Radiation-induced polygenic mutation in Arabidopsis thaliana II. Analysis of lines selected for flowering time

Radiation-induced polygenic mutation in Arabidopsis thaliana

“…Similarly, flowering time mutations can be either dominant or recessive, dominance is generally incomplete, and there is no evidence for non-allelic interaction (Lawrence, 1968b).…”

“…The flowering time data, details concerning experimental design and derivation of the parental lines have already been published (Lawrence, 1968b). …”

“…PREVIOUS papers in this series have examined the selection (Lawrence,1 968a) and analysis (Lawrence, 1968b(Lawrence, , 1975a of radiation-induced quantitative variation in flowering time, and the selection (Lawrence, 1975b) of variation in the number of seeds per pod in the crucifer Arabidopsis thaliana (Heyn. ).…”

“…No evidence was found for mutations increasing the number of seeds per pod. In this respect, the induced mutations affecting the number of seeds per pod contrast with those influencing flowering time, since, with these, approximately equal numbers act in the early and late directions (Lawrence, 1968a).Similarly, flowering time mutations can be either dominant or recessive, dominance is generally incomplete, and there is no evidence for non-allelic interaction (Lawrence, 1968b).Two out of six low selection lines included in the 13 x 13 diallel, and one high line, appeared to be homozygous for interchanges or similar chromosome aberrations and these may be responsible for the marked lack of linearity in the relation between selection response and dose. Correlated changes in the unselected character flowering time were negligible in lines selected for number of seeds per pod and vice versa, though one extremely late and infertile line was obtained.…”

The assessment of induced continuous variation in pure-breeding lines following selfing

“…This information is far from ideal for model fitting and it is particularly unsatisfactory for detecting and estimating non-additive sources ofvariation. Where, therefore, a primary objective is an understanding of the nature of the induced variation and its genetical architecture one of the many mating systems specially designed for this purpose, such as test crosses (Kearsey andJinks, 1968 andVirk andJinks, 1977) or diallel sets of crosses (see Mather andJinks, 1971, andDickinson andJinks, 1956) should be used either on early generation material such as the M2 or on inbreds derived from it (Lawrence, 1968).…”