INHERITANCE OF VARIEGATION IN BARLEY

Abstract

A strain of variegated barley that originated in a Saskatchewan field produces, on selfing, progeny of which approximately 90% are albino, the remainder striped or variegated with rare full green exceptions. In crosses, variegated ♂ × green ♀ produced 7 albino, 4 striped, and 11 green F₁ plants. The reciprocal cross yielded 1 striped and 41 green F₁ plants. F₂ segregation approximated three green to one of all others (albino and variegated). From some F₂ and F₃ progenies it was inferred that two genetic factor pairs might be segregating. On that hypothesis the dominant hypostatic factor for variegation must be very unstable, mutating at a high rate to white. The peculiarities of inheritance may be explained also, however, on the basis of a combination of gene and (maternal) plastid inheritance. On this interpretation the plastids present in the egg affect the colour of the seedling that develops from it. When green plastids or proplastids are present in the egg, many of them, but not necessarily all, are induced to mutate if the white w gene is homozygous, but fewer if the w gene is heterozygous. If white plastids only are present in the egg it is probable that the seedling will be an albino regardless of gene content.