RESULTS
Pollen viability
As first noted by Burnham (1930), plants that are heterozygous for a reciprocal translocation
are predicted to create ca. 50% non-viable gametes. By contrast, plants that are homozygous
for a reciprocal translocation are genetically balanced and therefore are predicted to produce
gametes that are all viable. For a detailed discussion of the consequences of a reciprocal
translocation on gametogenesis see Curtis et al. (2009). As a first estimate of the frequency
with which translocations are present in T-DNA lines from the Salk collection (Alonso et
al., 2003), we examined the viability of pollen collected from plants that were heterozygous
for each of the T-DNA insertion alleles. Plants heterozygous for a translocation are expected
to produce 50% non-viable pollen. The 64 Salk T-DNA lines used for our study are listed in
Table 1. This collection of genes is composed mainly of protein kinase genes that our
laboratory is studying. Although this is not a random sample of Salk T-DNA lines, all of
these lines are viable when the T-DNA insertion is in the homozygous mutant state (data not
shown).