Germinating Maize Seeds Research Articles

Investigations on influence of some species of soil fungi on the germination of maize seeds and growth of the seedlings under conditions of the cold test

Investigations on influence of some species of soil fungi on the germination of maize seeds and growth of the seedlings under conditions of the cold test

Sulfite Oxidase is Essential for Timely Germination of Maize Seeds upon Sulfite Exposure

Acid rain adversely affects maize seed germination by sulfite toxicity. Unfortunately, the molecular mechanisms underlying seed germination inhibition by sulfite in maize are largely unknown. Previously, the involvement of sulfite oxidase (SO) in sulfite detoxification in model plants was characterized. Here, we characterized Zea mays SO (ZmSO) in transgenic maize to investigate its role during seed germination upon sulfite exposure. ZmSO was responsive to sulfite stress at the transcriptional level during germination of maize seeds. Unlike the null mutant atso-1, ZmSO-overexpressing transgenic Arabidopsis plants were tolerant to SO2 stress and could effectively rescue the susceptible phenotype of atso-1. Silencing of ZmSO could lead to seed germination delay upon sulfite exposure, but not under normal conditions; interestingly, expressions of several seed germination-related genes encoding hydrolytic enzymes such as α-amylase, β-amylase, and glucosidase were reduced markedly in germinating seeds of ZmSO-compromised lines. This indicates that embryonic SO might alleviate the inhibitory effect of toxic sulfite by sulfite oxidation and the modulation of several hydrolytic enzymes during seed germination. Collectively, these data demonstrate that embryonic SO could be essential for timely seed germination upon sulfite exposure in maize. ZmSO might be a promising target for genetic improvement of crops tolerant to acid rain in molecular breeding programs.

A systematic proteomic analysis of NaCl-stressed germinating maize seeds

Salt (NaCl) is a common physiological stressor of plants. To better understand how germinating seeds respond to salt stress, we examined the changes that occurred in the proteome of maize seeds during NaCl-treated germination. Phenotypically, salt concentrations less than 0.2M appear to delay germination, while higher concentrations disrupt development completely, leading to seed death. The identities of 96 proteins with expression levels altered by NaCl-incubation were established using 2-DE-MALDI-TOF-MS and 2-DE-MALDI-TOF-MS/MS. Of these 96 proteins, 79 were altered greater than twofold when incubated with a 0.2M salt solution, while 51 were altered when incubated with a 0.1M salt solution. According to their functional annotations in the Swiss-Prot protein-sequence databases, these proteins are mainly involved in seed storage, energy metabolism, stress response, and protein metabolism. Notably, the expression of proteins that respond to abscisic acid signals increased in response to salt stress. The results of this study provide important clues as to how NaCl stresses the physiology of germinating maize seeds.

Expression and properties of the mitochondrial and cytosolic forms of fumarase in germinating maize seeds

Fumarase (EC 4.2.1.2) catalyzes reversible interconversion of malate and fumarate. It is usually associated with the tricarboxylic acid cycle in mitochondria, although the cytosolic form has also been detected. We investigated the expression of two fumarase genes and activities of the mitochondrial and cytosolic isoforms of fumarase in maize (Zea mays) scutellum during germination. Both isoforms were purified to electrophoretic homogeneity. The cytosolic form had low optimum pH (6.5) and high affinity to malate (Km 5 μM) when compared with the mitochondrial form (optimum pH 7.0, Km 50 μM). The cytosolic form was strongly activated by Mg(2+) and even more by Mn(2+) , whereas the mitochondrial form was moderately activated by Mg(2+) and Mn(2+) was less effective. The highest fumarase activity in scutellum and a high expression of the gene encoding the cytosolic form were observed during the maximal activity of the glyoxylate cycle. In leaves, the localization of fumarase is only mitochondrial and only one fumarase gene is expressed. It is concluded that the function of cytosolic fumarase in maize scutellum can be related to metabolism of succinate formed in the glyoxylate cycle.

The effects of patulin from Penicillium vulpinum on seedling growth, root tip ultrastructure and glutathione content of maize

A culture of Penicillium vulpinum CM1 isolated from a soil sample cultivated with maize was examined for the production of the mycotoxins cyclopiazonic acid, griseofulvin, patulin (PAT), and roquefortine C. The fungal strain was positive for PAT- and roquefortine C–producing ability, while it showed negative producing ability for cyclopiazonic acid, and griseofulvin. Both PAT and roquefortine C toxins were tested for their inhibitory effect on the germination of maize seeds. Roquefortine C showed no phytotoxicity up to a concentration of 100 μg ml−1. However, a notable reduction in the average values of fresh weight and length of roots and shoots was observed following application of PAT and a culture filtrate of P. vulpinum to maize seedlings. The phytotoxic effect was found to be dose-dependent. To analyse the cellular effects of PAT, maize root tips were treated with PAT at different concentrations. The higher dose of 25 μg ml−1 exhibited morphological changes in the nature of cytoplasm and cytoplasmic organelles as was shown by transmission electron microscopy. Furthermore, an increase in the vacuolation with localized tonoplast dissolution was observed. At this concentration, there was evidence of a disruption of lipid metabolism. On the metabolic level, the phytotoxicity of PAT and the culture filtrate of P. vulpinum led to alterations in the total reduced glutathione (GSH) concentration in maize seedlings. The GSH concentrations examined in roots and shoots after PAT, fungal filtrate or fungal crude extract treatments were enhanced compared with control treatments. Findings further showed higher total GSH levels in shoots than in roots following treatments either with PAT or the fungal crude extract. The results are discussed in the context of known herbicide and metal effects on GSH synthesis and transport mechanisms.

