Association of Barley Root Elongation with ABA-Dependent Transport of Cytokinins from Roots and Shoots under Supra-Optimal Concentrations of Nitrates and Phosphates

Changes in root elongation are important for the acquisition of mineral nutrients by plants. Plant hormones, cytokinins, and abscisic acid (ABA) and their interaction are important for the control of root elongation under changes in the availability of ions. However, their role in growth responses to supra-optimal concentrations of nitrates and phosphates has not been sufficiently studied and was addressed in the present research. Effects of supra-optimal concentrations of these ions on root elongation and distribution of cytokinins between roots and shoots were studied in ABA-deficient barley mutant Az34 and its parental variety, Steptoe. Cytokinin concentration in the cells of the growing root tips was analyzed with the help of an immunohistochemical technique. Increased concentrations of nitrates and phosphates led to the accumulation of ABA and cytokinins in the root tips, accompanied by a decline in shoot cytokinin content and inhibition of root elongation in Steptoe. Neither of the effects were detected in Az34, suggesting the importance of the ability of plants to accumulate ABA for the control of these responses. Since cytokinins are known to inhibit root elongation, the effect of supra-optimal concentration of nitrates and phosphates on root growth is likely to be due to the accumulation of cytokinins brought about by ABA-induced inhibition of cytokinin transport from roots to shoots.

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Effect of aluminium on root elongation in two Australian perennial grasses

Functional Plant Biology ◽

10.1071/pp97134 ◽

1998 ◽

Vol 25 (2) ◽

pp. 165 ◽

Cited By ~ 7

Author(s):

Simon A. Crawford ◽

Sabine Wilkens

Keyword(s):

Root Growth ◽

Root Elongation ◽

Root Apex ◽

Perennial Grasses ◽

Root Tips ◽

Al Stress ◽

Control Growth ◽

Hematoxylin Staining ◽

Inhibition Of Root Elongation ◽

Nutrient Solutions

Inhibition of net root elongation and patterns of hematoxylin staining were used to assess relative tolerance to phytotoxic Al in Danthonia linkii Kunth and Microlaena stipoides (Labill.) R.Br. According to net root elongation, M. stipoides is significantly more tolerant of phytotoxic Al than D. linkii. In nutrient solutions with Al concentrations of 370 µM and higher, root elongation is stopped in D. linkii after 24 h while in M. stipoides root elongation is maintained at 60–70% of control rates over 72 h. After removal of Al-stress, root growth in M. stipoides from all Al-treatments recovered to be at or above control growth after 72 h. In D. linkii, root elongation in plants exposed to Al levels that caused a reduction in growth (<370 µM), but not complete cessation, recovered after removal of Al stress. Greater intensities of hematoxylin staining were seen in Al-stressed root tips of D. linkii compared to M. stipoides, suggesting that inhibition of root elongation is associated with increased accumulation of Al in root tips. Roots of M. stipoides seedlings exposed to all Al-treatments showed a short band of intensely stained tissue, correlating with the position of the root apex at the exact point of initial Al- exposure. New root growth after this band did not stain with hematoxylin, indicating activation of a mechanism of Al-exclusion in roots of M. stipoides.

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Genome-wide identification and transcriptional analyses of MATE transporter genes in root tips of wild Cicer spp. under aluminium stress

10.1101/2020.04.27.063065 ◽

2020 ◽

Cited By ~ 1

Author(s):

Xia Zhang ◽

Brayden Weir ◽

Hongru Wei ◽

Zhiwei Deng ◽

Xiaoqi Zhang ◽

...

Keyword(s):

