 Your new post is loading...
Your new post is loading...
Authors: Kiyoshi Yamazaki, Yoshihiro Ohmori, Hirokazu Takahashi, Atsushi Toyoda, Yutaka Sato, Mikio Nakazono and Toru Fujiwara.
Plant and Cell Physiology (2024)
Abstract: "Nutritropism is a positive tropism toward nutrients in plant roots. An NH4+ gradient is a nutritropic stimulus in rice (Oryza sativa L.). When rice roots are exposed to an NH4+ gradient generated around nutrient sources, root tips bend toward and coil around the sources. The molecular mechanisms are largely unknown. Here, we analyzed the transcriptomes of the inside and outside of bending root tips exhibiting nutritropism to reveal nutritropic signal transduction. Tissues facing the nutrient sources (inside) and away (outside) were separately collected by laser microdissection. Principal component analysis revealed distinct transcriptome patterns between the two tissues. Annotations of 153 differentially expressed genes implied that auxin, gibberellin and ethylene signaling were activated differentially between the sides of the root tips under nutritropism. Exogenous application of transport and/or biosynthesis inhibitors of these phytohormones largely inhibited the nutritropism. Thus, signaling and de novo biosynthesis of the three phytohormones are necessary for nutritropism. Expression patterns of IAA genes implied that auxins accumulated more in the inside tissues, meaning that ammonium stimulus is transduced to auxin signaling in nutritropism similar to gravity stimulus in gravitropism. SAUR and expansin genes, which are known to control cell wall modification and to promote cell elongation in shoot gravitropism, were highly expressed in the inside tissues rather than the outside tissues, and our transcriptome data are unexplainable for differential elongation in root nutritropism."
Authors: Gwendolyn K. Kirschner, Frank Hochholdinger, Silvio Salvi, Malcolm J. Bennett, Guoqiang Huang and Rahul A. Bhosale.
Trends in Plant Science (2024)
Highlights: The root angle in cereals determines soil resource capture, stress resilience, and yield, especially in suboptimal conditions. Root angle regulation involves competing gravitropic and antigravitropic offset mechanisms. Understanding the mechanisms underlying root angle regulation in cereals is important due to their complex root system made up of distinct root types, formed at different stages of development. Recent studies in cereals revealed genes regulating the root angle. However, the precise mechanisms determining and maintaining root angle in distinct root types remain unclear. Understanding the molecular mechanisms underlying root angle control is essential for incorporating the root angle trait into breeding programs.
Abstract: "The root angle plays a critical role in efficiently capturing nutrients and water from different soil layers. Steeper root angles enable access to mobile water and nitrogen from deeper soil layers, whereas shallow root angles facilitate the capture of immobile phosphorus from the topsoil. Thus, understanding the genetic regulation of the root angle is crucial for breeding crop varieties that can efficiently capture resources and enhance yield. Moreover, this understanding can contribute to developing varieties that effectively sequester carbon in deeper soil layers, supporting global carbon mitigation efforts. Here we review and consolidate significant recent discoveries regarding the molecular components controlling root angle in cereal crop species and outline the remaining research gaps in this field."
Authors: Fabrizio Araniti, Emanuela Talarico, Maria Letizia Madeo, Eleonora Greco, Marco Minervino, Sara Álvarez-Rodríguez, Antonella Muto, Michele Ferrari, Adriana Chiappetta and Leonardo Bruno.
Plant Science (2023)
Highlights • Short-term effects of acute Cd toxicity in Arabidopsis and primary targets. • Cd alters starch and sucrose metabolism and the gravitropic root response. • Cd causes a rearrangement and disorganization of the cortical microtubules. • The distribution of auxin efflux carriers is impacted by Cd, in particular PIN2.
Abstract: "Cadmium (Cd), one of the most widespread and water-soluble polluting heavy metals, has been widely studied on plants, even if the mechanisms underlying its phytotoxicity remain elusive. Indeed, most experiments are performed using extensive exposure time to the toxicants, not observing the primary targets affected. The present work studied Cd effects on Arabidopsis thaliana (L.) Heynh’s root apical meristem (RAM) exposed for short periods (24 h and 48 h) to acute phytotoxic concentrations (100 and 150 µM). The effects were studied through integrated morpho-histological, molecular, pharmacological and metabolomic analyses, highlighting that Cd inhibited primary root elongation by affecting the meristem zone via altering cell expansion. Moreover, Cd altered Auxin accumulation in RAM and affected PINs polar transporters, particularly PIN2. In addition, we observed that high Cd concentration induced accumulation of reactive oxygen species (ROS) in roots, which resulted in an altered organization of cortical microtubules and the starch and sucrose metabolism, altering the statolith formation and, consequently, the gravitropic root response. Our results demonstrated that short Cd exposition (24 h) affected cell expansion preferentially, altering auxin distribution and inducing ROS accumulation, which resulted in an alteration of gravitropic response and microtubules orientation pattern."
Authors: Ying Liu and Nicolaus von Wirén.
