Plant hormones (Literature sources on phytohormones and plant signalling)

Authors: Yalin Li, Xinyu Yang, Xuewen Li, Chuang Wang, Guangda Ding, Fangsen Xu, Sheliang Wang, Hongmei Cai, John P. Hammond, Sergey Shabala, Min Yu and Lei Shi.

Plant and Soil (2023)

Abstract: "Aims - The aims of this work were to investigate phosphate starvation responses of Brassica napus (B. napus) under heterogeneous phosphate (Pi) supply and the regulatory role of jasmonic acid (JA) in the systemic response to Pi starvation. Methods - A split-root system with two separated compartments was employed to mimic heterogeneous Pi distribution in the soil and to examine the effect of heterogeneous Pi supply, and JA or DIECA (JA biosynthesis inhibitor) on growth, root morphology, Pi concentration, Acid phosphatase (APase) activity, nutrition uptake, JA concentration and expression of Pi starvation systemically-induced (PSSI) genes of B. napus. Results - Heterogeneous Pi supply systemically modified root morphology that increased the total root surface area (TRSA), total root volume (TRV), total root length (TRL) and total lateral root number (TLRN) of root with local Pi supply (R +) and decreased them of root with local no Pi supply (R-) when compared to root with homogeneous Pi supply (R + +) and root devoid of Pi (R–), respectively. Anthocyanin, APase activity and JA concentration in shoot and root of B. napus were systemically regulated by heterogeneous Pi supply. In addition, heterogeneous Pi supply significantly promoted nutrient uptake when compared with homogeneous no Pi supply. Root morphology of B. napus was significantly changed by exogenous addition of JA or DIECA in a split-root system. JA enhanced Pi starvation response by inducing expression of PSSI genes in shoots and roots. Conclusions - Our results suggest that JA enhances systemic Pi starvation response of B. napus by regulating root morphology, Pi homeostasis and inducing expression of PSSI genes under heterogeneous Pi supply."

Authors: Hieu Trang Nguyen, Mohamad Cheaib, Marie Fournel, Maelle Rios, Pascal Gantet, Laurent Laplaze, Soazig Guyomarc’h, Michael Riemann,Thierry Heitz, Anne-Sophie Petitot and Antony Champion.

PLoS ONE (2023)

Abstract: "COI1-mediated perception of jasmonate is critical for plant development and responses to environmental stresses. Monocots such as rice have two groups of COI genes due to gene duplication: OsCOI1a and OsCOI1b that are functionally equivalent to the dicotyledons COI1 and OsCOI2 whose function remains unclear. In order to assess the function of OsCOI2 and its functional redundancy with COI1 genes, we developed a series of rice mutants in the 3 genes OsCOI1a, OsCOI1b and OsCOI2 by CRISPR Cas9-mediated editing and characterized their phenotype and responses to jasmonate. Characterization of OsCOI2 uncovered its important roles in root, leaf and flower development. In particular, we show that crown root growth inhibition by jasmonate relies on OsCOI2 and not on OsCOI1a nor on OsCOI1b, revealing a major function for the non-canonical OsCOI2 in jasmonate-dependent control of rice root growth. Collectively, these results point to a specialized function of OsCOI2 in the regulation of plant development in rice and indicate that sub-functionalisation of jasmonate receptors has occurred in the monocot phylum."

Authors: Naga Jyothi Pullagurla, Supritam Shome, Ranjana Yadav and Debabrata Laha.

bioRxiv (2023)

Abstract: "Jasmonic acid (JA) is a plant hormone that regulates a plethora of physiological processes including immunity and development and is perceived by the F-Box protein, Coronatine-insensitive protein 1(COI1). The discovery of inositol phosphates (InsPs) in the COI1 receptor complex highlights their role in JA perception. InsPs are phosphate-rich signaling molecules that control many aspects of plant physiology. Inositol pyrophosphates (PP-InsPs) are diphosphate containing InsP species of which InsP7 and InsP8 are the best characterized ones. Different InsP and PP-InsP species are linked with JA-related plant immunity. However, role of PP-InsP species in regulating JA-dependent developmental processes are poorly understood. Recent identification of ITPK1 kinase responsible for the production of 5-InsP7 from InsP6 in planta provides a platform to interrogate possible involvement of ITPK-derived InsP species in JA-related plant development. Herein this study, we report that ITPK1-defective plants exhibit increased root growth inhibition to bioactive JA treatment. The itpk1 plants also show increased lateral root density when treated with JA. Notably, JA treatment does not induce ITPK1 protein level. Gene expression analyses revealed that JA-biosynthetic genes are not differentially expressed in the ITPK1-deficient plants. We further demonstrate that genes encoding different JAZ repressor proteins are severely downregulated in the ITPK1-defective plants. Taken together, our study highlights the role of ITPK1 in regulating JA-dependent root architecture development through controlling expression of different JAZ repressor proteins."

