Endogenous Polyamines and Ethylene Biosynthesis in Relation to Germination of Osmoprimed Brassica napus Seeds under Salt Stress

Currently, seed priming is reported as an efficient and low-cost approach to increase crop yield, which could not only promote seed germination and improve plant growth state but also increase abiotic stress tolerance. Salinity represents one of the most significant abiotic stresses that alters multiple processes in plants. The accumulation of polyamines (PAs) in response to salt stress is one of the most remarkable plant metabolic responses. This paper examined the effect of osmopriming on endogenous polyamine metabolism at the germination and early seedling development of Brassica napus in relation to salinity tolerance. Free, conjugated and bound polyamines were analyzed, and changes in their accumulation were discussed with literature data. The most remarkable differences between the corresponding osmoprimed and unprimed seeds were visible in the free (spermine) and conjugated (putrescine, spermidine) fractions. The arginine decarboxylase pathway seems to be responsible for the accumulation of PAs in primed seeds. The obvious impact of seed priming on tyramine accumulation was also demonstrated. Moreover, the level of ethylene increased considerably in seedlings issued from primed seeds exposed to salt stress. It can be concluded that the polyamines are involved in creating the beneficial effect of osmopriming on germination and early growth of Brassica napus seedlings under saline conditions through moderate changes in their biosynthesis and accumulation.

Download Full-text

Enhancement of Brassica napus Tolerance to High Saline Conditions by Seed Priming

Plants ◽

10.3390/plants10020403 ◽

2021 ◽

Vol 10 (2) ◽

pp. 403

Author(s):

Panaiotis M. Stassinos ◽

Massimiliano Rossi ◽

Ilaria Borromeo ◽

Concetta Capo ◽

Simone Beninati ◽

...

Keyword(s):

Salt Stress ◽

Stress Response ◽

Brassica Napus ◽

Photosynthetic Pigments ◽

Membrane Integrity ◽

Seed Priming ◽

Crop Productivity ◽

Saline Stress ◽

Salt Stress Response ◽

Positive Effects

Plants grown in saline soils undergo osmotic and oxidative stresses, affecting growth and photosynthesis and, consequently, the yield. Therefore, the increase in soil salinity is a major threat to crop productivity worldwide. Plant’s tolerance can be ameliorated by applying simple methods that induce them to adopt morphological and physiological adjustments to counteract stress. In this work, we evaluated the effects of seed priming on salt stress response in three cultivars of rapeseed (Brassica napus L.) that had different tolerance levels. Seed chemical priming was performed with 2.5 mM spermine (SPM), 5 mM spermidine (SPD), 40 mM NaCl and 2.5 mM Ca (NO3)2. Primed and not primed seeds were sown on saline and not saline (controls) media, and morphological and physiological parameters were determined. Since SPD treatment was effective in reducing salinity negative effects on growth, membrane integrity and photosynthetic pigments, we selected this priming to further investigate plant salt stress response. The positive effects of this seed treatment on growth and physiological responses were evident when primed plants were compared to not primed ones, grown under the same saline conditions. SPD priming ameliorated the tolerance towards saline stress, in a genotype-independent manner, by increasing photosynthetic pigments, proline amounts and antioxidant responses in all cultivars exposed to salt. These results may open new perspectives for crop productivity in the struggle against soil salinization.

Download Full-text

Using seed respiration as a tool for calculating optimal soaking times for ‘on-farm’ seed priming of barley (Hordeum vulgare)

Seed Science Research ◽

10.1017/s0960258521000039 ◽

2021 ◽

pp. 1-9

Author(s):

Javier Carrillo-Reche ◽

Adrian C. Newton ◽

Richard S. Quilliam

Keyword(s):

