T-DNA associated reciprocal translocation reveals differential survival of male and female gametes

In Arabidopsis thaliana, chromosomal rearrangements are commonly associated with compound T-DNA insertions due to endogenous double-stranded break and repair mechanisms. During the production of a double homozygous mutant for the CCCH zinc finger proteins, AtC3H6 and AtC3H68, we uncovered evidence for a reciprocal I-V chromosomal translocation in SALK_093620. Mapping the T-DNA borders in this insertion line confirmed an insertion site at the AtC3H6 locus on chromosome I and identified a second insertion in an intergenic region at the end of chromosome V. Our investigation of the progeny distribution and gamete transmission from reciprocal crosses indicated that male and female gametes are differentially affected by this predicted translocation. Male gametes with the haploid genotype AtC3H6(+);AtC3H68(+) had significantly higher transmission than female gametes with the same genotype. Our work highlights the importance of detailing T-DNA insertion events in transgenetic lines produced through Agrobacterium-mediated transformation, which can uncover novel chromosomal anomalies and imbalanced genome compositions.