Cloning and characterization of the nicotianamine synthase gene in Eruca vesicaria subsp sativa.

Nicotianamine (NA) is a ubiquitous metabolite in plants that bind heavy metals, is crucial for metal homeostasis, and is also an important metal chelator that facilitates long-distance metal transport and sequestration. NA synthesis is catalyzed by the enzyme nicotianamine synthase (NAS). Eruca vesicaria subsp sativa is highly tolerant to Ni, Pb, and Zn. In this study, a gene encoding EvNAS was cloned and characterized in E. vesicaria subsp sativa. The full-length EvNAS cDNA sequence contained a 111-bp 5'-untranslated region (UTR), a 155-bp 3'-UTR, and a 966-bp open reading frame encoding 322-amino acid residues. The EvNAS genomic sequence contained no introns, which is similar to previously reported NAS genes. The deduced translation of EvNAS contained a well-conserved NAS domain (1-279 amino acids) and an LIKI-CGEAEG box identical to some Brassica NAS and to the LIRL-box in most plant NAS, which is essential for DNA binding. Phylogenetic analysis indicated that EvNAS was most closely related to Brassica rapa NAS3 within the Cruciferae, followed by Thlaspi NAS1, Camelina NAS3, and Arabidopsis NAS3. A reverse transcription-polymerase chain reaction indicated that EvNAS expression was greatest in the leaves, followed by the flower buds and hypocotyls. EvNAS was moderately expressed in the roots.

The fate of tandemly duplicated genes assessed by the expression analysis of a group of Arabidopsis thaliana RING-H2 ubiquitin ligase genes of the ATL family.

Gene duplication events exert key functions on gene innovations during the evolution of the eukaryotic genomes. A large portion of the total gene content in plants arose from tandem duplications events, which often result in paralog genes with high sequence identity. Ubiquitin ligases or E3 enzymes are components of the ubiquitin proteasome system that function during the transfer of the ubiquitin molecule to the substrate. In plants, several E3s have expanded in their genomes as multigene families. To gain insight into the consequences of gene duplications on the expansion and diversification of E3s, we examined the evolutionary basis of a cluster of six genes, duplC-ATLs, which arose from segmental and tandem duplication events in Brassicaceae. The assessment of the expression suggested two patterns that are supported by lineage. While retention of expression domains was observed, an apparent absence or reduction of expression was also inferred. We found that two duplC-ATL genes underwent pseudogenization and that, in one case, gene expression is probably regained. Our findings provide insights into the evolution of gene families in plants, defining key events on the expansion of the Arabidopsis Tóxicos en Levadura family of E3 ligases.

Molecular cloning and functional characterization of a glutathione S-transferase involved in both anthocyanin and proanthocyanidin accumulation in Camelina sativa (Brassicaceae).

Recently, we found that the Arabidopsis TT19 protein, a glutathione S-transferase, has two functional domains that influence both anthocyanin and proanthocyanidin accumulation. To further understand the function of this protein in the other species, we cloned a cDNA encoding a glutathione S-transferase (namely CMGSTF12) from Camelina sativa, an oil crop that has received renewed interest due to its biofuel value and high omega-3 levels. Southern blot analysis demonstrated one copy of CMGSTF12 in C. sativa. Transformation of the Arabidopsis loss-of-function tt19-1 mutant with CMGSTF12 cDNA complemented accumulation of anthocyanin in vegetative tissues and resulted in the wild-type level of proanthocyanidin (both extractable and unextractable) in seeds. No obvious flavonoid accumulation changes were detected in the transgenic seeds, indicating that CMGSTF12 may only involve the lower flavonoid pathway, further proving that the TT19 protein controls accumulation of unextractable proanthocyanidin.

Evaluation of the impact of functional diversification on Poaceae, Brassicaceae, Fabaceae, and Pinaceae alcohol dehydrogenase enzymes.

The plant alcohol dehydrogenases (ADHs) have been intensively studied in the last years in terms of phylogeny and they have been widely used as a molecular marker. However, almost no information about their three-dimensional structure is available. Several studies point to functional diversification of the ADH, with evidence of its importance, in different organisms, in the ethanol, norepinephrine, dopamine, serotonin, and bile acid metabolism. Computational results demonstrated that in plants these enzymes are submitted to a functional diversification process, which is reinforced by experimental studies indicating distinct enzymatic functions as well as recruitment of specific genes in different tissues. The main objective of this article is to establish a correlation between the functional diversification occurring in the plant alcohol dehydrogenase family and the three-dimensional structures predicted for 17 ADH belonging to Poaceae, Brassicaceae, Fabaceae, and Pinaceae botanical families. Volume, molecular weight and surface areas are not markedly different among them. Important electrostatic and pI differences were observed with the residues responsible for some of them identified, corroborating the function diversification hypothesis. These data furnish important background information for future specific structure-function and evolutionary investigations.