ARS | Publication request: ENZYMATIC DARKENING OF TUBER FLESH IN SOLANUM HJERTINGII AND SELECTED CULTIVATED POTATOES

Submitted to: Potato Association of America Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 1996
Publication Date: N/A

Technical Abstract: Solanum hjertingii, an allotetraploid wild species native to Mexico, has been previously reported as having little or no enzymatic darkening of the tuber flesh. We report here studies of tuber flesh darkening with and without addition of tyrosine and of polyphenol oxidase (PPO) activity of S. hjertingii compared to selected cultivated diploid and tetraploid potatoes. .Four seedlings each of five plant introduction accessions (PI) were studie to allow for an analysis of within and between accession variability. Solanum hjertingii displayed much less tuber darkening than cultivated potato. The measurement of flesh darkening of the lightest S. hjertingii seedling was one-fifth of the lightest cultivated potato. Within S. hjertingii the reading of the lightest clone was one fourth the darkest. The variance component within PI's was significant, accounting for 26 percent of the total variance for tuber darkening. The mean PPO activity of S. hjertingii was approximately one third of the cultivated potato mean while the lowest value for S. hjertingii was three percent of the lowest value in cultivated potato. PPO activity was most closely correlated with tuber flesh darkening when tryosine was added. Lack of, or reduced, PPO activity is an essential feature of, though not the only explanation of the reduced darkening trait. The between PI variance component for PPO was significant, accounting for half the total variance. Solanum hjertingii is a potentially valuable germplasm source for reduced tuber flesh darkening.