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Title: Effects of Verticillium dahliae infection on stem-end chip defect development in potatoes (Solanum tuberosum L.)

Author
item WANG, YI - University Of Wisconsin
item Bethke, Paul

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2012
Publication Date: 1/9/2013
Citation: Wang, Y., Bethke, P.C. 2013. Effects of Verticillium dahliae infection on stem-end chip defect development in potatoes (Solanum tuberosum L.). Crop Science. 53(2):595-601.

Interpretive Summary: High quality potato products cannot be made from tubers with defects. One important defect of potatoes used to make potato chips is stem-end chip defect. Tubers with this defect produce chips that have unsightly, dark-colored spots at one end of the chip. Shipments of tubers that contain a high percentage of defect tubers may be rejected at chip processing plants. This increases the financial risk faced by growers and introduces uncertainty about supply available to processors. Field research in which potato plants were grown in locations with high and low fungal disease pressure was conducted to assess the potential involvement of Verticillium, a soil borne fungal pathogen, on the development of stem-end chip defect. Potato plants that were more severely infected with the pathogen also had more severe defects in tubers. These data suggest that selection of varieties resistant to Verticillium or field management to minimize Verticillium infection can reduce the incidence of stem-end chip defects.

Technical Abstract: Potato chips are America's favorite snack food with annual retail sales of over $6 billion. Stem-end chip defect, which is characterized by discoloration of the vasculature and surrounding tissues at the tuber stem end portion of chips, is an important tuber quality concern for US chip production. The cause of stem-end chip defect is not known. Verticillium wilt, caused by a vascular fungal pathogen Verticillium dahliae, is a persistent potato disease that causes early plant senescence and yield reductions. A two-year field trial was conducted to investigate the effects of V. dahliae on stem-end chip defect development and the activity of acid invertase at the apical (bud) and basal (stem) ends of the tuber. Our results show that potato plants that were more infected with V. dahliae had a higher incidence of severe stem-end chip defects than plants with less V. dahliae infection. V. dahliae infection is correlated with an the up-regulation of acid invertase activity in tubers resulting in accumulation of reducing sugars, which are the direct cause of dark color on chips due to Maillard reaction.