.4 Hot Red Peppers- raw 19.2 Hot Red Peppers- dried 57.6 Pinto Beans- cooked9.4 Prunes- dried3.8 Tomatoes- raw1.4 Spinach- cooked7.0 Squash- cooked3.0

Screening 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 C Peproncinis- high at all locations, 557 ppm (green) to 2377 ppm (red) Pasilla, Anaheim, Marconi and Ancho also very high at red stage ppm TAM B36- Tropic Bell, highest at green stage: 600 ppm= 60 mg/100g

TAM Pasilla VR

Cultivar: B 36 (GR-RD) Vitamin C: ppm Flavonoid: 6-13 ppm

High β-carotene 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 127 Vitamin C: 1721 ppm Flavonoid: 45 ppm Beta-Carotene: 23.3 ppm

Habanero β-carotene TAM Mild- 760 µg/100gYucatan- 20 µg/100g

Vitamin C  -carotene Cultivar/line (mg·100g -1 ) x (µg·g -1 ) x Fruit type TAM Perlita a z 62.2 a z Western shipper- size 15 y TAM Uvalde15.2 b57.5 abWestern shipper- size 18 Explorer12.4 bc45.0 cdeWestern shipper- size 15 Cruiser12.1 bc36.3 eWestern shipper- size 12 Mission11.9 bc40.3 deWestern shipper- size 15 Green Ice11.8 bc4.70 fHoneydew- size 15 TAM Mayan11.2 bcd11.5 fCasaba- size 12 Gold Mark10.8 bcd41.4 cdeWestern shipper- size 12 TXC bcd49.8 bcWestern shipper- size 12 HMX cd46.0 cdWestern shipper- size 12 Valley Gold9.3 cd48.5 bcdWestern shipper- size 12 Mainpak9.2 cd43.5 cdeWestern shipper- size 12 Pronto8.0 cd43.0 cdeWestern shipper- size 12 TAM Dew Impr.7.2 cd4.70 fHoneydew- size 12 Primo7.0 cd56.7 abWestern shipper- size 12 z Mean separations by LSD, P ≤ Values followed by the same letter are not significantly different. y Sizes based on number of fruit which fit into a standard melon packing box. x Based on fresh weight. Fresh fruit vitamin C and beta-carotene contents of melons from Weslaco

Selection 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 Pollination

Developing 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’ Muskmelon Large, round fruit, Sz 9-12 High yield and resistant to PM High in beta-carotene Vitamin C, sugars

Genetic 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 Linkage RAPD marker OAC 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 OAC bp -600 bp

Figure 5. RAPD marker OAU expressing polymorphism between two DNA bulks from high and low ascorbic acid F 2 plants, and between ‘Dulce’ and TGR =’Dulce’, 2=TGR1551, 3=DNA bulk from high ascorbic acid F 2 plants, 4=DNA bulk from low ascorbic acid F 2 plants, and 5=molecular size marker bp -600bp -300bp OAU02.600

Molecular 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 Parents TAES B22CA 377 F1 Hybrid

-2072bp -600bp M -1500bp -300bp OL OL OL OL OL OL OL Fig. 1. Segregation of seven RAPD markers in an F2 population derived from the pepper cross of CA 377 x B to 20=F2 plants of the CA 377 x B 22 cross and M=a 100-bp DNA marker ladder.

Current Progress

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

Flavor Trumps Appearance

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