1,721,044 research outputs found
Methylgyoxal signalling in Phaseolus vulgaris under phosphate deficiency
Full text linkMasters of ScienceIn this study, we observed that phosphate (P) deficiency stunted plant growth and produced plants with poor morphological characteristics (yellow and small leaves). Furthermore, we treated plants with 0.8 mM (control) and 0.02 mM P (deficient) in addition to 6 μM methylglyoxal (MG) and we observed that the plants treated with MG had a higher germination, and better morphological characteristics (the leaves were more dark green and bigger in size) compared to the P deficient plants. However, we also observed that the P deficient plants treated with MG had low levels of both O2- and H2O2 and this could be a possible reason for the improved growth and morphological characteristics. In contrast, the P deficient plants not treated with MG had high levels of O2- and H2O2 which could be the possible reason for the observed cell death. We also performed biochemical assays including superoxide dismutase, ascorbate peroxidase, malondialdehyde content, ascorbic acid content, catalase, and most of the assays showed high levels of reactive oxygen species (ROS) and low levels of antioxidant activities in plants not treated with MG while high levels of antioxidant activities and low levels of ROS were observed in plants treated with exogenous MG. Since nitric oxide (NO) is also known to be a signalling molecule, we did a NO assay and observed that NO content increased under low exogenous doses of MG. From our findings we came to a hypothesis that MG modulates P deficiency stress in P. vulgaris through NO signalling or it might be that NO and MG work in tandem to modulate signalling pathways under P deficiency. Finally, we looked at the nutrient profile and the results showed that while there was a poor nutrient profile generally under P deficiency, there was an improvement in nutrient profile when MG was administered at low doses
Impact of vanadium stress on physiological and biochemical characteristics in heavy metal susceptible and tolerant Brassicaceae
No full text>Magister Scientiae - MScThere is an influx in heavy metals into soils and ground water due to activities
such as increased mineral mining, improper watering and the use of heavy metal
contaminated fertilizers. These heavy metals are able to increase the ROS species
within plants which may result in plant metabolism deterioration and tissue
damage. Heavy metals may also directly damage plants by rendering important
enzymes non-functional through binding in metal binding sites of enzymes. The
heavy metal focused on in this study was vanadium due to South Africa being
one of the primary produces of this metal. Two related Brassica napus L cultivars
namely Agamax and Garnet which are economically and environmentally
important to South Africa were exposed to vanadium. Physiological experiments
such as cell death, chlorophyll and biomass determination were conducted to
understand how these cultivars were affected by vanadium toxicity. A low cost,
sensitive and robust vanadium assay was developed to estimate the amount of
vanadium in samples such as water, soils and plant material. The oxidative state
as well as the antioxidant profile of the two cultivars were also observed under
vanadium stress. A chlorophyll assay which was conducted on the two cultivars exposed to vanadium showed a marked decrease in chlorophyll A in the
suspected sensitive cultivar which was Garnet. However, the suspected tolerant
cultivar Agamax fared better and the decrease in chlorophyll A was much less. A
similar trend was observed for the two cultivars when the cell death assay was
conducted. The vanadium assay showed that Garnet had higher concentrations
of vanadium within its leaves and lower concentrations in its roots when
compared to Agamax. This observation displayed that Agamax had inherent
mechanisms which it used to localize vanadium in its roots and which assisted in
its tolerance to the vanadium stress.
