Hormone signalling and root development: an update on the latest Arabidopsis thaliana research

2007 ◽  
Vol 34 (3) ◽  
pp. 163 ◽  
Author(s):  
Jose Manuel Perez-Perez

Plants are sessile organisms whose developmental programs depend mainly on environmental cues that are sensed and interpreted through hormonal signalling pathways. Roots are specialised plant organs that are instrumental during water and nutrient uptake, biotic interactions, stress responses and for mechanical support. Our knowledge about the basic molecular events shaping root patterning and growth has advanced significantly in the past few years thanks to the use of Arabidopsis thaliana (L.) Heynh. as a model system. In this review, I will discuss recent findings that indicate crosstalk between growth regulators and hormone signalling pathways during primary root development. Further comparative research using non-model species will shed light on the conserved developmental modules among distant lineages involved in root architecture.

Cells ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2576
Author(s):  
Brenda Anabel López-Ruiz ◽  
Estephania Zluhan-Martínez ◽  
María de la Paz Sánchez ◽  
Elena R. Álvarez-Buylla ◽  
Adriana Garay-Arroyo

As sessile organisms, plants must adjust their growth to withstand several environmental conditions. The root is a crucial organ for plant survival as it is responsible for water and nutrient acquisition from the soil and has high phenotypic plasticity in response to a lack or excess of them. How plants sense and transduce their external conditions to achieve development, is still a matter of investigation and hormones play fundamental roles. Hormones are small molecules essential for plant growth and their function is modulated in response to stress environmental conditions and internal cues to adjust plant development. This review was motivated by the need to explore how Arabidopsis thaliana primary root differentially sense and transduce external conditions to modify its development and how hormone-mediated pathways contribute to achieve it. To accomplish this, we discuss available data of primary root growth phenotype under several hormone loss or gain of function mutants or exogenous application of compounds that affect hormone concentration in several abiotic stress conditions. This review shows how different hormones could promote or inhibit primary root development in A. thaliana depending on their growth in several environmental conditions. Interestingly, the only hormone that always acts as a promoter of primary root development is gibberellins.


Author(s):  
Mercedes Schroeder ◽  
Melissa Y. Gomez ◽  
Nathan K. McLain ◽  
Emma Gachomo

Beneficial rhizobacteria can stimulate changes in plant root development. While root system growth is mediated by multiple factors, the regulated distribution of the phytohormone auxin within root tissues plays a principal role. Auxin transport facilitators help to generate the auxin gradients and maxima that determine root structure. Here, we show that the plant growth-promoting rhizobacterial strain Bradyrhizobium japonicum IRAT FA3 influences specific auxin efflux transporters to alter Arabidopsis thaliana root morphology. Gene expression profiling of host transcripts in control and B. japonicum-inoculated roots of the wild type A. thaliana accession Col-0 confirmed upregulation of PIN2, PIN3, PIN7 and ABCB19 with B. japonicum and identified genes potentially contributing to a diverse array of auxin-related responses. Co-cultivation of the bacterium with loss-of-function auxin efflux transport mutants revealed that B. japonicum requires PIN3, PIN7 and ABCB19 to increase lateral root development and utilizes PIN2 to reduce primary root length. Accelerated lateral root primordia production due to B. japonicum was not observed in single pin3, pin7 or abcb19 mutants, suggesting independent roles for PIN3, PIN7 and ABCB19 during the plant-microbe interaction. Our work demonstrates B. japonicum’s influence over host transcriptional reprogramming during plant interaction with this beneficial microbe and the subsequent alterations to root system architecture.


2020 ◽  
Author(s):  
Hardik P. Gala ◽  
Amy Lanctot ◽  
Ken Jean-Baptiste ◽  
Sarah Guiziou ◽  
Jonah C. Chu ◽  
...  

AbstractRoot architecture is a major determinant of fitness, and is under constant modification in response to favorable and unfavorable environmental stimuli. Beyond impacts on the primary root, the environment can alter the position, spacing, density and length of secondary or lateral roots. Lateral root development is among the best-studied examples of plant organogenesis, yet there are still many unanswered questions about its earliest steps. Among the challenges faced in capturing these first molecular events is the fact that this process occurs in a small number of cells with unpredictable timing. Single-cell sequencing methods afford the opportunity to isolate the specific transcriptional changes occurring in cells undergoing this fate transition. Using this approach, we successfully captured the transcriptomes of initiating lateral root primordia, and discovered many previously unreported upregulated genes associated with this process. We developed a method to selectively repress target gene transcription in the xylem pole pericycle cells where lateral roots originate, and demonstrated that expression of several of these targets was required for normal root development. We also discovered novel subpopulations of cells in the pericycle and endodermal cell files that respond to lateral root initiation, highlighting the coordination across cell files required for this fate transition.One sentence summarySingle cell RNA sequencing reveals new molecular details about lateral root initiation, including the transcriptional impacts of the primordia on bordering cells.


Genes ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 633 ◽  
Author(s):  
Muhammad Asim ◽  
Zia Ullah ◽  
Fangzheng Xu ◽  
Lulu An ◽  
Oluwaseun Olayemi Aluko ◽  
...  

