Genetically Controlled Seedcoat Color Variegation in TRITICUM AESTIVUM.

ARIEGATED seedcoat color was originally discovered in the variety Supreme (CI-8O26) which is reported to be a selection from Red Bobs (CI-6255) of hexaploid wheat, Triticum aestiuum L. The trait is characterized by a red and white variegated seedcoat and varying proportions of completely white-seeded tillers on plants with otherwise red o r variegated seeds, or red, white and variegated seeds at random or in sectors on individual spikes. Red, white and variegated seeds commonly produce plants that have all three types of seed. In previous studies of the variegation observed in Supreme, MYERS and POWERS (1938) found a high degree of meiotic instability (8.3% of the microspores contained micronuclei), a condition which they associated with seedcoat color variegation. However, both ELLIOTT and KONZAK (unpublished) observed that plants with variegated seeds appeared as segregates of crosses between Supreme or offspring from Supreme and many other varieties used in the wheat breeding program at Washington State University. Limited selection for red, white and variegated lines was practiced in Supreme, but was not very effective. One red seeded line bred true three generations, but with the limited number of lines from a small population of seeds tested, we cannot be certain of its origin. (The seeds tested were from the USDA World Collection, kindly sent to us by DR. J. C. CRADDOCK.) 'The present study was initiated in an attempt to identify the genetic nature and the causes of variegation and to determine the relationship of the phenomenon in Supreme to the action of known systems of genes. This paper reports some of the genetic and cytogenetic data gathered to date.