Plants Gain Improved Salt-Stress Tolerance and Increased Storage Oil Biosynthesis by Interfering with CRL3 Activities.

Generating new strategies to improve plant performance and yield in crop plants becomes increasingly relevant with ongoing and predicted global climate changes. E3 ligases that function as key regulators within the ubiquitin proteasome pathway often are involved in abiotic stress responses, development, and metabolism in plants. The aim of this research was to transiently downregulate an E3 ligase that uses BTB/POZ-MATH proteins as substrate adaptors in a tissue-specific manner.

Using CRL3 E3 ligase substrate recognition sites as tools to impact plant development and stress tolerance in .

Cullin-based RING E3 ligases that use BTB/POZ-MATH (BPM) proteins as substrate receptors have been established over the last decade as critical regulators in plant development and abiotic stress tolerance. As such they affect general aspects of shoot and root development, flowering time, embryo development, and different abiotic stress responses, such as heat, drought and salt stress. To generate tools that can help to understand the role of CRL3 E3 ligases in plants, we developed a novel system using two conserved protein-binding motifs from BPM substrates to transiently block CRL3 activity.

Plant E3 Ligases and Their Role in Abiotic Stress Response.

Plants, as sessile organisms, have limited means to cope with environmental changes. Consequently, they have developed complex regulatory systems to ameliorate abiotic stresses im-posed by environmental changes. One such system is the ubiquitin proteasome pathway, which utilizes E3 ligases to target proteins for proteolytic degradation via the 26S proteasome.

Characterization of R2R3 S23 MYB Transcription Factors as Novel Targets of the Ubiquitin Proteasome-Pathway and Regulators of Salt Stress and Abscisic Acid Response.

Rapid response to environmental changes and abiotic stress to coordinate developmental programs is critical for plants. To accomplish this, plants use the ubiquitin proteasome pathway as a flexible and efficient mechanism to control protein stability and to direct cellular reactions. Here, we show that all three members of the R2R3 S23 MYB transcription factor subfamily, MYB1, MYB25, and MYB109, are degraded by the 26S proteasome, likely facilitated by a CUL3-based E3 ligase that uses MATH-BTB/POZ proteins as substrate adaptors.

Aspartate Residues in a Forisome-Forming SEO Protein Are Critical for Protein Body Assembly and Ca2+ Responsiveness.

Forisomes are protein bodies known exclusively from sieve elements of legumes. Forisomes contribute to the regulation of phloem transport due to their unique Ca2+-controlled, reversible swelling. The assembly of forisomes from sieve element occlusion (SEO) protein monomers in developing sieve elements and the mechanism(s) of Ca2+-dependent forisome contractility are poorly understood because the amino acid sequences of SEO proteins lack conventional protein-protein interaction and Ca2+-binding motifs.

Effect of low-temperature storage on the content of folate, vitamin B , ascorbic acid, chlorogenic acid, tyrosine, and phenylalanine in potatoes.

Background: Changes in the metabolite composition of potato tubers during low-temperature storage can affect their nutritional value, susceptibility to bruising, and processing qualities. Here, we measured changes in the amounts of folate, vitamin B , and vitamin C, and the blackspot pigment precursors chlorogenic acid and tyrosine, as well as phenylalanine, in five potato varieties stored at 7.8 °C for 8 months in 2015 and 2016.

Characterization of RAP2.4-Related Proteins in Stress Response and as CUL3-Dependent E3 Ligase Substrates.

The turnip has important economic value and represents a good model system to study gene function in crop plants. ERF/AP2 transcription factors are a major group of proteins that are often involved in regulating stress-responses and developmental programs. Some ERF/AP2 proteins are targets of CULLIN3-based E3 ligases that use BTB/POZ-MATH proteins as substrate receptors.

Composition, roles, and regulation of cullin-based ubiquitin e3 ligases.

Due to their sessile nature, plants depend on flexible regulatory systems that allow them to adequately regulate developmental and physiological processes in context with environmental cues. The ubiquitin proteasome pathway, which targets a great number of proteins for degradation, is cellular tool that provides the necessary flexibility to accomplish this task. Ubiquitin E3 ligases provide the needed specificity to the pathway by selectively binding to particular substrates and facilitating their ubiquitylation.

Arabidopsis thaliana PDX1.2 is critical for embryo development and heat shock tolerance.

PDX1.2 is expressed in the basal part of the globular-stage embryo, and plays critical roles in development, hypocotyl elongation, and stress response. The Arabidopsis thaliana PDX1.

Genotype-specific changes in vitamin B6 content and the PDX family in potato.

Vitamin B6 is one of the most versatile cofactors in plants and an essential phytonutrient in the human diet that benefits a variety of human health aspects. Although biosynthesis of the vitamin has been well resolved in recent years, the main research is currently based on Arabidopsis thaliana with very little work done on major crop plants. Here we provide the first report on interactions and expression profiles of PDX genes for vitamin B6 biosynthesis in potato and how vitamin B6 content varies in tubers of different genotypes.

The AFB4 auxin receptor is a negative regulator of auxin signaling in seedlings.

The plant hormone auxin is perceived by a family of F box proteins called the TIR1/auxin-signaling F box proteins (AFBs). Phylogenetic studies reveal that these proteins fall into four clades in flowering plants called TIR1, AFB2, AFB4, and AFB6. Genetic studies indicate that members of the TIR1 and AFB2 groups act as positive regulators of auxin signaling.

Arabidopsis DDB1a and DDB1b are critical for embryo development.

DNA Damaged binding protein 1 (DDB1) is a highly conserved protein of around 125 kDa. It serves as a substrate adaptor subunit to a CUL4-based E3 ubiquitin ligase within the ubiquitin proteasome pathway. However, based on a set of three beta-propellers, the protein is able to mediate various protein-protein interactions, suggesting that it participates in many developmental and physiological processes in the plant.

Vitamin B6: a molecule for human health?

Vitamin B6 is an intriguing molecule that is involved in a wide range of metabolic, physiological and developmental processes. Based on its water solubility and high reactivity when phosphorylated, it is a suitable co-factor for many biochemical processes. Furthermore the vitamin is a potent antioxidant, rivaling carotenoids or tocopherols in its ability to quench reactive oxygen species.

Vitamin B6: Killing two birds with one stone?

Vitamin B6 comprises a group of compounds that are involved in a surprisingly high diversity of biochemical reactions. Actually, most of these reactions are co-catalyzed by a single B6 vitamer, pyridoxal 5'-phosphate, making it a crucial and versatile co-factor in many metabolic processes in the cell. In addition, it has been demonstrated in recent years that vitamin B6 has a second important function by being an effective antioxidant.

Vitamin B6: a long known compound of surprising complexity.

In recent years vitamin B6 has become a focus of research describing the compound's critical function in cellular metabolism and stress response. For many years the sole function of vitamin B6 was considered to be that of an enzymatic cofactor. However, recently it became clear that it is also a potent antioxidant that effectively quenches reactive oxygen species and is thus of high importance for cellular well-being.

The Pdx1 family is structurally and functionally conserved between Arabidopsis thaliana and Ginkgo biloba.

Vitamin B6 is one of the most important compounds in living organisms, and its biosynthesis has only recently been understood. Because it is required for more than 100 biochemical reactions, lack of the vitamin is fatal. This is of special importance to mammals and humans, which cannot biosynthesize the vitamin and thus depend on its external uptake.