Uncoupling FRUITFULL's functions through modification of a protein motif identified by co-ortholog analysis.

Many plant transcription factors (TFs) are multifunctional and regulate growth and development in more than one tissue. These TFs can generally associate with different protein partners depending on the tissue type, thereby regulating tissue-specific target gene sets. However, how interaction specificity is ensured is still largely unclear.

ABA signalling promotes cell totipotency in the shoot apex of germinating embryos.

Somatic embryogenesis (SE) is a type of induced cell totipotency where embryos develop from vegetative tissues of the plant instead of from gamete fusion after fertilization. SE can be induced in vitro by exposing explants to growth regulators, such as the auxinic herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The plant hormone abscisic acid (ABA) has been proposed to be a downstream signalling component at the intersection between 2,4-D- and stress-induced SE, but it is not known how these pathways interact to induce cell totipotency.

The chemical compound 'Heatin' stimulates hypocotyl elongation and interferes with the Arabidopsis NIT1-subfamily of nitrilases.

Temperature passively affects biological processes involved in plant growth. Therefore, it is challenging to study the dedicated temperature signalling pathways that orchestrate thermomorphogenesis, a suite of elongation growth-based adaptations that enhance leaf-cooling capacity. We screened a chemical library for compounds that restored hypocotyl elongation in the pif4-2-deficient mutant background at warm temperature conditions in Arabidopsis thaliana to identify modulators of thermomorphogenesis.

A plant-based chemical genomics screen for the identification of flowering inducers.

Background: Floral timing is a carefully regulated process, in which the plant determines the optimal moment to switch from the vegetative to reproductive phase. While there are numerous genes known that control flowering time, little information is available on chemical compounds that are able to influence this process. We aimed to discover novel compounds that are able to induce flowering in the model plant Arabidopsis.

Cross-Talk Between Sporophyte and Gametophyte Generations Is Promoted by CHD3 Chromatin Remodelers in Arabidopsis thaliana.

Angiosperm reproduction requires the integrated development of multiple tissues with different genotypes. To achieve successful fertilization, the haploid female gametophytes and diploid ovary must coordinate their development, after which the male gametes must navigate through the maternal sporophytic tissues to reach the female gametes. After fertilization, seed development requires coordinated development of the maternal diploid integuments, the triploid endosperm, and the diploid zygote.

Sequence motifs in MADS transcription factors responsible for specificity and diversification of protein-protein interaction.

Protein sequences encompass tertiary structures and contain information about specific molecular interactions, which in turn determine biological functions of proteins. Knowledge about how protein sequences define interaction specificity is largely missing, in particular for paralogous protein families with high sequence similarity, such as the plant MADS domain transcription factor family. In comparison to the situation in mammalian species, this important family of transcription regulators has expanded enormously in plant species and contains over 100 members in the model plant species Arabidopsis thaliana.

New aspects of CLAVATA2, a versatile gene in the regulation of Arabidopsis development.

In order to unravel the functions of receptor-like proteins in Arabidopsis (AtRLPs), including the CLAVATA2 (CLV2) receptor, we employed a reverse genetics approach. In previous studies, we assembled a genome-wide collection of AtRLP gene T-DNA insertion mutants and reported on the biological roles of a few AtRLPs closely related to CLV2. In this study, we showed that over-expression of CLV2 in wild-type plants unexpectedly resulted in a multi-carpel phenotype, mimicking the clv2 mutant, which suggests a co-suppression effect on the endogenous CLV2.

Receptor-like proteins: searching for functions.

Receptor-like proteins (RLPs) are cell surface receptors, which are composed of several distinct domains including a signal peptide, an extracellular leucine-rich repeat (LRR) region, a transmembrane domain and a short cytoplasmic tail. RLPs are implicated in plant growth and development as well as in disease resistance. Our previous genome-wide functional analysis of 57 Arabidopsis RLP genes (AtRLPs) revealed that mutant phenotypes were only observed for a few genes including the two reported genes CLAVATA2 (CLV2) and TOO MANY MOUTHS, despite the wide range of growth and developmental stages and treatments that were tested.