Current Opinion in Plant Biology (2022)
Abstract: "In most soils, the spatial distribution of nutrients and water in the rooting zone of plants is heterogeneous and changes over time. To access localized resources more efficiently, plants induce foraging responses by modulating individual morphological root traits, such as the length of the primary root or the number and length of lateral roots. These adaptive responses require the integration of exogenous and endogenous nutrient- or water-related signals into the root developmental program. Recent studies corroborated a central role of auxin in shaping root architectural traits in response to fluctuating nutrient and water availabilities. In this review, we highlight current knowledge on nutrient- and water-related developmental processes that impact root foraging and involve auxin as a central player. A deeper understanding and exploitation of these auxin-related processes and mechanisms promises advances in crop breeding for higher resource efficiency."
|
Authors: Ping Yun, Cengiz Kaya and Sergey Shabala.
The Crop Journal (2024)
Abstract: "Salinity stress is a major environmental stress affecting crop productivity, and its negative impact on global food security is only going to increase, due to current climate trends. Salinity tolerance was present in wild crop relatives but significantly weakened during domestication. Regaining it back requires a good understanding of molecular mechanisms and traits involved in control of plant ionic and ROS homeostasis. This review summarizes our current knowledge on the role of major plant hormones (auxin, cytokinins, abscisic acid, salicylic acid, and jasmonate) in plants adaptation to soil salinity. We firstly discuss the role of hormones in controlling root tropisms, root growth and architecture (primary root elongation, meristematic activity, lateral root development, and root hairs formation). Hormone-mediated control of uptake and sequestration of key inorganic ions (sodium, potassium, and calcium) is then discussed followed by regulation of cell redox balance and ROS signaling in salt-stressed roots. Finally, the role of epigenetic alterations such as DNA methylation and histone modifications in control of plant ion and ROS homeostasis and signaling is discussed. This data may help develop novel strategies for breeding and cultivating salt-tolerant crops and improving agricultural productivity in saline regions."
Authors: Hui Wang, Huayang Wang, Houzhou Liu, Tao Wan, Yalin Li, Ketong Zhang, Sergey Shabala, Xuewen Li, Yinglong Chen and Min Yu.
Plant Physiology and Biochemistry (2024)
Highlights • Al stress changed RSA via increasing root GSA of pea. • Exogenous auxin negatively influences the gravitropism of lateral roots by reducing the starch granules in the root tip and changing auxin polar transport. • Al stress changed RSA through the auxin pathway, which is related to the root gravitropic response of plants.
Abstract: "Aluminium (Al) toxicity stands out as a primary cause of crop failure in acidic soils. The root gravity setpoint angle (GSA), one of the important traits of the root system architecture (RSA), plays a pivotal role in enabling plants to adapt to abiotic stress. This study explored the correlation between GSA and Al stress using hydroponic culture with pea (Pisum sativum) plants. The findings revealed that under Al stress, GSA increased in newly developed lateral roots. Notably, this response remained consistent regardless of the treatment duration, extending for at least 3 days during the experiment. Furthermore, exposure to Al led to a reduction in both the size and quantity of starch granules, pivotal components linked to gravity perception. The accumulation of auxin in root transition zone increased. This variation was mirrored in the expression of genes linked to granule formation and auxin efflux, particularly those in the PIN-formed family. This developmental framework suggested a unique role for the root gravitropic response that hinges on starch granules and auxin transport, acting as mediators in the modulation of GSA under Al stress. Exogenous application of indole-3-acetic acid (IAA) and the auxin efflux inhibitor N-1-naphthylphthalamic acid (NPA) had an impact on the root gravitropic response to Al stress. The outcomes indicate that Al stress inhibited polar auxin transport and starch granule formation, the two processes crucial for gravitropism. This impairment led to an elevation in GSA and a reconfiguration of RSA. This study introduces a novel perspective on how plant roots react to Al toxicity, culminating in RSA modification in the context of acidic soil with elevated Al concentrations."
Authors: Dimitris Templalexis, Dikran Tsitsekian, Chen Liu, Gerasimos Daras, Jan Šimura, Panagiotis Moschou, Karin Ljung, Polydefkis Hatzopoulos and Stamatis Rigas.
Plant Physiology (2022)
Abstract: "In plants, auxin transport and development are tightly coupled, just as hormone and growth responses are intimately linked in multicellular systems. Here we provide insights into uncoupling this tight control by specifically targeting the expression of TINY ROOT HAIR 1 (TRH1), a member of plant HAK/KUP/KT transporters that facilitate potassium uptake by co-transporting protons, in Arabidopsis root cell files. Use of this system pinpointed specific root developmental responses to acropetal versus basipetal auxin transport. Loss of TRH1 function shows tiny root hairs and defective root gravitropism, associated with auxin imbalance in the root apex. Cell file-specific expression of TRH1 in the central cylinder rescued trh1 root agravitropism, whereas positional TRH1 expression in peripheral cell layers, including epidermis and cortex, restored trh1 root hair defects. Applying a systems-level approach, the role of RAP2.11 and RSL5 transcription factors in root hair development was verified. Furthermore, ERF53 and WRKY51 transcription factors were overrepresented upon restoration of root gravitropism supporting involvement in gravitropic control. Auxin has a central role in shaping root system architecture by regulating multiple developmental processes. We reveal that TRH1 jointly modulates intracellular ionic gradients and cell-to-cell polar auxin transport to drive root epidermal cell differentiation and gravitropic response. Our results indicate the developmental importance of HAK/KUP/KT proton-coupled K+ transporters.
|
