A biotech approach to tackle the acrylamide problem of potato. Jiming Jiang University of Wisconsin-Madison

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1 A biotech approach to tackle the acrylamide problem of potato Jiming Jiang University of Wisconsin-Madison

2 The Potato Value in the U.S. 1. #3 food crop, ~125 pounds per capita consumption in the U.S. since 1990s 2. $3.45 billions in farm value (2010), >$10 billion processing industry 3. Exports: seed potato, starch, chips, French fry ($1.5 billions in 2011)

3 How long can you leave your potatoes from grocery store in your kitchen? The shelf life of packaged potato chips?

4 This is why potato cannot be stored under room temperature!

5 Ok! We all know the problems, but we can store the potatoes under cold temperature to avoid these problems, right? Room temperature stored (22 C) for 30 days Cold stored (4 C) for 30 days

6 The Acrylamide Problem Amino acids + Sugars Frying Maillard reaction Acrylamide What is acrylamide? Acrylamide is a chemical used primarily as a building block in making polyacrylamide and acrylamide copolymers, which are widely used used in many industrial processes, such as the production of paper, dyes, and plastics.. Acrylamide in food. Researchers have found acrylamide in certain foods that were heated to a temperature above 120C degrees, but not in foods prepared below this temperature. Potato chips and French fries were found to contain higher levels of acrylamide compared with other food.. Does acrylamide increase the risk of cancer? Studies in rodent models have found that acrylamide exposure poses a risk for several types of cancer. However, the evidence from human studies is still incomplete. The National Toxicology Program and the International Agency for Research on Cancer consider acrylamide to be a probable human carcinogen, based on studies in laboratory animals given acrylamide in drinking water. However, toxicology studies have shown differences in acrylamide absorption rates between humans and rodents..

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8 Food with the highest amounts of acrylamide (Survey by FDA) Kettle Gourmet Potato Chips 1265 Route 11 Sweet Potato Chips 2726 Roxx French Fries 1250 Blue Mesa Grill Sweet Potato Chips 4080 Opeyes french fries 1030 Postum Caffeine Free Hot Beverage 5399 Lamb Weston Inland Valley Fajita Fries 1325 Snyder's of Hanover Veggie Crisps 1340 Lay's Nat. Baked Potato Crisps 1096 Hershey's Cocoa 909 Pringles BBQ Potato Crisps 2510 Wheatena Toasted Wheat Cereal 1184 Trader Joe's Veggie Chips Potato Snacks 1970 Nabisco Grahams 944 Richfood Shoestring Potatoes 1243 Super G Chopped Ripe Olives 1925 Good Health Natural Foods Potato Stix 1168 Lipton Onion Soup & Dip Mix 1184

9 The crazy carbohydrate pathways in tubers J. R. Sowokinos, 2001, Am. J. Potato Res. Vacuolar Invertase Gene Sucrose 4 (Vacuole) Glucose + Fructose

10 Silencing the Vinv gene by RNAi interference Control 15 different silencing lines

11 Silencing the Vinv gene by RNA interference #7 #6 # # #3 #1 #2 Katahdin control 30% silencing 50% silencing 80% silencing 90% silencing 99.5% silencing 99% silencing 99% silencing

12 Katahdin 20 C, 60 days Katahdin 4 C, 14 days Katahdin 4 C, 60 days Katahdin 4 C, 90 days Katahdin 4 C, 180 days Line #1 20 C, 60 days Line #1 4 C, 14 days Line #1 4 C, 60 days Line #1 4 C, 90 days Line #1 4 C, 180 days

13 Potato chips from Hancock-grown potatoes Katahdin, 20 C/14d Line #3, 20 C/14d Line #2, 20 C/14d Line #1, 20 C/14d Katahdin, 4 C/14d Line #3, 4 C/14d Line #2, 4 C/14d Line #1, 4 C/14d Katahdin, 4 C/60d Line #3, 4 C/60d Line #2, 4 C/60d Line #1, 4 C/60d

14 Potato chip color from different RNAi lines after 30 days at 4 C storage

15 Parts Per Billion Acrylamide in chips from field-grown potatoes

16 Sucrose 4 Glucose + Fructose

17 Glucose profiles of Katahdin and RNAi lines Katahdin RNAi #10 (Not Silenced) RNAi #7 (50% silenced) RNAi #5 (80% silenced) RNAi #1 (99% silenced)

18 Acid invertase (nmol glu min -1 mg -1 P) Acid invertase activity in potato tubers stored for 14 days at 4 C (39 F) Line#1 Line#2 Line#3 Line#4 Katahdin

19 Yield (Kg) Yield (g) Yield of Vinv silencing lines? Hancock, 2009 Hancock, 2010

20 What do we exactly introduce into potato during gene silencing? Vinv gene ( ~2.4 kb) RCR amplification Vinv gene fragment ( ~0.5 kb) Introduce into the phellsgate silencing vector Introduce into potato plants Small RNA derived from the ~0.5 kb Vinv gene fragment will cause silencing of the normal Vinv gene

21 Why I am optimistic? 1. We will be able to convert any current potato variety into a coldinduced sweetening resistant cultivar! 2. Vinv gene silencing is probably the effective/economical approach to control acrylamide in potato. 3. We are not introducing an alien gene into potato, but a DNA fragment from a gene that is native to potato.

22 一箭双雕 Two birds, One stone

23 Acknowledgements: Bala Pudota Lei Wu Xiaobiao Zhu Jim Busse Andy Hamernik Shelley Jansky Alvin Bussan Ruofang Zhang Paul Bethke