Are root elongation assays suitable for establishing metallic anion ecotoxicity thresholds?

In urban situations, particularly after construction, herbaceous ornamentals may be planted into soils that are compacted or have poor structure so that plant roots may encounter poor aeration or physical resistance. Low oxygen concentrations may be the most important aspect of poor aeration and are readily reproduced in the laboratory. High atmospheric pressure might be used to screen for the ability to grow against physical resistance. We tested the suggestion that “native” plants would grow better in compacted soils than typical bedding plants and for differences in tolerance to low oxygen or high pressure. Plants were grown from seed in the greenhouse at four levels of compaction in peat-based medium and in field soil. Shoot dry weights of the native plants Asclepias tuberosa, Echinacea purpurea, and Schizachyrium scoparius, were less affected by growth in compacted soil or peat medium than those of the bedding plants, Antirrhinum majus, Gypsophila elegans, Impatiens balsamina, Tagetes patula and Zinnia elegans. The oxygen content of media declined with compaction to a minimum of 10 kPa. Half maximal root elongation was observed at 1 to 3 kPa oxygen for most species without any separation between the groups. A presure of 1100 kPa reduced root elongation of the bedding plants by 50 to 70% but only 5 to 20% for the native plants.

Download Full-text

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

Download Full-text

Rice G protein γ subunit qPE9‐1 modulates root elongation for phosphorus uptake by involving 14‐3‐3 protein OsGF14b and plasma membrane H + ‐ATPase

The Plant Journal ◽

10.1111/tpj.15402 ◽

2021 ◽

Author(s):

Ke Wang ◽

Feiyun Xu ◽

Wei Yuan ◽

Dongping Zhang ◽

Jianping Liu ◽

...

Keyword(s):

Plasma Membrane ◽

G Protein ◽

Root Elongation ◽

Phosphorus Uptake ◽

Γ Subunit

Download Full-text

OsJAZ11 regulates phosphate starvation responses in rice

Planta ◽

10.1007/s00425-021-03657-6 ◽

2021 ◽

Vol 254 (1) ◽

Author(s):

Bipin K. Pandey ◽

Lokesh Verma ◽

Ankita Prusty ◽

Ajit Pal Singh ◽

Malcolm J. Bennett ◽

...

Keyword(s):

Jasmonic Acid ◽

Root Length ◽

Root Elongation ◽

Terminal Region ◽

Physical Interaction ◽

Plant Signaling ◽

Functional Connections ◽

Growth Inhibitory ◽

Expression Studies ◽

Ja Signaling

Abstract Main conclusion OsJAZ11 regulates phosphate homeostasis by suppressing jasmonic acid signaling and biosynthesis in rice roots. Abstract Jasmonic Acid (JA) is a key plant signaling molecule which negatively regulates growth processes including root elongation. JAZ (JASMONATE ZIM-DOMAIN) proteins function as transcriptional repressors of JA signaling. Therefore, targeting JA signaling by deploying JAZ repressors may enhance root length in crops. In this study, we overexpressed JAZ repressor OsJAZ11 in rice to alleviate the root growth inhibitory action of JA. OsJAZ11 is a low phosphate (Pi) responsive gene which is transcriptionally regulated by OsPHR2. We report that OsJAZ11 overexpression promoted primary and seminal root elongation which enhanced Pi foraging. Expression studies revealed that overexpression of OsJAZ11 also reduced Pi starvation response (PSR) under Pi limiting conditions. Moreover, OsJAZ11 overexpression also suppressed JA signaling and biosynthesis as compared to wild type (WT). We further demonstrated that the C-terminal region of OsJAZ11 was crucial for stimulating root elongation in overexpression lines. Rice transgenics overexpressing truncated OsJAZ11ΔC transgene (i.e., missing C-terminal region) exhibited reduced root length and Pi uptake. Interestingly, OsJAZ11 also regulates Pi homeostasis via physical interaction with a key Pi sensing protein, OsSPX1. Our study highlights the functional connections between JA and Pi signaling and reveals JAZ repressors as a promising candidate for improving low Pi tolerance of elite rice genotypes.

Download Full-text

Two Expansin Genes, AtEXPA4 and AtEXPB5, Are Redundantly Required for Pollen Tube Growth and AtEXPA4 Is Involved in Primary Root Elongation in Arabidopsis thaliana

Genes ◽

10.3390/genes12020249 ◽

2021 ◽

Vol 12 (2) ◽

pp. 249

Author(s):

Weimiao Liu ◽

Liai Xu ◽

Hui Lin ◽

Jiashu Cao

Keyword(s):

Arabidopsis Thaliana ◽

Pollen Tube ◽

Pollen Tube Growth ◽

Cell Walls ◽

Root Elongation ◽

Expression Patterns ◽

Primary Root ◽

Pollen Grains ◽

Tube Growth ◽

Cell Wall Binding

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.