Root Growth ◽

Root Elongation ◽

Transcriptional Profiling ◽

Functional Characterization ◽

Relative Reduction ◽

Root Tips ◽

Al Tolerance ◽

Genome Wide ◽

Encoding Genes ◽

Al Treatment

AbstractChickpea is an economically important legume crop with high nutritional value in human diets. Aluminium-toxicity poses a significant challenge for the yield improvement of this increasingly popular crop in acidic soils. The wild progenitors of chickpea may provide a more diverse gene pool for Al-tolerance in chickpea breeding. However, the genetic basis of Al-tolerance in chickpea and its wild relatives remains largely unknown. Here, we assessed the Al-tolerance of six selected wild Cicer accessions by measuring the root elongation in solution culture under control (0 µM Al3+) and Al-treatment (30 µM Al3+) conditions. Al-treatment significantly reduced the root elongation in all target lines compared to the control condition after 2-day’s growth. However, the relative reduction of root elongation in different lines varied greatly: 3 lines still retained significant root growth under Al-treatment, whilst another 2 lines displayed no root growth at all. We performed genome-wide identification of multidrug and toxic compound extrusion (MATE) encoding genes in the Cicer genome. A total of 56 annotated MATE genes were identified, which divided into 4 major phylogeny groups (G1-4). Four homologues to lupin LaMATE (> 50% aa identity; named CaMATE1-4) were clustered with previously characterised MATEs related to Al-tolerance in various other plants. qRT-PCR showed that CaMATE2 transcription in root tips was significantly up-regulated upon Al-treatment in all target lines, whilst CaMATE1 was up-regulated in all lines except Bari2_074 and Deste_064, which coincided with the lines displaying no root growth under Al-treatment. Transcriptional profiling in five Cicer tissues revealed that CaMATE1 is specifically transcribed in the root tissue, further supporting its role in Al-detoxification in roots. This first identification of MATE-encoding genes associated with Al-tolerance in Cicer paves the ways for future functional characterization of MATE genes in Cicer spp., and to facilitate future design of gene-specific markers for Al-tolerant line selection in chickpea breeding programs.

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Effects of Phosphate Shortage on Root Growth and Hormone Content of Barley Depend on Capacity of the Roots to Accumulate ABA

Plants ◽

10.3390/plants9121722 ◽

2020 ◽

Vol 9 (12) ◽

pp. 1722

Author(s):

Lidiya Vysotskaya ◽

Guzel Akhiyarova ◽

Arina Feoktistova ◽

Zarina Akhtyamova ◽

Alla Korobova ◽

...

Keyword(s):

Root Growth ◽

Lateral Roots ◽

Primary Root ◽

Growth Responses ◽

Root Tips ◽

P Deficiency ◽

Root Branching ◽

Auxin Concentration ◽

Shoot Mass ◽

Primary Root Length

Although changes in root architecture in response to the environment can optimize mineral and water nutrient uptake, mechanisms regulating these changes are not well-understood. We investigated whether P deprivation effects on root development are mediated by abscisic acid (ABA) and its interactions with other hormones. The ABA-deficient barley mutant Az34 and its wild-type (WT) were grown in P-deprived and P-replete conditions, and hormones were measured in whole roots and root tips. Although P deprivation decreased growth in shoot mass similarly in both genotypes, only the WT increased primary root length and number of lateral roots. The effect was accompanied by ABA accumulation in root tips, a response not seen in Az34. Increased ABA in P-deprived WT was accompanied by decreased concentrations of cytokinin, an inhibitor of root extension. Furthermore, P-deficiency in the WT increased auxin concentration in whole root systems in association with increased root branching. In the ABA-deficient mutant, P-starvation failed to stimulate root elongation or promote branching, and there was no decline in cytokinin and no increase in auxin. The results demonstrate ABA’s ability to mediate in root growth responses to P starvation in barley, an effect linked to its effects on cytokinin and auxin concentrations.

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In situ laser manipulation of root tissues in transparent soil

Plant and Soil ◽

10.1007/s11104-021-05133-2 ◽

2021 ◽

Author(s):

Sisi Ge ◽

Lionel X. Dupuy ◽

Michael P. MacDonald

Keyword(s):

Root Growth ◽

Root Elongation ◽

Plant Roots ◽

Growth Responses ◽

Light Power ◽

Transparent Soil ◽

Laser Manipulation ◽

Set Up ◽

Root Tissues

Abstract Aims Laser micromanipulation such as dissection or optical trapping enables remote physical modification of the activity of tissues, cells and organelles. To date, applications of laser manipulation to plant roots grown in soil have been limited. Here, we show laser manipulation can be applied in situ when plant roots are grown in transparent soil. Methods We have developed a Q-switched laser manipulation and imaging instrument to perform controlled dissection of roots and to study light-induced root growth responses. We performed a detailed characterisation of the properties of the cutting beams through the soil, studying dissection and optical ablation. Furthermore, we also studied the use of low light doses to control the root elongation rate of lettuce seedlings (Lactuca sativa) in air, agar, gel and transparent soil. Results We show that whilst soil inhomogeneities affect the thickness and circularity of the beam, those distortions are not inherently limiting. The ability to induce changes in root elongation or complete dissection of microscopic regions of the root is robust to substrate heterogeneity and microscopy set up and is maintained following the limited distortions induced by the transparent soil environment. Conclusions Our findings show that controlled in situ laser dissection of root tissues is possible with a simple and low-cost optical set-up. We also show that, in the absence of dissection, a reduced laser light power density can provide reversible control of root growth, achieving a precise “point and shoot” method for root manipulation.