Authors: Gilad Gabay, Hanchao Wang, Junli Zhang, Jorge Moriconi, German F. Burguener, Tyson R Howell, Adam Lukaszewski, Brian Staskawicz, Myeong-Je Cho, Jaclyn Tanaka, Tzion Fahima, Haiyan Ke, Katayoon Dehesh, Guo-Liang Zhang, Jin-Ying Gou, Mats Hamberg, Guillermo Santa Maria and Jorge Dubcovsky.

bioRxiv (2022)

Abstract: "Wheat is an essential crop for global food security and is well adapted to a wide variety of soils. However, the gene networks regulating different root architectures remain poorly understood. We report here the identification of a cluster of a monocot-specific 12-OXOPHYTODIENOATE REDUCTASE genes from subfamily III (OPRIII) that modulate key differences in wheat root architecture associated with grain yield under water-limited conditions. Wheat plants with a loss-of-function mutation in OPRIII showed longer seminal roots, whereas plants with increased OPRIII dosage or transgenic over-expression showed reduced seminal root growth, precocious development of lateral roots and increased jasmonic acid (JA). A JA-biosynthesis inhibitor eliminated the root differences, confirming a JA-mediated mechanism. Multiple transcriptome analysis of transgenic and wild-type lines revealed significant enriched JA-biosynthetic and reactive oxygen species (ROS) pathways that paralleled changes in ROS distribution. The OPRIII genes provide a useful entry point to engineer root architecture in wheat and other cereals."

Authors: Logan DeMott, Paula R. Oblessuc, Alice Pierce, Joseph Student and Maeli Melotto.

The Plant Journal (2021)

Abstract: "Jasmonic acid (JA) signaling controls several processes related to plant growth, development, and defense, which are modulated by the transcription regulator and receptor JASMONATE-ZIM DOMAIN (JAZ) proteins. We recently discovered that a member of the JAZ family, JAZ4 has a prominent function in canonical JA signaling as well as other mechanisms. Here, we discovered the existence of two naturally occurring splice variants (SVs) of JAZ4 in planta, JAZ4.1 and JAZ4.2, and employed biochemical and pharmacological approaches to determine protein stability and repression capability of these SVs within JA signaling. We then utilized quantitative and qualitative transcriptional studies to determine spatiotemporal expression and splicing patterns in vivo, which revealed developmental-, tissue-, and organ-specific regulation. Detailed phenotypic and expression analyses suggest a role of JAZ4 in ethylene (ET) and auxin signaling pathways differentially within the zones of root development in seedlings. These results support a model in which JAZ4 functions as a negative regulator of ET signaling and auxin signaling in root tissues above the apex. However, in the root apex JAZ4 functions as a positive regulator of auxin signaling possibly independently of ET. Collectively, our data provides insight into the complexity of spatiotemporal regulation of JAZ4 and how this impacts hormone signaling specificity and diversity in Arabidopsis roots."

Authors: Camilla Betti, Federica Della Rovere, Diego Piacentini, Laura Fattorini, Giuseppina Falasca and Maria Maddalena Altamura.

Biomolecules (2021)

Abstract: "Developmental and environmental signaling networks often converge during plant growth in response to changing conditions. Stress-induced hormones, such as jasmonates (JAs), can influence growth by crosstalk with other signals like brassinosteroids (BRs) and ethylene (ET). Nevertheless, it is unclear how avoidance of an abiotic stress triggers local changes in development as a response. It is known that stress hormones like JAs/ET and BRs can regulate the division rate of cells from the first asymmetric cell divisions (ACDs) in meristems, suggesting that stem cell activation may take part in developmental changes as a stress-avoidance-induced response. The root system is a prime responder to stress conditions in soil. Together with the primary root and lateral roots (LRs), adventitious roots (ARs) are necessary for survival in numerous plant species. AR and LR formation is affected by soil pollution, causing substantial root architecture changes by either depressing or enhancing rooting as a stress avoidance/survival response. Here, a detailed overview of the crosstalk between JAs, ET, BRs, and the stress mediator nitric oxide (NO) in auxin-induced AR and LR formation, with/without cadmium and arsenic, is presented. Interactions essential in achieving a balance between growth and adaptation to Cd and As soil pollution to ensure survival are reviewed here in the model species Arabidopsis and rice."

