The role of AtMUS81 in interference-insensitive crossovers in A. thaliana.

MUS81 is conserved among plants, animals, and fungi and is known to be involved in mitotic DNA damage repair and meiotic recombination. Here we present a functional characterization of the Arabidopsis thaliana homolog AtMUS81, which has a role in both mitotic and meiotic cells. The AtMUS81 transcript is produced in all tissues, but is elevated greater than 9-fold in the anthers and its levels are increased in response to gamma radiation and methyl methanesulfonate treatment.

Pollen tetrad-based visual assay for meiotic recombination in Arabidopsis.

Recombination, in the form of cross-overs (COs) and gene conversion (GC), is a highly conserved feature of meiosis from fungi to mammals. Recombination helps ensure chromosome segregation and promotes allelic diversity. Lesions in the recombination machinery are often catastrophic for meiosis, resulting in sterility.

Separation of Arabidopsis pollen tetrads is regulated by QUARTET1, a pectin methylesterase gene.

Arabidopsis (Arabidopsis thaliana) QUARTET (QRT) genes are required for pollen separation during normal floral development. In qrt mutants, the four products of microsporogenesis remain fused and pollen grains are released as tetrads. In Arabidopsis, tetrad analysis in qrt mutants has been used to map all five centromeres, easily distinguish sporophytic from gametophytic mutations, and accurately assess crossover interference.

Identification of Arabidopsis thaliana transformants without selection reveals a high occurrence of silenced T-DNA integrations.

Several recent investigations of T-DNA integration sites in Arabidopsis thaliana have reported 'cold spots' of integration, especially near centromeric regions. These observations have contributed to the ongoing debate over whether T-DNA integration is random or occurs preferentially in transcriptionally active regions. When transgenic plants are identified by selecting or screening for transgenic activity, transformants with integrations into genomic regions that suppress transcription, such as heterochromatin, may not be identified.