Morphological Changes ◽

Low Cost ◽

Germination Rate ◽

Seed Priming ◽

Embryonic Axes ◽

Seedling Vigour ◽

Soaking Time ◽

On Farm ◽

Seed Respiration

Abstract A low-cost technique named ‘on-farm’ seed priming is increasingly being recognized as an effective approach to maximize crop establishment. It consists of anaerobically soaking seeds in water before sowing resulting in rapid and uniform germination, and enhanced seedling vigour. The extent of these benefits depends on the soaking time. The current determination of optimal soaking time by germination assays and mini-plot trials is resource-intensive, as it is species/genotype-specific. This study aimed to determine the potential of the seed respiration rate (an indicator of metabolic activity) and seed morphological changes during barley priming as predictors of the priming benefits and, thus, facilitate the determination of optimal soaking times. A series of germination tests revealed that the germination rate is mostly attributable to the rapid hydration of embryo tissues, as the highest gains in the germination rate occurred before the resumption of respiration. Germination uniformity, however, was not significantly improved until seeds were primed for at least 8 h, that is, after a first respiration burst was initiated. The maximum seedling vigour was attained when the priming was stopped just before the beginning of the differentiation of embryonic axes (20 h) after which vigour began to decrease (‘over-priming’). The onset of embryonic axis elongation was preceded by a second respiration burst, which can be used as a marker for priming optimization. Thus, monitoring of seed respiration provides a rapid and inexpensive alternative to the current practice. The method could be carried out by agricultural institutions to provide recommended optimal soaking times for the common barley varieties within a specific region.

Download Full-text

Zinc Seed Priming Improves Spinach Germination at Low Temperature

Agriculture ◽

10.3390/agriculture11030271 ◽

2021 ◽

Vol 11 (3) ◽

pp. 271

Author(s):

Muhammad Imran ◽

Asim Mahmood ◽

Günter Neumann ◽

Birte Boelt

Keyword(s):

Low Temperature ◽

Temperature Stress ◽

Multispectral Imaging ◽

Germination Rate ◽

Cost Effective ◽

Seed Priming ◽

Seedling Development ◽

Low Temperature Stress ◽

Early Seedling ◽

Early Seedling Development

Low temperature during germination hinders germination speed and early seedling development. Zn seed priming is a useful and cost-effective tool to improve germination rate and resistance to low temperature stress during germination and early seedling development. Spinach was tested to improve germination and seedling development with Zn seed priming under low temperature stress conditions. Zn priming increased seed Zn concentration up to 48 times. The multispectral imaging technique with VideometerLab was used as a non-destructive method to differentiate unprimed, water- and Zn-primed spinach seeds successfully. Localization of Zn in the seeds was studied using the 1,5-diphenyl thiocarbazone (DTZ) dying technique. Active translocation of primed Zn in the roots of young seedlings was detected with laser confocal microscopy. Zn priming of spinach seeds at 6 mM Zn showed a significant increase in germination rate and total germination under low temperature at 8 °C.

Download Full-text

Enhanced Abiotic Stress Tolerance of Vicia faba L. Plants Heterologously Expressing the PR10a Gene from Potato

Plants ◽

10.3390/plants10010173 ◽

2021 ◽

Vol 10 (1) ◽

pp. 173

Author(s):

Abeer F. Desouky ◽

Ahmed H. Ahmed ◽

Hartmut Stützel ◽

Hans-Jörg Jacobsen ◽

Yi-Chen Pao ◽

...

Keyword(s):