Infecção por Fusarium graminearum e Fusarium verticillioides em sementes de milho

O prévio conhecimento do processo de infecção e do comportamento de patógenos, na avaliação do potencial fisiológico de sementes de milho, é essencial para a tomada de decisão sobre o destino de lotes que podem comprometer a semeadura. Objetivou-se, com este trabalho, determinar o período mínimo necessário para a contaminação de sementes de milho por Fusarium graminearum Schwabe e Fusarium verticillioides (Sacc.) Nirenberg, bem como avaliar a influência destes patógenos na germinação e no vigor de sementes, por meio do teste de frio. Foram utilizadas sementes de três híbridos de milho, as quais entraram em contato com os patógenos em diferentes períodos, avaliados com e sem desinfestação superficial. Após a determinação do período adequado, novas amostras foram contaminadas por F. graminearum e F. verticillioides, sob diferentes níveis de infecção, e submetidas ao teste de germinação em areia. O teste de frio foi realizado com sementes sadias e contaminadas, em diferentes períodos, em câmara fria. O período de 16 horas de contato das sementes de milho com F. graminearum e F. verticillioides foi suficiente para a ocorrência de infecção. F. graminearum e F. verticillioides não interferiram na germinação de sementes de milho, contudo, F. graminearum reduziu o desempenho dos lotes de sementes.

FOLICIST®, A BIOSTIMULANT BASED ON ACETYL-THIOPROLINE, FOLIC ACID AND PLANT EXTRACTS, IMPROVES SEED GERMINATION AND RADICLE EXTENSION

In many agricultural crops, rapid seed germination and seedling growth are required to achieve optimal yields. Seed priming (pre‐sowing seed treatment) is a common practice to improve seed germination especially under unfavorable conditions. FOLICIST® is a biostimulant produced by Biolchim SpA containing plant extracts, acetyl-thioproline, folic acid, and glycine betaine. In tomato, melon, and cherry, FOLICIST® application enhanced plant metabolism leading to improved flowering and fruit set. In some graminaceous and leguminous species, seed treatment with FOLICIST® also enhanced the percentage of germinated seeds and stimulated seedling growth. In the present paper, FOLICIST® was shown to improve seed germination and radicle extension of wheat and maize seeds.

Effect of Different Plant Growth Promoting Rhizobacteria on Maize Seed Germination and Seedling Development

Our study aimed at assessing the effects of 3 Plants Growth Promoting Rhizobacteria (PGPR) either singly or in combination on maize growth under laboratory and greenhouse conditions. Seeds were inoculated with single and combined solution of 108 CFU/ml of Rhizobacteria. Seeds were not inoculated for the control variant. The highest germination percentage was obtained with the combination of Pseudomonas fluorescens and Pseudomonas putida. This combination also recorded the best vigor index, plants circumferences number of leaves and the leaf area. The maximal heights of plants were observed with seeds treated with Azospirillum lipoferum with an increase of 37.32%. The highest rates of underground dry matter were recorded with A. lipoferum, with an increase of more than 56% comparative to control, while the combination P. fluorescens and P. putida increased the aerial dry matter of 59.11%. Finally, the highest value of the aerial biomass was obtained with the plants treated with the combination of P. fluorescens and P. putida and the highest underground biomass was obtained with plants treated only with A. lipoferum. These results suggest that specific combinations of PGPR can be considered as efficient alternative biofertilizers to promote maize seed germination, biomass and crop yield.

Salicylic acid analogues with biological activity may induce chilling tolerance of maize (Zea mays) seeds

One kind of biologically active salicylic acid (SA) analogue (acetylsalicylic acid, ASA) and two inactive compounds (4-aminosalicylic acid and 4-aminobenzoic acid), along with SA were chosen to evaluate their role in inducing chilling tolerance of two different chilling-tolerant maize ( Zea mays L.) inbred lines. These compounds were applied as seed treatments or as a hydroponic application. The results showed that four compounds had no significant effect on germination of maize seeds; however, SA or ASA soaking treatments significantly increased the root length, shoot height, and shoot and root dry weights of seedlings grown under chilling stress. Hydroponic applications of SA or ASA significantly alleviated the accumulation of malondialdehyde, hydrogen peroxide, and superoxide radicals in roots and leaves of both lines under chilling stress, and the applications also increased the photosynthetic pigments, including chlorophyll a, chlorophyll b, and carotenoids. However, 4-aminosalicylic acid and 4-aminobenzoic acid applications had no significant effect in ameliorating the growth inhibition of seedlings under chilling stress. This study showed that SA and ASA significantly induced the chilling tolerance of maize; however, 4-aminosalicylic acid and 4-aminobenzoic acid were not effective in inducing tolerance to chilling stress. The results suggest that only SA analogues with biological activity may have the ability to induce chilling tolerance of maize.

