Sucrose-responsive osmoregulation of plant cell size by a long non-coding RNA.

In plants, sugars are the key source of energy and metabolic building blocks. The systemic transport of sugars is essential for plant growth and morphogenesis. Plants evolved intricate molecular networks to effectively distribute sugars.

The brassinosteroid receptor gene safeguards cell-autonomous brassinosteroid signaling across tissues.

Brassinosteroid signaling is essential for plant growth as exemplified by the dwarf phenotype of loss-of-function mutants in (), a ubiquitously expressed Arabidopsis brassinosteroid receptor gene. Complementation of brassinosteroid-blind receptor mutants by expression with various tissue-specific promoters implied that local brassinosteroid signaling may instruct growth non-cell autonomously. Here, we performed such rescues with a panel of receptor variants and promoters, in combination with tissue-specific transgene knockouts.

An atlas of Brachypodium distachyon lateral root development.

The root system of plants is a vital part for successful development and adaptation to different soil types and environments. A major determinant of the shape of a plant root system is the formation of lateral roots, allowing for expansion of the root system. Arabidopsis thaliana, with its simple root anatomy, has been extensively studied to reveal the genetic program underlying root branching.

Ectopic assembly of an auxin efflux control machinery shifts developmental trajectories.

Polar auxin transport in the Arabidopsis (Arabidopsis thaliana) root tip maintains high auxin levels around the stem cell niche that gradually decrease in dividing cells but increase again once they transition toward differentiation. Protophloem differentiates earlier than other proximal tissues and employs a unique auxin "canalization" machinery that is thought to balance auxin efflux with retention. It consists of a proposed activator of PIN-FORMED (PIN) auxin efflux carriers, the cAMP-, cGMP- and Calcium-dependent (AGC) kinase PROTEIN KINASE ASSOCIATED WITH BRX (PAX); its inhibitor, BREVIS RADIX (BRX); and PHOSPHATIDYLINOSITOL-4-PHOSPHATE-5-KINASE (PIP5K) enzymes, which promote polar PAX and BRX localization.

Connecting emerging with existing vasculature above and below ground.

The vascular system was essential for plants to colonize land by facilitating the transport of water, nutrients, and minerals throughout the body. Our current knowledge on the molecular-genetic control of vascular tissue specification and differentiation is mostly based on studies in the Arabidopsis primary root. To what degree these regulatory mechanisms in the root meristem can be extrapolated to vascular tissue development in other organs is a question of great interest.

Single-gene resolution of diversity-driven overyielding in plant genotype mixtures.

In plant communities, diversity often increases productivity and functioning, but the specific underlying drivers are difficult to identify. Most ecological theories attribute positive diversity effects to complementary niches occupied by different species or genotypes. However, the specific nature of niche complementarity often remains unclear, including how it is expressed in terms of trait differences between plants.

Phloem development.

The evolution of the plant vascular system is a key process in Earth history because it enabled plants to conquer land and transform the terrestrial surface. Among the vascular tissues, the phloem is particularly intriguing because of its complex functionality. In angiosperms, its principal components are the sieve elements, which transport phloem sap, and their neighboring companion cells.

A phosphoinositide hub connects CLE peptide signaling and polar auxin efflux regulation.

Auxin efflux through plasma-membrane-integral PIN-FORMED (PIN) carriers is essential for plant tissue organization and tightly regulated. For instance, a molecular rheostat critically controls PIN-mediated auxin transport in developing protophloem sieve elements of Arabidopsis roots. Plasma-membrane-association of the rheostat proteins, BREVIS RADIX (BRX) and PROTEIN KINASE ASSOCIATED WITH BRX (PAX), is reinforced by interaction with PHOSPHATIDYLINOSITOL-4-PHOSPHATE-5-KINASE (PIP5K).

pH-dependent CLE peptide perception permits phloem differentiation in Arabidopsis roots.

The plant vasculature delivers phloem sap to the growth apices of sink organs, the meristems, via the interconnected sieve elements of the protophloem. In the A. thaliana root meristem, the stem cells form two files of protophloem sieve elements (PPSEs), whose timely differentiation requires a set of positive genetic regulators.

Heterologous expression of a lycophyte protein enhances angiosperm seedling vigor.

Seedling vigor is a key agronomic trait that determines juvenile plant performance. Angiosperm seeds develop inside fruits and are connected to the mother plant through vascular tissues. Their formation requires plant-specific genes, such as BREVIS RADIX (BRX) in Arabidopsis thaliana roots.

Auxin transport in developing protophloem: A case study in canalization.

Spatiotemporal cues orchestrate the development of organs and cellular differentiation in multicellular organisms. For instance, in the root apical meristem an auxin gradient patterns the transition from stem cell maintenance to transit amplification and eventual differentiation. Among the proximal tissues generated by this growth apex, the early, so-called protophloem, is the first tissue to differentiate.

A single-cell morpho-transcriptomic map of brassinosteroid action in the Arabidopsis root.

The effects of brassinosteroid signaling on shoot and root development have been characterized in great detail but a simple consistent positive or negative impact on a basic cellular parameter was not identified. In this study, we combined digital 3D single-cell shape analysis and single-cell mRNA sequencing to characterize root meristems and mature root segments of brassinosteroid-blind mutants and wild type. The resultant datasets demonstrate that brassinosteroid signaling affects neither cell volume nor cell proliferation capacity.

Metaphloem development in the Arabidopsis root tip.

The phloem transport network is a major evolutionary innovation that enabled plants to dominate terrestrial ecosystems. In the growth apices, the meristems, apical stem cells continuously produce early 'protophloem'. This is easily observed in Arabidopsis root meristems, in which the differentiation of individual protophloem sieve element precursors into interconnected conducting sieve tubes is laid out in a spatio-temporal gradient.

Mapping and engineering of auxin-induced plasma membrane dissociation in BRX family proteins.

Angiosperms have evolved the phloem for the long-distance transport of metabolites. The complex process of phloem development involves genes that only occur in vascular plant lineages. For example, in Arabidopsis thaliana, the BREVIS RADIX (BRX) gene is required for continuous root protophloem differentiation, together with PROTEIN KINASE ASSOCIATED WITH BRX (PAX).

BAM1/2 receptor kinase signaling drives CLE peptide-mediated formative cell divisions in roots.

Cell division is often regulated by extracellular signaling networks to ensure correct patterning during development. In , the SHORT-ROOT (SHR)/SCARECROW (SCR) transcription factor dimer activates ; () to drive formative divisions during root ground tissue development. Here, we show plasma-membrane-localized BARELY ANY MERISTEM1/2 (BAM1/2) family receptor kinases are required for -dependent formative divisions and expression, but not -dependent ground tissue specification.

Local auxin competition explains fragmented differentiation patterns.

Trajectories of cellular ontogeny are tightly controlled and often involve feedback-regulated molecular antagonism. For example, sieve element differentiation along developing protophloem cell files of Arabidopsis roots requires two antagonistic regulators of auxin efflux. Paradoxically, loss-of-function in either regulator triggers similar, seemingly stochastic differentiation failures of individual sieve element precursors.

Plant Biology: Brassinosteroids and the Intracellular Auxin Shuttle.

Throughout plant development, the phytohormones auxin and brassinosteroid regulate growth via their combinatorial input. A new study reveals a major impact of brassinosteroid signaling on intracellular auxin distribution and thereby nuclear auxin signaling, adding another layer of complexity to auxin-brassinosteroid crosstalk.

The transcription and export complex THO/TREX contributes to transcription termination in plants.

Transcription termination has important regulatory functions, impacting mRNA stability, localization and translation potential. Failure to appropriately terminate transcription can also lead to read-through transcription and the synthesis of antisense RNAs which can have profound impact on gene expression. The Transcription-Export (THO/TREX) protein complex plays an important role in coupling transcription with splicing and export of mRNA.

Local and Systemic Effects of Brassinosteroid Perception in Developing Phloem.

The plant vasculature is an essential adaptation to terrestrial growth. Its phloem component permits efficient transfer of photosynthates between source and sink organs but also transports signals that systemically coordinate physiology and development. Here, we provide evidence that developing phloem orchestrates cellular behavior of adjacent tissues in the growth apices of plants, the meristems.

Arabidopsis Flippases Cooperate with ARF GTPase Exchange Factors to Regulate the Trafficking and Polarity of PIN Auxin Transporters.

Cell polarity is a fundamental feature of all multicellular organisms. PIN auxin transporters are important cell polarity markers that play crucial roles in a plethora of developmental processes in plants. Here, to identify components involved in cell polarity establishment and maintenance in plants, we performed a forward genetic screening of :-; Arabidopsis () plants, which ectopically express predominantly basally localized PIN1 in root epidermal cells, leading to agravitropic root growth.

Plasma Membrane Domain Patterning and Self-Reinforcing Polarity in Arabidopsis.

Cell polarity is a key feature in the development of multicellular organisms. For instance, asymmetrically localized plasma-membrane-integral PIN-FORMED (PIN) proteins direct transcellular fluxes of the phytohormone auxin that govern plant development. Fine-tuned auxin flux is important for root protophloem sieve element differentiation and requires the interacting plasma-membrane-associated BREVIS RADIX (BRX) and PROTEIN KINASE ASSOCIATED WITH BRX (PAX) proteins.

Conditional effects of the epigenetic regulator JUMONJI 14 in root growth.

Methylation of lysine 4 in histone 3 (H3K4) is a post-translational modification that promotes gene expression. H3K4 methylation can be reversed by specific demethylases with an enzymatic Jumonji C domain. In , H3K4-specific JUMONJI (JMJ) proteins distinguish themselves by the association with an F/Y-rich (FYR) domain.

Peptide Signaling Pathways in Vascular Differentiation.

CLE peptide and related signaling pathways take up prominent roles in the development of both vascular tissues, xylem and phloem.