The oxidative state was determined by doing assays for the specific reactive
oxygen species namely hydrogen peroxide and superoxide. It was observed that
vanadium treated Garnet leaves had higher reactive oxygen species (ROS)
production when compared to the Agamax treated leaves. In-gel native PAGE
activity gels were conducted to determine the antioxidant profile for the two
cultivars which were exposed to vanadium. The antioxidant enzymes which were
under investigation were ascorbate peroxide (APX), superoxide dismutase (SOD)
and glutathione-dependent peroxidases (GPX-like) as these enzymes are known
to be responsible for controlling the ROS produced in the plants. The GPX-like
profile consisted of three isoforms. No isoforms were inhibited by vanadium
treatments but one isoform had increased activity in both the Garnet and
Agamax treated samples. The SOD profile for Garnet consisted of six isoforms and Agamax had seven isoforms. One isoform which was visualized in both
Agamax as well as Garnet was inhibited by vanadium treatments. Agamax also
had two isoforms which were up-regulated however the corresponding isoforms
in Garnet showed no change. The Ascorbate peroxidase profile consisted of
seven isoforms for both Garnet and Agamax. No isoforms were inhibited by
vanadium treatment. Three isoforms were up-regulated in Garnet and Agamax
under vanadium treatments.
Here, it is illustrated that Garnet lacked certain mechanisms found in Agamax
(and thus experienced more cell death, yield and chlorophyll loss) and performed
worst under high vanadium concentrations. Although Garnet increased the
activity of some of its antioxidant isoforms in response to increasing ROS levels it
was not adequate to maintain a normal oxidative homeostasis. This disruption in
oxidative homeostasis lead to plant damage. Agamax was observed to produce
less ROS than Garnet and was able to control the ROS produced more effectively
than Garnet and thus less damage was observed in Agamax
Methylgyoxal signalling in Phaseolus vulgaris under phosphate deficiency
No full textMasters of ScienceIn this study, we observed that phosphate (P) deficiency stunted plant growth and produced plants with poor morphological characteristics (yellow and small leaves). Furthermore, we treated plants with 0.8 mM (control) and 0.02 mM P (deficient) in addition to 6 μM methylglyoxal (MG) and we observed that the plants treated with MG had a higher germination, and better morphological characteristics (the leaves were more dark green and bigger in size) compared to the P deficient plants. However, we also observed that the P deficient plants treated with MG had low levels of both O2- and H2O2 and this could be a possible reason for the improved growth and morphological characteristics. In contrast, the P deficient plants not treated with MG had high levels of O2- and H2O2 which could be the possible reason for the observed cell death. We also performed biochemical assays including superoxide dismutase, ascorbate peroxidase, malondialdehyde content, ascorbic acid content, catalase, and most of the assays showed high levels of reactive oxygen species (ROS) and low levels of antioxidant activities in plants not treated with MG while high levels of antioxidant activities and low levels of ROS were observed in plants treated with exogenous MG. Since nitric oxide (NO) is also known to be a signalling molecule, we did a NO assay and observed that NO content increased under low exogenous doses of MG. From our findings we came to a hypothesis that MG modulates P deficiency stress in P. vulgaris through NO signalling or it might be that NO and MG work in tandem to modulate signalling pathways under P deficiency. Finally, we looked at the nutrient profile and the results showed that while there was a poor nutrient profile generally under P deficiency, there was an improvement in nutrient profile when MG was administered at low doses
Isolation and characterisation of leaf endophytic bacteria from weed plants for enhancing salinity stress tolerance in Brassica napus
Full text link>Magister Scientiae - MScIn an ever changing environment, plants are constantly challenged by various abiotic stresses such as salinity, which limits global crop production. This directly affects food availability for the global population, which is projected to increase to 9.5 billion by 2050, which in turn places great pressure on natural resources and food security. These environmental adversities induce the accumulation of reactive oxygen species (ROS) hydrogen peroxide, hydroxyl and superoxide radicals which cause severe oxidative damage to plants. The equilibrium between the production and detoxification of ROS is then dependent on the modulation of enzymatic and non-enzymatic antioxidants to achieve plant homeostasis.202