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Inhibition of Downy Brome (Bromus tectorum) Root Growth by a Phytotoxin fromPseudomonas fluorescensStrain D7

Weed Technology ◽

10.1017/s0890037x00037003 ◽

1993 ◽

Vol 7 (1) ◽

pp. 134-139 ◽

Cited By ~ 29

Author(s):

Patrick J. Tranel ◽

David R. Gealy ◽

Ann C. Kennedy

Keyword(s):

Root Growth ◽

Root Elongation ◽

Bromus Tectorum ◽

Downy Brome ◽

Hydroponic System ◽

Crude Preparation ◽

Inhibit Root Growth ◽

Petri Plate ◽

Inhibition Of Root Elongation ◽

Plate System

Field applications of the rhizobacterium,Pseudomonas fluorescensstrain D7 (D7), have selectively suppressed downy brome in winter wheat test plots. A phytotoxin produced by D7 inhibits downy brome root growth. An assay system was developed for future investigations of the mechanism of action of this and other phytotoxins that inhibit root growth. A crude preparation of the phytotoxin, cell-free supernatant (CFS), had little activity on downy brome root elongation in a sand-petri plate system. CFS was very active in a hydroponic system, in which a 6% (v/v) concentration inhibited root elongation within 1.5 h. Inhibition of root elongation was reversible in this system. Root elongation of downy brome seedlings resumed within 3 h after removal from a 9-h incubation in 8% CFS. CFS from genetic variants of D7 did not substantially inhibit root growth and a semi-crystallized precipitation product from D7 CFS inhibited root growth similarly to D7 CFS, indicating that the phytotoxin present in the CFS was responsible for growth inhibition.

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Role of Ascorbate in the Regulation of the Arabidopsis thaliana Root Growth by Phosphate Availability

Journal of Botany ◽

10.1155/2012/580342 ◽

2012 ◽

Vol 2012 ◽

pp. 1-11 ◽

Cited By ~ 12

Author(s):

Jarosław Tyburski ◽

Kamila Dunajska-Ordak ◽

Monika Skorupa ◽

Andrzej Tretyn

Keyword(s):

Root Growth ◽

Lateral Root ◽

Root Elongation ◽

Lateral Roots ◽

Primary Root ◽

Root Hairs ◽

P Availability ◽

Root Tips ◽

P Deficiency ◽

Phosphate Availability

Arabidopsis root system responds to phosphorus (P) deficiency by decreasing primary root elongation and developing abundant lateral roots. Feeding plants with ascorbic acid (ASC) stimulated primary root elongation in seedlings grown under limiting P concentration. However, at high P, ASC inhibited root growth. Seedlings of ascorbate-deficient mutant (vtc1) formed short roots irrespective of P availability. P-starved plants accumulated less ascorbate in primary root tips than those grown under high P. ASC-treatment stimulated cell divisions in root tips of seedlings grown at low P. At high P concentrations ASC decreased the number of mitotic cells in the root tips. The lateral root density in seedlings grown under P deficiency was decreased by ASC treatments. At high P, this parameter was not affected by ASC-supplementation. vtc1 mutant exhibited increased lateral root formation on either, P-deficient or P-sufficient medium. Irrespective of P availability, high ASC concentrations reduced density and growth of root hairs. These results suggest that ascorbate may participate in the regulation of primary root elongation at different phosphate availability via its effect on mitotic activity in the root tips.

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Two ecotype-related long non-coding RNAs in the environmental control of root growth

10.1101/579656 ◽

2019 ◽

Cited By ~ 2

Author(s):

Thomas Blein ◽

Coline Balzergue ◽

Thomas Roulé ◽

Marc Gabriel ◽

Laetitia Scalisi ◽

...

