5 Arabidopsis Genetics

Abstract

Arabidopsis thaliana (L.) Heynh. is a true diploid plant and does not differ in its basic genetics from other diploid plants. Specific features of its reproductive biology, however, such as its being a self-fertilizing species with bisexual flowers, indicate that certain types of genetic analysis should be performed differently than with, e.g., maize. Genetic analysis requires genetic variation for specific traits. This variation can be induced by various types of mutagenic treatment or can be found as “natural” variation within and between wild populations.

The analysis of genetic variation should answer the following questions:

How many genes control the observed variation?

What are the dominance relations between the various alleles?

Are the genes allelic to previously described genes?

What are the epistatic relations with other genes?

Does the respective gene act in a cell-autonomous fashion or in a non-cell-autonomous way?

Where is the gene located on the linkage map?

The main features of Arabidopsis that enable an efficient (classical) genetic analysis are its short generation time and its small size, which provides a limited space requirement. Arabidopsis is almost 100% self-pollinating in greenhouse and climate chamber conditions. In natural populations, outcrossing is a rare phenomenon, although heterozygote individuals are sometimes found (Abbott and Gomes 1989). Studies with artificial populations constructed from mutant lines led to estimates of 1–2% outcrossing. However, under conditions of high pollinator activity and in genotypes with a certain degree of male sterility, higher outcrossing rates have been reported (Abbott...