Authors: Javier Raya-González, Jesús Salvador López-Bucio and José López-Bucio.

Journal of Plant Growth Regulation (2023)

Abstract: "The MEDIATOR complex is a large multiprotein assembly ubiquitous to eukaryotic organisms that acts as a transcriptional coactivator. Although its identification in plants is relatively recent, accumulating information points to critical functions played by each of its subunits to orchestrate growth, development, and stress adaptation. Here, we review recent advances in understanding the functions of MEDIATOR in root biology, including root architecture configuration, hormonal responses, nutrient stress adaptation, and meristem cell survival. Biochemical studies and protein sequencing strategies have identified 28 subunits as well as accessory histone acetyltransferases as part of MEDIATOR, which may contribute to DNA relaxing and the opening of promoters for gene expression. The mutation of specific components of MEDIATOR in most cases did not compromise plant survival under standard growth conditions, but rather changes functional processes in a highly specific fashion. Interactions between MEDIATOR, its dissociable kinase module and the TOPLESS repressor underlie the auxin and jasmonic acid response and these phytohormones not only affect MEDIATOR composition, but also its affinity to key transcriptional regulators such as AUXIN RESPONSE FACTORS and MYC2 to cis-acting elements within gene promoters. MEDIATOR also emerges as a master component of the strategies to improve phosphate and iron acquisition, opening new possibilities to manage nutrient stress and plant productivity."

Authors: Yanbiao Sun, Baojun Yang and Bert De Rybel.

Journal of Experimental Botany (2023)

Abstract: "Vascular tissues serve a dual function in plants providing both physical support as well as controlling the transport of nutrients, water, hormones and other small signaling molecules. Xylem tissues transport water from root to shoot; phloem tissues transfer photosynthates from shoot to root; while divisions of the (pro)cambium increase the number of xylem and phloem cells. Although vascular development constitutes a continuous process from primary growth in the early embryo and meristem regions to secondary growth in the mature plant organs, it can be artificially separated into distinct processes including cell type specification, proliferation, patterning and differentiation. In this review, we focus our attention to how hormonal signals orchestrate the molecular regulation of vascular development in the Arabidopsis thaliana primary root meristem. Although auxin and cytokinin have taken center stage in this aspect since their discovery, other hormones including brassinosteroids, abscisic acid and jasmonic acid are also taking up leading roles during vascular development. All these hormonal cues synergistically or antagonistically participate in the development of vascular tissues, forming a complex hormonal control network."

Authors: Mengjia Zhuang, Chaonan Li, Jingyi Wang, Xinguo Mao, Long Li, Jun Yin, Yan Du, Xiang Wang and Ruilian Jing.

Journal of Experimental Botany (2021)

Abstract: "Root is the unique organ of water and nutrients uptake and sensing environmental stimulus in the soil. The optimization of root system architecture contributes to the stress tolerance and yield improvement. ERF (ETHYLENE RESPONSIVE FACTOR) is one of plant specific transcription factor families associated with various developmental processes and stress tolerance. We cloned a novel ERF transcription factor gene TaSRL1 (SHORT ROOT LENGTH 1) from wheat (Triticum aestivum) which is mainly expressed in root. Ectopic expression of TaSRL1 in rice exhibited short root length and plant height. TaSRL1 regulated expression of genes related to auxin synthesis, transport and signaling. Further studies revealed that TaSRL1 induced expression of the auxin transport gene TaPIN2 by directly binding to its promoter, while the interaction of TaSRL1 and TaTIFY9 repressed TaPIN2 expression. Sequence polymorphisms and association analysis showed that TaSRL1-4A was associated with root depth and angle, plant height and 1000-grain weight of wheat. The haplotype Hap-4A-2 with shallow roots, short plant height and high 1000-grain weight has been positively selected in the Chinese wheat breeding process. Therefore, we demonstrated that TaSRL1 functions as a direct regulator of TaPIN2 in the auxin-dependent pathway, and integrates auxin and JA signaling by interacting with TaTIFY9 to repress root growth. Furthermore, the molecular marker of TaSRL1-4A is valuable for the improvement of root system, plant architecture and yield in wheat breeding process.