Keyword(s):

Root Growth ◽

Environmental Control ◽

Primary Root ◽

Phosphate Starvation ◽

Differentially Expressed ◽

Growth Responses ◽

Root Tips ◽

Antisense Rnas ◽

Primary Root Growth ◽

Non Coding Rnas

AbstractBackgroundRoot architecture varies widely between species and even between ecotypes of the same species despite the strong conservation of the protein-coding portion of their genomes. In contrast, non-coding RNAs evolved rapidly between ecotypes and may control their differential responses to the environment as several long non-coding RNAs (lncRNAs) can quantitatively regulate gene expression.ResultsRoots from Columbia (Col) and Landsbergerecta(Ler) ecotypes respond differently to phosphate starvation. We compared complete transcriptomes (mRNAs, lncRNAs and small RNAs) of root tips from these two ecotypes during early phosphate starvation. We identified thousands of new lncRNAs categorized as intergenic or antisense RNAs that were largely conserved at DNA level in these ecotypes. In contrast to coding genes, many lncRNAs were specifically transcribed in one ecotype and/or differentially expressed between ecotypes independently of the phosphate condition. These ecotype-related lncRNAs were characterized by analyzing their sequence variability among plants and their link with siRNAs. Our analysis identified 675 lncRNAs differentially expressed between the two ecotypes including specific antisense RNAs targeting key regulators of root growth responses. Mis-regulation of several intergenic lncRNAs showed that at least two ecotype-related lncRNAs regulate primary root growth in Col.ConclusionsThe in depth exploration of the non-coding transcriptome of two ecotypes identified thousands of new lncRNAs showing specific expression in root apexes. De-regulation of two ecotype-related lncRNAs revealed a new pathway involved in the regulation of primary root growth. The non-coding genome may reveal novel mechanisms involved in ecotype adaptation of roots to different soil environments.

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Primary Root Elongation Rate and Abscisic Acid Levels of Maize in Response to Water Stress

Crop Science ◽

10.2135/cropsci2009.12.0708 ◽

2011 ◽

Vol 51 (1) ◽

pp. 157-172 ◽

Cited By ~ 16

Author(s):

Kristen A. Leach ◽

Lindsey G. Hejlek ◽

Leonard B. Hearne ◽

Henry T. Nguyen ◽

Robert E. Sharp ◽

...

Keyword(s):

Abscisic Acid ◽

Water Stress ◽

Root Elongation ◽

Primary Root ◽

Elongation Rate ◽

Root Elongation Rate ◽

Response To Water

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Impact of Mycorrhization on Phosphorus Utilization Efficiency of Acacia gummifera and Retama monosperma under Salt Stress

Forests ◽

10.3390/f12050611 ◽

2021 ◽

Vol 12 (5) ◽

pp. 611

Author(s):

Abdessamad Fakhech ◽

Martin Jemo ◽

Najat Manaut ◽

Lahcen Ouahmane ◽

Mohamed Hafidi

Keyword(s):

Salt Stress ◽

Root Growth ◽

N Uptake ◽

P Uptake ◽

Utilization Efficiency ◽

Legume Species ◽

Growth Responses ◽

Phosphorus Utilization ◽

Phosphorus Utilization Efficiency ◽

Shoot And Root Growth

The impact of salt stress on the growth and phosphorus utilization efficiency (PUE) of two leguminous species: Retama monosperma and Acacia gummifera was studied. The effectiveness of arbuscular mycorrhizal fungi (AMF) to mitigate salt stress was furthermore assessed. Growth, N and P tissue concentrations, mycorrhizal root colonization frequency and intensity, and P utilization efficiency (PUE) in the absence or presence of AMF were evaluated under no salt (0 mM L−1) and three salt (NaCl) concentrations of (25, 50 and 100 mM L−1) using a natural sterilized soil. A significant difference in mycorrhizal colonization intensity, root-to-shoot ratio, P uptake, PUE, and N uptake was observed between the legume species. Salt stress inhibited the shoot and root growth, and reduced P and N uptake by the legume species. Mycorrhizal inoculation aided to mitigate the effects of salt stress with an average increase of shoot and root growth responses by 35% and 32% in the inoculated than in the non-inoculated A. gummifera treatments. The average shoot and root growth responses were 37% and 45% higher in the inoculated compared to the non-inoculated treatments of R. monosperma. Average mycorrhizal shoot and root P uptake responses were 66% and 68% under A. gummifera, and 40% and 95% under R. monosperma, respectively. Mycorrhizal inoculated treatments consistently maintained lower PUE in the roots. The results provide insights for further investigations on the AMF conferred mechanisms to salt stress tolerance response by A. gummifera and R. monosperma, to enable the development of effective technologies for sustainable afforestation and reforestation programs in the Atlantic coast of Morocco.

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