Plant Biology: New Insight into How Roots 'Mask Up'.

Extra- and trans-cellular barriers are essential for root function under even mild stress. New research shows that establishing both the lignin and suberin barriers in the Arabidopsis endodermis requires phenylpropanoid biosynthesis by endodermal cells themselves.

Polyamines and Legumes: Joint Stories of Stress, Nitrogen Fixation and Environment.

Polyamines (PAs) are natural aliphatic amines involved in many physiological processes in almost all living organisms, including responses to abiotic stresses and microbial interactions. On other hand, the family constitutes an economically and ecologically key botanical group for humans, being also regarded as the most important protein source for livestock. This review presents the profuse evidence that relates changes in PAs levels during responses to biotic and abiotic stresses in model and cultivable species within and examines the unreviewed information regarding their potential roles in the functioning of symbiotic interactions with nitrogen-fixing bacteria and arbuscular mycorrhizae in this family.

Metabolic responses to arbuscular mycorrhizal fungi are shifted in roots of contrasting soybean genotypes.

Modern breeding programs have reduced genetic variability and might have caused a reduction in plant colonization by arbuscular mycorrhizal fungi (AM). In our previous studies, mycorrhizal colonization was affected in improved soybean genotypes, mainly arbuscule formation. Despite substantial knowledge of the symbiosis-related changes of the transcriptome and proteome, only sparse clues regarding metabolite alterations are available.

P5CDH affects the pathways contributing to Pro synthesis after ProDH activation by biotic and abiotic stress conditions.

Plants facing adverse conditions usually alter proline (Pro) metabolism, generating changes that help restore the cellular homeostasis. These organisms synthesize Pro from glutamate (Glu) or ornithine (Orn) by two-step reactions that share Δ(1) pyrroline-5-carboxylate (P5C) as intermediate. In the catabolic process, Pro is converted back to Glu using a different pathway that involves Pro dehydrogenase (ProDH), P5C dehydrogenase (P5CDH), and P5C as intermediate.

Context of action of proline dehydrogenase (ProDH) in the Hypersensitive Response of Arabidopsis.

Background: Proline (Pro) dehydrogenase (ProDH) potentiates the oxidative burst and cell death of the plant Hypersensitive Response (HR) by mechanisms not yet elucidated. ProDH converts Pro into ∆1 pyrroline-5-carboxylate (P5C) and can act together with P5C dehydrogenase (P5CDH) to produce Glu, or with P5C reductase (P5CR) to regenerate Pro and thus stimulate the Pro/P5C cycle. To better understand the effects of ProDH in HR, we studied the enzyme at three stages of the defense response differing in their ROS and cell death levels.

A salicylic acid-induced lectin-like protein plays a positive role in the effector-triggered immunity response of Arabidopsis thaliana to Pseudomonas syringae Avr-Rpm1.

Salicylic acid (SA) is one of the key hormones that orchestrate the pathogen-induced immune response in plants. This response is often characterized by the activation of a local hypersensitive reaction involving programmed cell death, which constrains proliferation of biotrophic pathogens. Here, we report the identification and functional characterization of an SA-induced legume lectin-like protein 1 (SAI-LLP1), which is coded by a gene that belongs to the group of early SA-activated Arabidopsis genes.

Proline dehydrogenase is a positive regulator of cell death in different kingdoms.

Proline dehydrogenase (ProDH) catalyzes the flavin-dependent oxidation of Pro into Δ1-pyrroline-5-carboxylate (P5C). This is the first of the two enzymatic reactions that convert proline (Pro) into glutamic acid (Glu). The P5C thus produced is non-enzymatically transformed into glutamate semialdehyde (GSA), which acts as a substrate of P5C dehydrogenase (P5CDH) to generate Glu.

Proline dehydrogenase contributes to pathogen defense in Arabidopsis.

L-proline (Pro) catabolism is activated in plants recovering from abiotic stresses associated with water deprivation. In this catabolic pathway, Pro is converted to glutamate by two reactions catalyzed by proline dehydrogenase (ProDH) and Δ(1)-pyrroline-5-carboxylate dehydrogenase (P5CDH), with Δ(1)-pyrroline-5-carboxylate (P5C) as the intermediate. Alternatively, under certain conditions, the P5C derived from Pro is converted back to Pro by P5C reductase, thus stimulating the Pro-P5C cycle, which may generate reactive oxygen species (ROS) as a consequence of the ProDH activity.

Features of basal and race-specific defences in photosynthetic Arabidopsis thaliana suspension cultured cells.

Plant suspension cell cultures display many features of the innate immune responses observed in planta and have been extensively applied to the study of basal and race-specific defences. However, no single model including photosynthetic cultured cells has been used for the exhaustive characterization of both basal and race-specific defences to date. In this article, we report the activation of basal and race-specific defences in green cultured cells from Arabidopsis thaliana.