Isolation and characterization of bacterial endophytes for growth promotion of Phaseolus vulgaris under salinity stress
No full text>Magister Scientiae - MScAs the global human population grows, so does the demand for faster food production rates. Owing to this, agricultural practices have had to expand and move into semi-arid and arid regions, too, where frequent irrigation is essential. However, irrigated ground water contains many salt ions (mainly Na+ and Cl-) which contribute to soil salinization on croplands. Soil salinity negatively impacts crop growth and yield and thus, strategies for the alleviation of salt stress on crop plants have had to be developed. This study assessed the use of plant growth promoting bacteria (PGPB). The aim of this study was to isolate, identify and characterize bacterial endophytes isolated from the halophyte, Arctotheca calendula. Endophytes were identified using 16S rDNA and were screened for plant growth promoting properties including nitrogen fixation, phosphate and zinc solubilization, siderophore, ammonia and indole-3-acetic acid (IAA) when exposed to 0 mM, 300 mM and 600 mM NaCl. The endophytes had been identified as Erwinia persicina NBRC 102418T, Bacillus marisflavi JCM 11544T, Ochrobactrum rhizosphaerae PR17T, Microbacterium gubbeenense DSM 15944T and Bacillus zhangzhouensis DW5-4T and all of which had demonstrated some plant growth promoting characteristics. Thereafter, we aimed to demonstrate plant growth promotion of P. vulgaris cv. Star 2000 inoculated with PGPB under salinity stress. P. vulgaris cv. Star 2000 seeds were inoculated with the PGPB and exposed to 0 mM and 100 mM NaCl. Post-harvest, plants were assessed for their dry mass, cell death, superoxide concentration and nutrient content. It was discovered that salinity negatively impacted P. vulgaris cv. Star 2000’s dry mass, NaCl-induced cell death, and differentially influenced superoxide concentration, nutrient uptake and content of the leaf and root material in the inoculated and control treatments. However, the isolated PGPB had been able to mitigate the negative effects of soil salinity on P. vulgaris cv. Star 2000
Comparative analysis of 3, 3'- diindolylmethane and indole-3-carbinol respective treatments in Brassica napus L.
No full textMagister Scientiae - MSc (Biotechnology)Lately, there has been serious contamination of soils and ground water caused by mineral
mining and environmental pollution leading to heavy metal accumulation within soils and over
time rendering the soil infertile. The contaminated soil affects crop; yield, germination
percentage and leads to seed dormancy. Additionally, as plants are sessile organisms, exposure
to environmental stress involves different defense cycles and signalling molecules. Oxidative
stress, increases the production of reactive oxygen species (ROS) at greater rates than that of
the metabolism. Moreover, oxidative damage leads to the loss in cellular function and
eventually death. Nonetheless, plants have adapted ROS-scavenging systems driven by
reduction-oxidation reactions as defense mechanisms. In this way, cellular homeostasis is an
essential defending process and finding means to optimize these reactions would benefit in the
development of plants. Hence, environmentally friendly solutions are being reported such as
using glucosinolates, a secondary plant metabolite found in relatively high concentrations
within crucifers such as Brassica napus L
Isolation and characterization of plant growth promoting endophytic bacteria from Eriocephalus africanus roots]
No full textMagister Scientiae - MSc (Biotechnology)Endophytic bacteria are known to have an endosymbiotic relationship with plants and
provide them with many beneficial properties. These bacteria stimulate plant hormones,
provide protection from pathogens and increase nutrient availability in the environment.
In this study some of these potential growth factors were tested.
Endophytic bacteria have the potential to be of great value for the increase of crop
production. They offer a variety of processes that aid in plant growth promotion in an ecofriendly
manner. The use of endophytic bacteria provides a cheaper and cleaner approach
compared to industrial made fertilizers. They also have potential uses in bioremediation to
clean the environment polluted by industrial processes.
Endophytes were isolated and showed significant growth improvement. Each isolate
displayed different morphologies. Isolates were tested for classical growth promotion
mechanisms such as the ability to solubilize phosphate, Indole-3-acetic acid and
siderophore production. Inductively Coupled Plasma Optical Emission Spectrometry was
performed to measure the effect of the isolates on the plants nutrient profile.