Download Full-text

The bacterial volatile N,N-dimethyl-hexadecylamine promotes Arabidopsis primary root elongation through cytokinin signaling and the AHK2 receptor

Plant Signaling & Behavior ◽

10.1080/15592324.2021.1879542 ◽

2021 ◽

Vol 16 (4) ◽

pp. 1879542

Author(s):

Ernesto Vázquez-Chimalhua ◽

Salvador Barrera-Ortiz ◽

Eduardo Valencia-Cantero ◽

José López-Bucio ◽

León Francisco Ruiz-Herrera

Keyword(s):

Root Elongation ◽

Primary Root ◽

Cytokinin Signaling

Download Full-text

Membrane Sterol Composition in Arabidopsis thaliana Affects Root Elongation via Auxin Biosynthesis

International Journal of Molecular Sciences ◽

10.3390/ijms22010437 ◽

2021 ◽

Vol 22 (1) ◽

pp. 437

Author(s):

Meng Wang ◽

Panpan Li ◽

Yao Ma ◽

Xiang Nie ◽

Markus Grebe ◽

...

Keyword(s):

Root Elongation ◽

Auxin Transport ◽

Sterol Composition ◽

Polar Auxin Transport ◽

Sterol Biosynthesis ◽

Auxin Biosynthesis ◽

Root Tip ◽

Auxin Signaling ◽

Auxin Response ◽

Short Root

Plant membrane sterol composition has been reported to affect growth and gravitropism via polar auxin transport and auxin signaling. However, as to whether sterols influence auxin biosynthesis has received little attention. Here, by using the sterol biosynthesis mutant cyclopropylsterol isomerase1-1 (cpi1-1) and sterol application, we reveal that cycloeucalenol, a CPI1 substrate, and sitosterol, an end-product of sterol biosynthesis, antagonistically affect auxin biosynthesis. The short root phenotype of cpi1-1 was associated with a markedly enhanced auxin response in the root tip. Both were neither suppressed by mutations in polar auxin transport (PAT) proteins nor by treatment with a PAT inhibitor and responded to an auxin signaling inhibitor. However, expression of several auxin biosynthesis genes TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS1 (TAA1) was upregulated in cpi1-1. Functionally, TAA1 mutation reduced the auxin response in cpi1-1 and partially rescued its short root phenotype. In support of this genetic evidence, application of cycloeucalenol upregulated expression of the auxin responsive reporter DR5:GUS (β-glucuronidase) and of several auxin biosynthesis genes, while sitosterol repressed their expression. Hence, our combined genetic, pharmacological, and sterol application studies reveal a hitherto unexplored sterol-dependent modulation of auxin biosynthesis during Arabidopsis root elongation.

Download Full-text

SPL14/17 act downstream of strigolactone signalling to modulate rice root elongation in response to nitrate supply

The Plant Journal ◽

10.1111/tpj.15188 ◽

2021 ◽

Author(s):

Huwei Sun ◽

Xiaoli Guo ◽

Xuejiao Qi ◽

Fan Feng ◽

Xiaonan Xie ◽

...

Keyword(s):

Root Elongation ◽

Rice Root ◽

Nitrate Supply ◽

Strigolactone Signalling

Download Full-text

Gasification of Cup Plant (Silphium perfoliatum L.) Biomass–Energy Recovery and Environmental Impacts

Energies ◽

10.3390/en13184960 ◽

2020 ◽

Vol 13 (18) ◽

pp. 4960

Author(s):

Adam Koniuszy ◽

Małgorzata Hawrot-Paw ◽

Cezary Podsiadło ◽

Paweł Sędłak ◽

Ewa Możdżer

Keyword(s):

Environmental Impacts ◽

Root Elongation ◽

Biomass Yield ◽

Plant Biomass ◽

Liquid Waste ◽

Calorific Value ◽

Biomass Energy ◽

Potential Hazard ◽

Gas Generator ◽

Phytotoxic Effect

Biomass from cup plant (Silphium perfoliatum L.) is considered a renewable energy source that can be converted into alternative fuel. Calorific syngas, a promising type of advanced fuel, can be produced through thermochemical biomass gasification. In this study, the suitability of cup plant biomass for gasification was assessed, including the process energy balance and environmental impacts of waste from syngas purification. Silphium perfoliatum L. was cultivated as a gasification feedstock in different conditions (irrigation, fertilization). The experiments were performed in a membrane gasifier. All obtained energy parameters were compared to the biomass yield per hectare. The toxic effects of liquid waste were assessed using tests analyzing germination/seed root elongation of Sinapsis alba. Leachates collected from condensation tanks of a gas generator were introduced to soil at the following doses: 100, 1000 and 10,000 mg kg−1 DM of soil. The usefulness of Silphium perfoliatum L. for gasification was confirmed. The factors of plant cultivation affected the biomass yield, the volume and calorific value of syngas and the amount of biochar. It was determined that the components found in condensates demonstrate a phytotoxic effect, restricting or inhibiting germination and root elongation of Sinapsis alba. Due to this potential hazard, the possibility of its release to the environment should be limited. Most of the biomass is only used for heating purposes, but the syngas obtained from the cup plant can be used to power cogeneration systems, which, apart from heat, also generate electricity.

Download Full-text