Salt Stress ◽

Abiotic Stress ◽

Stress Tolerance ◽

Vicia Faba ◽

Faba Bean ◽

Abiotic Stress Tolerance ◽

Wild Type ◽

Stress Injury ◽

Bean Plants ◽

Vicia Faba L

Pathogenesis-related (PR) proteins are known to play relevant roles in plant defense against biotic and abiotic stresses. In the present study, we characterize the response of transgenic faba bean (Vicia faba L.) plants encoding a PR10a gene from potato (Solanum tuberosum L.) to salinity and drought. The transgene was under the mannopine synthetase (pMAS) promoter. PR10a-overexpressing faba bean plants showed better growth than the wild-type plants after 14 days of drought stress and 30 days of salt stress under hydroponic growth conditions. After removing the stress, the PR10a-plants returned to a normal state, while the wild-type plants could not be restored. Most importantly, there was no phenotypic difference between transgenic and non-transgenic faba bean plants under well-watered conditions. Evaluation of physiological parameters during salt stress showed lower Na+-content in the leaves of the transgenic plants, which would reduce the toxic effect. In addition, PR10a-plants were able to maintain vegetative growth and experienced fewer photosystem changes under both stresses and a lower level of osmotic stress injury under salt stress compared to wild-type plants. Taken together, our findings suggest that the PR10a gene from potato plays an important role in abiotic stress tolerance, probably by activation of stress-related physiological processes.

Download Full-text

Polyamine Metabolism in Scots Pine Embryogenic Cells under Potassium Deficiency

Cells ◽

10.3390/cells10051244 ◽

2021 ◽

Vol 10 (5) ◽

pp. 1244

Author(s):

Riina Muilu-Mäkelä ◽

Jaana Vuosku ◽

Hely Häggman ◽

Tytti Sarjala

Keyword(s):

Scots Pine ◽

Culture Medium ◽

Developmental Regulation ◽

Cell Mass ◽

Arginine Decarboxylase ◽

Protective Role ◽

Potassium Deficiency ◽

Polyamine Metabolism ◽

Embryogenic Cells ◽

Embryogenic Cell

Polyamines (PA) have a protective role in maintaining growth and development in Scots pine during abiotic stresses. In the present study, a controlled liquid Scots pine embryogenic cell culture was used for studying the responses of PA metabolism related to potassium deficiency. The transcription level regulation of PA metabolism led to the accumulation of putrescine (Put). Arginine decarboxylase (ADC) had an increased expression trend under potassium deficiency, whereas spermidine synthase (SPDS) expression decreased. Generally, free spermidine (Spd) and spermine (Spm)/ thermospermine (t-Spm) contents were kept relatively stable, mostly by the downregulation of polyamine oxidase (PAO) expression. The low potassium contents in the culture medium decreased the potassium content of the cells, which inhibited cell mass growth, but did not affect cell viability. The reduced growth was probably caused by repressed metabolic activity and cell division, whereas there were no signs of H2O2-induced oxidative stress or increased cell death. The low intracellular content of K+ decreased the content of Na+. The decrease in the pH of the culture medium indicated that H+ ions were pumped out of the cells. Altogether, our findings emphasize the specific role(s) of Put under potassium deficiency and strict developmental regulation of PA metabolism in Scots pine.

Download Full-text

Overexpression of arginine decarboxylase in transgenic plants

Biochemical Journal ◽

10.1042/bj3250331 ◽

1997 ◽

Vol 325 (2) ◽

pp. 331-337 ◽

Cited By ~ 46

Author(s):

Daniel BURTIN ◽

Anthony J. MICHAEL

Keyword(s):

Transgenic Plants ◽

Arginine Decarboxylase ◽

Polyamine Metabolism ◽

Morphological Development ◽

Polyamine Biosynthesis ◽

Adenosylmethionine Decarboxylase ◽

Two Generations ◽

Key Enzyme ◽

Polyamine Conjugate ◽

And Control

The activity of arginine decarboxylase (ADC), a key enzyme in plant polyamine biosynthesis, was manipulated in two generations of transgenic tobacco plants. Second-generation transgenic plants overexpressing an oat ADC cDNA contained high levels of oat ADC transcript relative to tobacco ADC, possessed elevated ADC enzyme activity and accumulated 10–20-fold more agmatine, the direct product of ADC. In the presence of high levels of the precursor agmatine, no increase in the levels of the polyamines putrescine, spermidine and spermine was detected in the transgenic plants. Similarly, the activities of ornithine decarboxylase and S-adenosylmethionine decarboxylase were unchanged. No diversion of polyamine metabolism into the hydroxycinnamic acid–polyamine conjugate pool or into the tobacco alkaloid nicotine was detected. Activity of the catabolic enzyme diamine oxidase was the same in transgenic and control plants. The elevated ADC activity and agmatine production were subjected to a metabolic/physical block preventing increased, i.e. deregulated, polyamine accumulation. Overaccumulation of agmatine in the transgenic plants did not affect morphological development.