Root system architecture (RSA) is required for the acquisition of water and mineral nutrients from the soil. One of the essential nutrients, nitrate (NO3−), is sensed and transported by nitrate transporters NRT1.1 and NRT2.1 in the plants. Nitrate transporter 1.1 (NRT1.1) is a dual-affinity nitrate transporter phosphorylated at the T101 residue by calcineurin B-like interacting protein kinase (CIPKs); it also regulates the expression of other key nitrate assimilatory genes. The differential phosphorylation (phosphorylation and dephosphorylation) strategies and underlying Ca2+ signaling mechanism of NRT1.1 stimulate lateral root growth by activating the auxin transport activity and Ca2+-ANR1 signaling at the plasma membrane and the endosomes, respectively. NO3− additionally functions as a signal molecule that forms a signaling system, which consists of a vast array of transcription factors that control root system architecture that either stimulate or inhibit lateral and primary root development in response to localized and high nitrate (NO3−), respectively. This review elucidates the so-far identified nitrate transporters, nitrate sensing, signal transduction, and the key roles of nitrate transporters and its downstream transcriptional regulatory network in the primary and lateral root development in Arabidopsis thaliana under stress conditions.


2021 ◽  
Vol 134 (19) ◽  
Author(s):  
Sophie Dittmer ◽  
Tatjana Kleine ◽  
Serena Schwenkert

ABSTRACT Molecular chaperones play an important role during the response to different stresses. Since plants are sessile organisms, they need to be able to adapt quickly to different conditions. To do so, plants possess a complex chaperone machinery, composed of HSP70, HSP90, J proteins and other factors. In this study we characterized DJC31 (also known as TPR16) and DJC62 (also known as TPR15) of Arabidopsis thaliana, two J proteins that additionally carry clamp-type tetratricopeptide repeat domains. Using cell fractionation and split GFP, we could show that both proteins are attached to the cytosolic side of the endoplasmic reticulum membrane. Moreover, an interaction with cytosolic HSP70.1 and HSP90.2 could be shown using bimolecular fluorescence complementation. Knockout of both DJC31 and DJC62 caused severe defects in growth and development, which affected almost all organs. Furthermore, it could be shown that the double mutant is more sensitive to osmotic stress and treatment with abscisic acid, but surprisingly exhibited enhanced tolerance to drought. Taken together, these findings indicate that DJC31 and DJC62 might act as important regulators of chaperone-dependent signaling pathways involved in plant development and stress responses.


2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Guiomar Martín ◽  
Yamile Márquez ◽  
Federica Mantica ◽  
Paula Duque ◽  
Manuel Irimia

Abstract Background Alternative splicing (AS) is a widespread regulatory mechanism in multicellular organisms. Numerous transcriptomic and single-gene studies in plants have investigated AS in response to specific conditions, especially environmental stress, unveiling substantial amounts of intron retention that modulate gene expression. However, a comprehensive study contrasting stress-response and tissue-specific AS patterns and directly comparing them with those of animal models is still missing. Results We generate a massive resource for Arabidopsis thaliana, PastDB, comprising AS and gene expression quantifications across tissues, development and environmental conditions, including abiotic and biotic stresses. Harmonized analysis of these datasets reveals that A. thaliana shows high levels of AS, similar to fruitflies, and that, compared to animals, disproportionately uses AS for stress responses. We identify core sets of genes regulated specifically by either AS or transcription upon stresses or among tissues, a regulatory specialization that is tightly mirrored by the genomic features of these genes. Unexpectedly, non-intron retention events, including exon skipping, are overrepresented across regulated AS sets in A. thaliana, being also largely involved in modulating gene expression through NMD and uORF inclusion. Conclusions Non-intron retention events have likely been functionally underrated in plants. AS constitutes a distinct regulatory layer controlling gene expression upon internal and external stimuli whose target genes and master regulators are hardwired at the genomic level to specifically undergo post-transcriptional regulation. Given the higher relevance of AS in the response to different stresses when compared to animals, this molecular hardwiring is likely required for a proper environmental response in A. thaliana.


Genes ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 249
Author(s):  
Weimiao Liu ◽  
Liai Xu ◽  
Hui Lin ◽  
Jiashu Cao

The growth of plant cells is inseparable from relaxation and expansion of cell walls. Expansins are a class of cell wall binding proteins, which play important roles in the relaxation of cell walls. Although there are many members in expansin gene family, the functions of most expansin genes in plant growth and development are still poorly understood. In this study, the functions of two expansin genes, AtEXPA4 and AtEXPB5 were characterized in Arabidopsis thaliana. AtEXPA4 and AtEXPB5 displayed consistent expression patterns in mature pollen grains and pollen tubes, but AtEXPA4 also showed a high expression level in primary roots. Two single mutants, atexpa4 and atexpb5, showed normal reproductive development, whereas atexpa4atexpb5 double mutant was defective in pollen tube growth. Moreover, AtEXPA4 overexpression enhanced primary root elongation, on the contrary, knocking out AtEXPA4 made the growth of primary root slower. Our results indicated that AtEXPA4 and AtEXPB5 were redundantly involved in pollen tube growth and AtEXPA4 was required for primary root elongation.


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