The isolates were then tested again while the plants were under heavy metal stress to
determine if they were still capable of growth promotion. The plants were then assayed
for cell death using Evans blue and biomass was measured to determine the effect of
vanadium stress. Inductively Coupled Plasma Optical Emission Spectrometry was
performed again to assess the change in nutrient profile while under vanadium stress
Effects of exogenous myristic acid on growth and germination of Brassica napus L. under zirconium toxicity
No full textMagister Scientiae - MSc (Biotechnology)Lipids when exogenously applied are known to cause various changes in ROS
levels produced within plants. They can either be beneficial to the plant when not
stimulating the overproduction of ROS thus resulting in improved germination and
development or on the contrary, increasing the level of ROS produced, causing
oxidative stress and thus leading to cell death of the plant. In this study, we report
that a saturated fatty acid known as MA increased the germination percentages of
Brassica napus L. seedlings when applied at a low concentration. When applied at
higher concentrations, it was shown that elevated levels of ROS within the
seedlings occurred therefore leading to a decrease in germination percentage as
well as stunting of seedling growth. Physiological experiments such as biomass and
cell death determination were conducted to further elucidate the effects of MA on
the seedlings. Biochemical assays were performed to determine the oxidative state
of specific ROS such as superoxide (O2-) and hydrogen peroxide (H2O2)
Effects of exogenous myristic acid on growth and germination of Brassica napus L. under zirconium toxicity
Full text linkMagister Scientiae - MSc (Biotechnology)Lipids when exogenously applied are known to cause various changes in ROS
levels produced within plants. They can either be beneficial to the plant when not
stimulating the overproduction of ROS thus resulting in improved germination and
development or on the contrary, increasing the level of ROS produced, causing
oxidative stress and thus leading to cell death of the plant. In this study, we report
that a saturated fatty acid known as MA increased the germination percentages of
Brassica napus L. seedlings when applied at a low concentration. When applied at
higher concentrations, it was shown that elevated levels of ROS within the
seedlings occurred therefore leading to a decrease in germination percentage as
well as stunting of seedling growth. Physiological experiments such as biomass and
cell death determination were conducted to further elucidate the effects of MA on
the seedlings. Biochemical assays were performed to determine the oxidative state
of specific ROS such as superoxide (O2-) and hydrogen peroxide (H2O2)
Physiological and biochemical characterization, of antimony stress, responses in Phaseolus vulgaris
Full text linkMagister Scientiae - MSc (Biotechnology)The mining industry in South Africa is of immense importance as this sector contributes
largely to the countries income. In the Limpopo province, a large production of antimony
(Sb) is generated per year. Antimony (Sb) is a trace element, which accumulates in the
environment through anthropogenic activities, such as mining and smelting industries.
Antimony is toxic to all living organisms and plants, and it is found to increase the
peroxidation of membrane lipids and encourage an antioxidant response. Sb contamination
in plants also accounts for DNA damage. The reduction in yield is due to the disruption of
plant metabolism by reactive oxygen species (ROS).
To combat abiotic stresses, plants have generated a signalling network that utilises multiple
growth regulators that would offer protection against the stress. An increase in ROS is one
of the responses to abiotic stresses. ROS is generated in response to the pants interaction
with heavy metals, through the Harber-Weiss reaction. ROS compounds include:
superoxide, hydrogen peroxide and hydroxyl radicals. Under normal conditions ROS
molecules are produced as by-products, however, under stressful conditions the production
of ROS molecules are increased to levels where they are detrimental to the plants.
Therefore, the accumulation of ROS results in damage to proteins, lipids, carbohydrates and
DNA which would lead to cellular death. ROS accumulation is thought to be a result of the
disruption in the balance of ROS production and the anti-oxidation systems. The antioxidative
system is thus introduced to restore the balance of ROS molecule production and
to combat oxidative damage caused by the ROS molecules. The anti-oxidative system
consists of various enzymes: superoxide dismutase, catalase, and ascorbate peroxidase and
glutathione reductase. Each antioxidant scavenges one or two ROS molecules
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