MicroRNA Transcriptomic Analysis of Heterosis during Maize Seed Germination

Heterosis has been utilized widely in the breeding of maize and other crops, and plays an important role in increasing yield, improving quality and enhancing stresses resistance, but the molecular mechanism responsible for heterosis is far from clear. To illustrate whether miRNA-dependent gene regulation is responsible for heterosis during maize germination, a deep-sequencing technique was applied to germinating embryos of a maize hybrid, Yuyu22, which is cultivated widely in China and its parental inbred lines, Yu87-1 and Zong3. The target genes of several miRNAs showing significant expression in the hybrid and parental lines were predicted and tested using real-time PCR. A total of 107 conserved maize miRNAs were co-detected in the hybrid and parental lines. Most of these miRNAs were expressed non-additively in the hybrid compared to its parental lines. These results indicated that miRNAs might participate in heterosis during maize germination and exert an influence via the decay of their target genes. Novel miRNAs were predicted follow a rigorous criterion and only the miRNAs detected in all three samples were treated as a novel maize miRNA. In total, 34 miRNAs belonged to 20 miRNA families were predicted in germinating maize seeds. Global repression of miRNAs in the hybrid, which might result in enhanced gene expression, might be one reason why the hybrid showed higher embryo germination vigor compared to its parental lines.

Ecotoxicological risks associated with tannery effluent wastewater

The problem of water pollution acquires greater relevance in the context of a developing agrarian economy like Pakistan. Even though, the leather industry is a leading economic sector in Pakistan, there is an increasing environmental concern regarding tanneries because they produce large amounts of potentially toxic wastewater containing both trivalent and hexavalent chromium, which are equally hazardous for human population, aquaculture and agricultural activities in the area. Therefore, we defined the scope of the present study as to employ different bioassays to determine the eco-toxic potential of tannery effluent wastewater (TW) and its chromium based components, i.e., potassium dichromate (K2Cr2O7) and chromium sulfate Cr2(SO4)3. Particle-induced X-ray emission (PIXE) analysis of TW was carried out to determine the concentration of chromium in TW and then equal concentrations of hexavalent (K2Cr2O7) and trivalent chromium Cr2(SO4)3 were obtained for this study. Cytotoxicity assay, artemia bioassay and phytotoxicity assay was utilized to investigate the eco-toxicological potential of different concentrations of TW, K2Cr2O7 and Cr2(SO4)3. All the dilutions of TW, K2Cr2O7 and Cr2(SO4)3 presented concentration dependent cytotoxic effects in these assays. The data clearly represents that among all three tested materials, different dilutions of K2Cr2O7 caused significantly more damage (P<0.001) to vero cell, brine shrimp and germination of maize seeds. Interestingly, the overall toxicity effects of TW treated groups were subsequent to K2Cr2O7 treated group. Based on biological evidences presented in this article, it is concluded that hexavalent chromium (K2Cr2O7) and TW has got significant eco-damaging potential clearly elaborating that environmental burden in district Kasur is numerous and high levels of chromium is posing a considerable risk to the human population, aquaculture and agricultural industry that can obliterate ecosystem surrounding the tanneries.

Effect of Brevibacterium iodinum RS16 and Methylobacterium oryzae CBMB20 Inoculation on Seed Germination and Early Growth of Maize and Sorghum-sudangrass hybrid Seedling under Different Salinity Levels

Salinity is one of the most relevant abiotic factor limiting crop yield and its net primary productivity. In addition, salinity induces an increased stress ethylene synthesis in plants which, in turn, exacerbate the responses to the stressor. Bacterial single or co-inoculation effect was tested using previously characterized plant growth promoting (PGP) bacteria Brevibacterium iodinum RS16 and Methylobacterium oryzae CBMB20 on maize and sorghum-sudan grass hybrid under different concentrations of NaCl. Non-inoculated maize and sorghum-sudangrass hybrid showed 33.4% and 20.0% reduction in seed germination under highest NaCl (150 mM) level tested. However, under the same NaCl concentration, co-inoculation with B. iodinum RS16 and M. oryzae CBMB20 PGP strains increased the seed germination in maize (16.7%) and sorghum-sudangrass hybrid (4.4%). In Gnotobiotic growth pouch experiments conducted for maize and sorghum-sudangrass hybrid, co-inoculation of PGP B. iodinum RS16 and M. oryzae CBMB20 mitigated the salinity stress and promoted root length by 22.9% and 29.7%, respectively. Thus the results of this study could help in development of potential bioinoculants that may be suitable for crop production under saline conditions.

Some Characteristics of a Plant Growth Promoting &amp;lt;i&amp;gt;Enterobacter&amp;lt;/i&amp;gt; sp. