Strigo-D2-a bio-sensor for monitoring spatio-temporal strigolactone signaling patterns in intact plants.

Strigolactones (SLs) are a class of plant hormones that mediate biotic interactions and modulate developmental programs in response to endogenous and exogenous stimuli. However, a comprehensive view on the spatio-temporal pattern of SL signaling has not been established, and tools for a systematic in planta analysis do not exist. Here, we present Strigo-D2, a genetically encoded ratiometric SL signaling sensor that enables the examination of SL signaling distribution at cellular resolution and is capable of rapid response to altered SL levels in intact Arabidopsis (Arabidopsis thaliana) plants.

Tissue-specific transcriptome profiling of the Arabidopsis inflorescence stem reveals local cellular signatures.

Genome-wide gene expression maps with a high spatial resolution have substantially accelerated plant molecular science. However, the number of characterized tissues and growth stages is still small due to the limited accessibility of most tissues for protoplast isolation. Here, we provide gene expression profiles of the mature inflorescence stem of Arabidopsis thaliana covering a comprehensive set of distinct tissues.

SUPPRESSOR OF MAX2 1-LIKE 5 promotes secondary phloem formation during radial stem growth.

As a pre-requisite for constant growth, plants produce vascular tissues at different sites within their post-embryonic body. Interestingly, the formation of vascular tissues during longitudinal and radial expansion of shoot and root axes differs fundamentally with respect to its anatomical configuration. This raises the question to which level regulatory mechanisms of vascular tissue formation are shared throughout plant development.

ARF5/MONOPTEROS directly regulates miR390 expression in the primary root meristem.

The root meristem is organized around a quiescent center (QC) surrounded by stem cells that generate all cell types of the root. In the transit-amplifying compartment, progeny of stem cells further divides prior to differentiation. Auxin controls the size of this transit-amplifying compartment via auxin response factors (ARFs) that interact with auxin response elements (AuxREs) in the promoter of their targets.

Spatial specificity of auxin responses coordinates wood formation.

Spatial organization of signalling events of the phytohormone auxin is fundamental for maintaining a dynamic transition from plant stem cells to differentiated descendants. The cambium, the stem cell niche mediating wood formation, fundamentally depends on auxin signalling but its exact role and spatial organization is obscure. Here we show that, while auxin signalling levels increase in differentiating cambium descendants, a moderate level of signalling in cambial stem cells is essential for cambium activity.

MOL1 is required for cambium homeostasis in Arabidopsis.

Plants maintain pools of pluripotent stem cells which allow them to constantly produce new tissues and organs. Stem cell homeostasis in shoot and root tips depends on negative regulation by ligand-receptor pairs of the CLE peptide and leucine-rich repeat receptor-like kinase (LRR-RLK) families. However, regulation of the cambium, the stem cell niche required for lateral growth of shoots and roots, is poorly characterized.

(Pro)cambium formation and proliferation: two sides of the same coin?

The body of higher plants is usually pervaded by the (pro)cambium, a reticulate system of meristematic cells harboring the potential for producing vascular tissues at critical times and places. The (pro)cambium thereby provides the basis for the differential modulation of long-distance transport capacities and plant body stability. Distinct regulatory networks responsible for the initiation and proliferation of (pro)cambium cells have been identified.

Root branching: mechanisms, robustness, and plasticity.

Plants are sessile organisms that must efficiently exploit their habitat for water and nutrients. The degree of root branching impacts the efficiency of water uptake, acquisition of nutrients, and anchorage. The root system of plants is a dynamic structure whose architecture is determined by modulation of primary root growth and root branching.

Cytoplasmic Arabidopsis AGO7 accumulates in membrane-associated siRNA bodies and is required for ta-siRNA biogenesis.

Formation of trans-acting small interfering RNAs (ta-siRNAs) from the TAS3 precursor is triggered by the AGO7/miR390 complex, which primes TAS3 for conversion into double-stranded RNA by the RNA-dependent RNA polymerase RDR6 and SGS3. These ta-siRNAs control several aspects of plant development. The mechanism routing AGO7-cleaved TAS3 precursor to RDR6/SGS3 and its subcellular organization are unknown.

Long Nonprotein-Coding RNAs in Plants.

In recent years, nonprotein-coding RNAs (or npcRNAs) have emerged as a major part of the eukaryotic transcriptome. Many new regulatory npcRNAs or riboregulators riboregulators have been discovered and characterized due to the advent of new genomic approaches. This growing number suggests that npcRNAs could play a more important role than previously believed and significantly contribute to the generation of evolutionary complexity in multicellular organisms.

miR390, Arabidopsis TAS3 tasiRNAs, and their AUXIN RESPONSE FACTOR targets define an autoregulatory network quantitatively regulating lateral root growth.

Plants adapt to different environmental conditions by constantly forming new organs in response to morphogenetic signals. Lateral roots branch from the main root in response to local auxin maxima. How a local auxin maximum translates into a robust pattern of gene activation ensuring the proper growth of the newly formed lateral root is largely unknown.