CLE peptide signaling during plant development.

Peptide signaling in plants is a rapid developing area of research which focuses on so called peptide hormones. These signaling molecules are utilized for inter-cellular communication in different developmental processes, beside the usage of the more well-known phytohormones. Probably the best studied peptide ligands in plants are the CLAVATA3 (CLV3)/ENDOSPERM SURROUNDING REGION (ESR)-related (CLE) proteins.

Functional analyses of the CLAVATA2-like proteins and their domains that contribute to CLAVATA2 specificity.

The Arabidopsis (Arabidopsis thaliana) CLAVATA2 (CLV2) gene encodes a leucine-rich repeat receptor-like protein (RLP) that is involved in controlling the stem cell population size in the shoot apical meristem. Our previous genome-wide functional analysis of 57 AtRLP genes revealed only a few phenotypes for mutant alleles, despite screening a wide range of growth and developmental stages and assaying sensitivity to various stress responses, including susceptibility toward pathogens. To gain further insight into the biological role of AtRLPs, in particular CLV2-related AtRLP genes, we tested their ability to complement the clv2 mutant phenotype.

Combination of reversible male sterility and doubled haploid production by targeted inactivation of cytoplasmic glutamine synthetase in developing anthers and pollen.

Reversible male sterility and doubled haploid plant production are two valuable technologies in F(1)-hybrid breeding. F(1)-hybrids combine uniformity with high yield and improved agronomic traits, and provide self-acting intellectual property protection. We have developed an F(1)-hybrid seed technology based on the metabolic engineering of glutamine in developing tobacco anthers and pollen.

CLE peptide ligands and their roles in establishing meristems.

Research in the past decade revealed that peptide ligands, also called peptide hormones, play a crucial role in intercellular communication and defense response in plants. Recent studies demonstrated that a family of plant-specific genes, CLAVATA3 (CLV3)/ENDOSPERM SURROUNDING REGION (ESR) (CLE), which has at least 31 members in Arabidopsis genome, are able to generate extracellular peptides to regulate cell division and differentiation. A hydroxyl 12-amino acid peptide derived from the conserved CLE motif of CLV3 promotes cell differentiation, whereas another CLE-derived peptide suppresses the differentiation.

The CLAVATA3/ESR motif of CLAVATA3 is functionally independent from the nonconserved flanking sequences.

It is believed that CLAVATA3 (CLV3) encodes a peptide ligand that interacts with the CLV1/CLV2 receptor complex to limit the number of stem cells in the shoot apical meristem of Arabidopsis thaliana; however, the exact composition of the functional CLV3 product remains a mystery. A recent study on CLV3 shows that the CLV3/ESR (CLE) motif, together with the adjacent C-terminal sequence, is sufficient to execute CLV3 function when fused behind an N-terminal sequence of ERECTA. Here we show that most of the sequences flanking the CLE motif of CLV3 can be deleted without affecting CLV3 function.

The 14-amino acid CLV3, CLE19, and CLE40 peptides trigger consumption of the root meristem in Arabidopsis through a CLAVATA2-dependent pathway.

CLAVATA3 (CLV3), CLV3/ESR19 (CLE19), and CLE40 belong to a family of 26 genes in Arabidopsis thaliana that encode putative peptide ligands with unknown identity. It has been shown previously that ectopic expression of any of these three genes leads to a consumption of the root meristem. Here, we show that in vitro application of synthetic 14-amino acid peptides, CLV3p, CLE19p, and CLE40p, corresponding to the conserved CLE motif, mimics the overexpression phenotype.

Mis-expression of the CLV3/ESR-like gene CLE19 in Arabidopsis leads to a consumption of root meristem.

Mild heat shock treatment (32 degrees C) of isolated Brassica napus microspores triggers a developmental switch from pollen maturation to embryo formation. This in vitro system was used to identify genes expressed in globular to heart-shape transition embryos. One of the genes isolated encodes a putative extra-cellular protein that exhibits high sequence similarity with the in silico identified CLV3/ESR-related 19 polypeptide from Arabidopsis (AtCLE19) and was therefore named BnCLE19.