A mutation in the essential and widely conserved DAMAGED DNA BINDING1-Cullin4 ASSOCIATED FACTOR gene OZS3 causes hypersensitivity to zinc excess, cold and UV stress in Arabidopsis thaliana.

The overly zinc sensitive Arabidopsis thaliana mutant ozs3 shows reduced growth of the primary root, which is exacerbated by an excess specifically of Zn ions. In addition, ozs3 plants display various subtle developmental phenotypes, such as longer petioles and early flowering. Also, ozs3 seedlings are completely but reversibly growth-arrested when shifted to 4°C. The causal mutation was mapped to a gene encoding a putative substrate-recognition receptor of cullin4 E3 ligases. OZS3 orthologous genes can be found in almost all eukaryotic genomes. Most species from Schizosaccharomyces pombe to Homo sapiens, and including A. thaliana, possess one ortholog. No functional data are available for these genes in any of the multicellular model systems. CRISPR-Cas9-mediated knockout demonstrated that a complete loss of OZS3 function is embryo-lethal, indicating essentiality of OZS3 and its orthologs. The OZS3 protein interacts with the adaptor protein DAMAGED DNA BINDING1 (DDB1) in the nucleus. Thus, it is indeed a member of the large yet poorly characterized family of DDB1-cullin4 associated factors in plants. Mutant phenotypes of ozs3 plants are apparently caused by the weakened DDB1-OZS3 interaction as a result of the exchange of a conserved amino acid near the conserved WDxR motif.

Ontogenetic changes of 2-propenyl and 3-indolylmethyl glucosinolates in Brassica carinata leaves as affected by water supply.

Concentrations of 2-propenyl and 3-indolylmethyl glucosinolates in two lines of Brassica carinata (Holeta-1 and 37-A) were assessed during the vegetative life cycle under optimal or drought-inducing water supply conditions. In the well-watered treatment, 2-propenyl and 3-indolylmethyl glucosinolate concentrations remained almost constant from the 6-8 to the 15-16 leaf stage, whereas a drought-induced water supply led to a distinct increase of these glucosinolates. Generally, the 2-propenyl concentration was higher in Holeta-1 at each leaf stage under drought stress as compared with 37-A, indicating a B. carinata line-specific drought response. The drought-induced glucosinolate accumulation seems to be integrated in the plant's process of osmotic adjustment. It seems that under drought, there is a shift from primary to secondary metabolism, thereby promoting glucosinolate synthesis. Thus, by keeping the relative soil-water content below 80%, glucosinolate concentrations could be increased up to the 15-16 leaf stage, resulting in better plant nutritional quality of B. carinata.