scholarly journals Control of root system architecture by phytohormones and environmental signals in rice

2020 ◽  
Vol 67 (1-2) ◽  
pp. 98-109
Author(s):  
Chen Lin ◽  
Margret Sauter

Drought and flooding are environmental extremes and major threats to crop production. Water uptake is achieved by plant roots which have to explore new soil spaces to alleviate water deficit during drought or to cope with water excess during flooding. Adaptation of the root system architecture helps plants cope with such extreme conditions and is crucial for plant health and survival. While for dicot plants the well studied model plant Arabidopsis thaliana has provided insight into the genetic and molecular regulation of the root system, less information is available for monocot species, which include the agronomically important cereal crops. Rice (Oryza sativa L.) is a semi-aquatic monocot plant that develops strong tolerance to flooding. Flooding tolerance of rice is closely linked to its adaptive root system. The functional root system of rice is mainly composed of crown roots and is shifted to nodal adventitious roots during flooding which allows rice to maintain oxygen supply to the roots and to survive longer periods of partial submergence as compared with other crops. Likewise, a number of drought-tolerance traits of rice are the result of an altered root system architecture. Hence, the structure of the root system adapts to, both, flooding and drought. Understanding the regulatory mechanisms that control root system adaptation to extreme environments is a key task for scientists to accelerate the breeding efforts for stress-tolerant crops. This review summarizes recently identified genes and molecular mechanisms that regulate root system architecture in rice in response to drought and flooding.

Author(s):  
Nikola Kořínková ◽  
Irene Maria Fontana ◽  
Thu Nguyen ◽  
Pouneh Pouramini ◽  
Véronique Bergougnoux ◽  
...  

Food security is one of the main topics of today’s agriculture especially facing challenging environmental conditions. As most humankind has a daily intake of cereal grains, current breeding programs focus on these crop plants. Within the breeders’ toolbox, customised endonucleases became included after this universal application had been demonstrated. Due to technological restrictions, the main focus was on aboveground plant organs, while the essential belowground has been given only limited attention. In the present review, we summarise the knowledge on the root system architecture in cereals, the importance of phytohormones in this physiological process, and the molecular mechanisms involved. The review summarises how the use of the CRISPR methodology can improve the root system architecture to enhance crop production genetically. Finally, future research directions involving all this knowledge and technical advances are suggested.


2021 ◽  
Author(s):  
Pankaj K Verma ◽  
Shikha Verma ◽  
Nalini Pandey

Abstract BackgroundIn order to feed expanding population, new crop varieties were generated which significantly contribute to world food security. However, the growth of these improved plants varieties relied primarily on synthetic fertilizers, which negatively affect the environment as well as human health. Plants adapt to adverse environmental changes by adopting root systems through architectural changes at the root-type and tissue-specific changes and nutrient uptake efficiency. ScopePlants adapt and operate distinct pathways at various stages of development in order to optimally establish their root systems, such as change in the expression profile of genes, changes in phytohormone level and microbiome induced Root System Architecture (RSA) modification. Many scientific studies have been carried out to understand plant response to microbial colonization and how microbes involved in RSA improvement through phytohormone level and transcriptomic changes.ConclusionIn this review, we spotlight the impact of genes, phytohormones and root microbiota on RSA and provide specific, critical new insights that have been resulted from recent studies on rice root as a model. First, we discuss new insights into the genetic regulation of RSA. Next, hormonal regulation of root architecture and the impact of phytohormones in crown root and root branching is discussed. Finally, we discussed the impact of root microbiota in RSA modification and summarized the current knowledge about the biochemical and central molecular mechanisms involved.


