Law and order in plants - the origin and functional relevance of phyllotaxis.

The regular arrangement of organs (phyllotaxis) in vegetative shoots and flowers is one of the most stunning features of plants. Spiral patterns characterized by Fibonacci numbers have attracted the particular interest of natural scientists and mathematicians. Numerous reviews have dealt with the molecular genetic mechanisms underlying phyllotaxis, and modeling studies have sought to recreate phyllotaxis according to mathematical, biochemical, or physical laws.

Fusarium oxysporum infection activates the plastidial branch of the terpenoid biosynthesis pathway in flax, leading to increased ABA synthesis.

Upregulation of the terpenoid pathway and increased ABA content in flax upon Fusarium infection leads to activation of the early plant's response (PR genes, cell wall remodeling, and redox status). Plants have developed a number of defense strategies against the adverse effects of fungi such as Fusarium oxysporum. One such defense is the production of antioxidant secondary metabolites, which fall into two main groups: the phenylpropanoids and the terpenoids.

Meristem development and activity in gametophytes of the model fern, Ceratopteris richardii.

Ceratopteris richardii is a model fern species widely used to analyze various developmental processes and their regulation in gametophytes. The form of mature C. richardii gametophytes depends on the activity of the marginal meristem, but knowledge on meristem formation and structure is limited.

Impairment of Meristem Proliferation in Plants Lacking the Mitochondrial Protease AtFTSH4.

Shoot and root apical meristems (SAM and RAM, respectively) are crucial to provide cells for growth and organogenesis and therefore need to be maintained throughout the life of a plant. However, plants lacking the mitochondrial protease AtFTSH4 exhibit an intriguing phenotype of precocious cessation of growth at both the shoot and root apices when grown at elevated temperatures. This is due to the accumulation of internal oxidative stress and progressive mitochondria dysfunction.

Leaf arrangements are invalid in the taxonomy of orchid species.

The selection and validation of proper distinguishing characters are of crucial importance in taxonomic revisions. The modern classifications of orchids utilize the molecular tools, but still the selection and identification of the material used in these studies is for the most part related to general species morphology. One of the vegetative characters quoted in orchid manuals is leaf arrangement.

The mitochondrial protease AtFTSH4 safeguards Arabidopsis shoot apical meristem function.

The shoot apical meristem (SAM) ensures continuous plant growth and organogenesis. In LD 30 °C, plants lacking AtFTSH4, an ATP-dependent mitochondrial protease that counteracts accumulation of internal oxidative stress, exhibit a puzzling phenotype of premature SAM termination. We aimed to elucidate the underlying cellular and molecular processes that link AtFTSH4 with SAM arrest.

Dichotomous branching: the plant form and integrity upon the apical meristem bifurcation.

The division of the apical meristem into two independently functioning axes is defined as dichotomous branching. This type of branching typically occurs in non-vascular and non-seed vascular plants, whereas in seed plants it presents a primary growth form only in several taxa. Dichotomy is a complex process, which requires a re-organization of the meristem structure and causes changes in the apex geometry and activity.

Changes in accumulation of heteroplasmic mitochondrial DNA and frequency of recombination via short repeats during plant lifetime in Phaseolus vulgaris.

Recombination via short repeats in plant mitochondrial genomes results in sublimons--DNA molecules with a copy number much lower compared to the main mitochondrial genome. Coexistence of stoichiometrically different mitotypes, called heteroplasmy, plays an important evolutionary role, since sublimons occasionally replace the main genome resulting in a new plant phenotype. It is not clear, how frequency of recombination and sublimon production is regulated and how it is related to changes in the quantity of the main genome and sublimons.

Mitochondrial protease AtFtsH4 protects ageing Arabidopsis rosettes against oxidative damage under short-day photoperiod.

Mitochondrial atftsh4 protease, whose catalytic site is exposed to the intermembrane space, is one of four inner membrane-bound ftsh proteases in arabidopsis. we found that the loss of atftsh4 altered arabidopsis leaf morphology at the late stage of rosette growth under short-day photoperiod, while such changes were not observed in mutants grown under long days. these morphological changes were correlated with elevated levels of both reactive oxygen species (ros) and carbonylated proteins, which strongly suggested that ageing plants experienced oxidative stress.

The lack of mitochondrial AtFtsH4 protease alters Arabidopsis leaf morphology at the late stage of rosette development under short-day photoperiod.

AtFtsH4 is one of four inner membrane-bound mitochondrial ATP-dependent metalloproteases in Arabidopsis thaliana, called AAA proteases, whose catalytic site is exposed to the intermembrane space. In the present study, we used a reverse-genetic approach to investigate the physiological role of the AtFtsH4 protease. We found that loss of AtFtsH4 did not significantly affect Arabidopsis growth under optimal conditions (long days); however, severe morphological and developmental abnormalities in late rosette development occurred under short-day conditions.

Vascular architecture in shoots of early divergent vascular plants, Lycopodium clavatum and Lycopodium annotinum.

Lycopodium represents a phylogenetically distinct clade of basal vascular plants with anatomical characters that have no parallel in other lineages. Thus, knowledge of lycopod structure and development may reveal important information about the common ancestors of all vascular plants. Here we report the unique architecture of the conducting system in Lycopodium annotinum and Lycopodium clavatum.