Breeding Vegetables for Optimum Levels of Phytochemicals

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

2. 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

3. Definitions • ANY HUMAN HANDLING OF PLANTS WHICH GENETICALLY ADAPTS THEM TO THE SERVICE OF MEN. • THE ART OF SELECTION BASED UPON THE SCIENCE OF • GENETICS. C. EVOLUTION DIRECTED BY THE WILL OF MAN. (Vavilov, 1935)

4. Wild Types vs. Improved

8. 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

9. 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

10. Dietary Fiber in ½ cup Serving

12. 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

13. 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- 1900-2280 ppm • TAM B36- Tropic Bell, highest at green stage: 600 ppm= 60 mg/100g

15. TAM Pasilla VR

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

17. 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)

18. Cultivar: C 127 Vitamin C: 1721 ppm Flavonoid: 45 ppm Beta-Carotene: 23.3 ppm

19. Habanero β-carotene TAM Mild- 760 µg/100g Yucatan- 20 µg/100g

20. Fresh fruit vitamin C and beta-carotene contents of melons from Weslaco Vitamin C -carotene Cultivar/line (mg·100g-1)x (µg·g-1)x Fruit type 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.

21. 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

22. Controlled Pollination

23. 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)

24. ‘Chujuc’ Muskmelon • Large, round fruit, Sz 9-12 • High yield and resistant to PM • High in beta-carotene Vitamin C, sugars

25. 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)

26. 1 2 3 4 5 -1500 bp OAC09.900 -600 bp DNA 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.

27. 1 2 3 4 5 -1500bp -600bp -300bp OAU02.600 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.

28. 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

29. High Antioxidant Parents TAES B22 CA 377 F1 Hybrid

30. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 M OL07.2050 -2072bp OL07.1700 OL07.1500 -1500bp OL07.1100 OL07.800 -600bp OL07.520 OL07.480 -300bp 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.

31. Current Progress

32. 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

33. 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

34. Improved Heirloom Types Introgressed virus, fusarium and heat resistance genes; developed more compact plants adapted to staked culture

35. Flavor Trumps Appearance

36. 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