2020 ◽  
Vol 71 (15) ◽  
pp. 4393-4404 ◽  
Author(s):  
Zhongtao Jia ◽  
Nicolaus von Wirén

Abstract Among all essential mineral elements, nitrogen (N) is required in the largest amounts and thus is often a limiting factor for plant growth. N is taken up by plant roots in the form of water-soluble nitrate, ammonium, and, depending on abundance, low-molecular weight organic N. In soils, the availability and composition of these N forms can vary over space and time, which exposes roots to various local N signals that regulate root system architecture in combination with systemic signals reflecting the N nutritional status of the shoot. Uncovering the molecular mechanisms underlying N-dependent signaling provides great potential to optimize root system architecture for the sake of higher N uptake efficiency in crop breeding. In this review, we summarize prominent signaling mechanisms and their underlying molecular players that derive from external N forms or the internal N nutritional status and modulate root development including root hair formation and gravitropism. We also compare the current state of knowledge of these pathways between Arabidopsis and graminaceous plant species.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Shota Teramoto ◽  
Takanari Tanabata ◽  
Yusaku Uga

Abstract Background The root distribution in the soil is one of the elements that comprise the root system architecture (RSA). In monocots, RSA comprises radicle and crown roots, each of which can be basically represented by a single curve with lateral root branches or approximated using a polyline. Moreover, RSA vectorization (polyline conversion) is useful for RSA phenotyping. However, a robust software that can enable RSA vectorization while using noisy three-dimensional (3D) volumes is unavailable. Results We developed RSAtrace3D, which is a robust 3D RSA vectorization software for monocot RSA phenotyping. It manages the single root (radicle or crown root) as a polyline (a vector), and the set of the polylines represents the entire RSA. RSAtrace3D vectorizes root segments between the two ends of a single root. By utilizing several base points on the root, RSAtrace3D suits noisy images if it is difficult to vectorize it using only two end nodes of the root. Additionally, by employing a simple tracking algorithm that uses the center of gravity (COG) of the root voxels to determine the tracking direction, RSAtrace3D efficiently vectorizes the roots. Thus, RSAtrace3D represents the single root shape more precisely than straight lines or spline curves. As a case study, rice (Oryza sativa) RSA was vectorized from X-ray computed tomography (CT) images, and RSA traits were calculated. In addition, varietal differences in RSA traits were observed. The vector data were 32,000 times more compact than raw X-ray CT images. Therefore, this makes it easier to share data and perform re-analyses. For example, using data from previously conducted studies. For monocot plants, the vectorization and phenotyping algorithm are extendable and suitable for numerous applications. Conclusions RSAtrace3D is an RSA vectorization software for 3D RSA phenotyping for monocots. Owing to the high expandability of the RSA vectorization and phenotyping algorithm, RSAtrace3D can be applied not only to rice in X-ray CT images but also to other monocots in various 3D images. Since this software is written in Python language, it can be easily modified and will be extensively applied by researchers in this field.


2019 ◽  
Vol 3 (2) ◽  
pp. 102-111 ◽  
Author(s):  
Chakradhar Mattupalli ◽  
Anand Seethepalli ◽  
Larry M. York ◽  
Carolyn A. Young

Root system architecture is critical for plant growth, which is influenced by several edaphic, environmental, genetic, and biotic factors including beneficial and pathogenic microbes. Studying root system architecture and the dynamic changes that occur during a plant’s lifespan, especially for perennial crops growing over multiple growing seasons, is still a challenge because of the nature of their growing environment. We describe the utility of an imaging platform called RhizoVision Crown to study root system architecture of alfalfa, a perennial forage crop threatened by Phymatotrichopsis root rot (PRR) disease. Phymatotrichopsis omnivora is the causal agent of PRR disease that reduces alfalfa stand longevity. During the lifetime of the stand, PRR disease rings enlarge and the field can be categorized into three zones based upon plant status: asymptomatic, disease front and survivor. To study root system architectural changes associated with PRR, a 4-year-old 25.6-ha alfalfa stand infested with PRR was selected at the Red River Farm, Burneyville, OK during October 2017. Line transect sampling was conducted from four actively growing PRR disease rings. At each disease ring, six line transects were positioned spanning 15 m on either side of the disease front with one alfalfa root crown sampled at every 3 m interval. Each alfalfa root crown was imaged with the RhizoVision Crown platform using a backlight and a high-resolution monochrome CMOS camera enabling preservation of the natural root system integrity. The platform’s image analysis software, RhizoVision Analyzer, automatically segmented images, skeletonized, and extracted a suite of features. Data indicated that the survivor plants compensated for damage or loss to the taproot through the development of more lateral and crown roots, and that a suite of multivariate features could be used to automatically classify roots as from survivor or asymptomatic zones. Root growth is a dynamic process adapting to ever changing interactions among various phytobiome components. By utilizing the low-cost, efficient, and high-throughput RhizoVision Crown platform, we quantified these changes in a mature perennial forage crop.