Download Full-text

Transcriptome Changes Reveal the Molecular Mechanisms of Humic Acid-Induced Salt Stress Tolerance in Arabidopsis

Molecules ◽

10.3390/molecules26040782 ◽

2021 ◽

Vol 26 (4) ◽

pp. 782

Author(s):

Joon-Yung Cha ◽

Sang-Ho Kang ◽

Myung Geun Ji ◽

Gyeong-Im Shin ◽

Song Yi Jeong ◽

...

Keyword(s):

Salt Stress ◽

Abiotic Stress ◽

Humic Acid ◽

Stress Tolerance ◽

Plant Development ◽

Molecular Mechanisms ◽

Abiotic Stress Tolerance ◽

Principal Component ◽

Salt Stress Tolerance ◽

Genes Encoding

Humic acid (HA) is a principal component of humic substances, which make up the complex organic matter that broadly exists in soil environments. HA promotes plant development as well as stress tolerance, however the precise molecular mechanism for these is little known. Here we conducted transcriptome analysis to elucidate the molecular mechanisms by which HA enhances salt stress tolerance. Gene Ontology Enrichment Analysis pointed to the involvement of diverse abiotic stress-related genes encoding HEAT-SHOCK PROTEINs and redox proteins, which were up-regulated by HA regardless of salt stress. Genes related to biotic stress and secondary metabolic process were mainly down-regulated by HA. In addition, HA up-regulated genes encoding transcription factors (TFs) involved in plant development as well as abiotic stress tolerance, and down-regulated TF genes involved in secondary metabolic processes. Our transcriptome information provided here provides molecular evidences and improves our understanding of how HA confers tolerance to salinity stress in plants.

Download Full-text

Down-Regulation of SlGRAS10 in Tomato Confers Abiotic Stress Tolerance

Genes ◽

10.3390/genes12050623 ◽

2021 ◽

Vol 12 (5) ◽

pp. 623

Author(s):

Sidra Habib ◽

Yee Yee Lwin ◽

Ning Li

Keyword(s):

Salt Stress ◽

Abiotic Stress ◽

Plant Growth ◽

Stress Tolerance ◽

Abiotic Stresses ◽

Abiotic Stress Tolerance ◽

Functional Characterization ◽

Flavonoid Biosynthesis ◽

Ros Scavenging ◽

Down Regulation

Adverse environmental factors like salt stress, drought, and extreme temperatures, cause damage to plant growth, development, and crop yield. GRAS transcription factors (TFs) have numerous functions in biological processes. Some studies have reported that the GRAS protein family plays significant functions in plant growth and development under abiotic stresses. In this study, we demonstrated the functional characterization of a tomato SlGRAS10 gene under abiotic stresses such as salt stress and drought. Down-regulation of SlGRAS10 by RNA interference (RNAi) produced dwarf plants with smaller leaves, internode lengths, and enhanced flavonoid accumulation. We studied the effects of abiotic stresses on RNAi and wild-type (WT) plants. Moreover, SlGRAS10-RNAi plants were more tolerant to abiotic stresses (salt, drought, and Abscisic acid) than the WT plants. Down-regulation of SlGRAS10 significantly enhanced the expressions of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) to reduce the effects of reactive oxygen species (ROS) such as O2− and H2O2. Malondialdehyde (MDA) and proline contents were remarkably high in SlGRAS10-RNAi plants. Furthermore, the expression levels of chlorophyll biosynthesis, flavonoid biosynthesis, and stress-related genes were also enhanced under abiotic stress conditions. Collectively, our conclusions emphasized the significant function of SlGRAS10 as a stress tolerate transcription factor in a certain variety of abiotic stress tolerance by enhancing osmotic potential, flavonoid biosynthesis, and ROS scavenging system in the tomato plant.

Download Full-text