Genetic factors determining plasticity in flax genotrophs

Abstract

Changes in the amount of nuclear DNA can be induced in 'Stormont Cirrus', a plastic variety (PL) of flax, by different environments, but not in the linseed variety 'Royal' (R) which is not plastic. PL is thought to contain nuclear and cytoplasmic factors, not possessed by R, which are necessary for the plastic characters to appear. Further crosses have shown that the PL nuclear factor plays a direct part in the determination of plasticity and that the cytoplasmic factor is maintained in the presence of both PL and R nuclei. Insofar as the genetic analysis has been taken, the distribution of genetic factors determining plasticity (+) or nonplasticity (−) in PL and R are as follows: nuclear factor (PL, +; R, −); cytoplasmic factor (PL, +; R, −); nuclear factor for synthesizing de nouveau cytoplasmic factor (PL, −; R, −); nuclear factor for maintaining the cytoplasmic factor (PL, +; R, +); site at which DNA changes occur (PL, +; R, +). It is suggested that the nuclear factor is activated by the cytoplasmic factor, and must come directly from a cytoplasm containing the cytoplasmic factor to be operative.Key words: flax, genotype plasticity, plasticity, genotrophs.