2015 ◽  
Vol 112 (21) ◽  
pp. 6754-6759 ◽  
Author(s):  
Caroline Gutjahr ◽  
Ruairidh J. H. Sawers ◽  
Guillaume Marti ◽  
Liliana Andrés-Hernández ◽  
Shu-Yi Yang ◽  
...  

Root systems consist of different root types (RTs) with distinct developmental and functional characteristics. RTs may be individually reprogrammed in response to their microenvironment to maximize adaptive plasticity. Molecular understanding of such specific remodeling—although crucial for crop improvement—is limited. Here, RT-specific transcriptomes of adult rice crown, large and fine lateral roots were assessed, revealing molecular evidence for functional diversity among individual RTs. Of the three rice RTs, crown roots displayed a significant enrichment of transcripts associated with phytohormones and secondary cell wall (SCW) metabolism, whereas lateral RTs showed a greater accumulation of transcripts related to mineral transport. In nature, arbuscular mycorrhizal (AM) symbiosis represents the default state of most root systems and is known to modify root system architecture. Rice RTs become heterogeneously colonized by AM fungi, with large laterals preferentially entering into the association. However, RT-specific transcriptional responses to AM symbiosis were quantitatively most pronounced for crown roots despite their modest physical engagement in the interaction. Furthermore, colonized crown roots adopted an expression profile more related to mycorrhizal large lateral than to noncolonized crown roots, suggesting a fundamental reprogramming of crown root character. Among these changes, a significant reduction in SCW transcripts was observed that was correlated with an alteration of SCW composition as determined by mass spectrometry. The combined change in SCW, hormone- and transport-related transcript profiles across the RTs indicates a previously overlooked switch of functional relationships among RTs during AM symbiosis, with a potential impact on root system architecture and functioning.


2020 ◽  
Vol 21 (17) ◽  
pp. 5955 ◽  
Author(s):  
Guoqiang Huang ◽  
Dabing Zhang

Phosphate is an essential macro-element for plant growth accumulated in the topsoil. The improvement of phosphate uptake efficiency via manually manipulating root system architecture is of vital agronomic importance. This review discusses the molecular mechanisms of root patterning in response to external phosphate availability, which could be applied on the alleviation of phosphate-starvation stress. During the long time evolution, plants have formed sophisticated mechanisms to adapt to environmental phosphate conditions. In terms of root systems, plants would adjust their root system architecture via the regulation of the length of primary root, the length/density of lateral root and root hair and crown root growth angle to cope with different phosphate conditions. Finally, plants develop shallow or deep root system in low or high phosphate conditions, respectively. The plasticity of root system architecture responds to the local phosphate concentrations and this response was regulated by actin filaments, post-translational modification and phytohormones such as auxin, ethylene and cytokinin. This review summarizes the recent progress of adaptive response to external phosphate with focus on integrated physiological, cellular and molecular signaling transduction in rice and Arabidopsis.


2020 ◽  
Vol 11 ◽  
Author(s):  
Waldiodio Seck ◽  
Davoud Torkamaneh ◽  
François Belzile

Increasing the understanding genetic basis of the variability in root system architecture (RSA) is essential to improve resource-use efficiency in agriculture systems and to develop climate-resilient crop cultivars. Roots being underground, their direct observation and detailed characterization are challenging. Here, were characterized twelve RSA-related traits in a panel of 137 early maturing soybean lines (Canadian soybean core collection) using rhizoboxes and two-dimensional imaging. Significant phenotypic variation (P < 0.001) was observed among these lines for different RSA-related traits. This panel was genotyped with 2.18 million genome-wide single-nucleotide polymorphisms (SNPs) using a combination of genotyping-by-sequencing and whole-genome sequencing. A total of 10 quantitative trait locus (QTL) regions were detected for root total length and primary root diameter through a comprehensive genome-wide association study. These QTL regions explained from 15 to 25% of the phenotypic variation and contained two putative candidate genes with homology to genes previously reported to play a role in RSA in other species. These genes can serve to accelerate future efforts aimed to dissect genetic architecture of RSA and breed more resilient varieties.


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