The function of AIP6 during seedling establishment in Arabidopsis.

Living organisms increase their chances of surviving adverse environmental conditions either by relocating to more favorable environments or by transitioning into a stress resistant state of arrested development. Plants use the latter strategy to cope with abiotic and biotic stresses. Arabidopsis thaliana, as all other seed bearing plants, arrests its development at two pre-programmed checkpoints during embryogenesis. A third checkpoint may be engaged after germination if the seedling encounters the stress of premature desiccation, or if it is exposed to the stress hormone abscisic acid (ABA), high salt or sugars. It involves ABA response factors ABI3 and ABI5. The ability to arrest development only lasts for 2 to 3 days after germination, indicating that the response is intended to protect the seedlings before they become established as self-sustaining plants.

Previously in our laboratory, yeast two-hybrid screening was used to identify ABI3 interacting protein 6 (AIP6), which contains a distinctive RING finger domain, found on a large number of eukaryotic E3 ubiquitin ligases that target proteins for degradation via the 26S proteasome. The hypothesis that AIP6 may be linked to ABI3 function will be examined using genetic and molecular approaches. AIP6 mRNA and protein levels will be analyzed during embryogenesis and seedling establishment in wild type and aip6 mutant plants, and compared to the expression of ABI3 in order to examine the role of AIP6 in relation to the stability of ABI3.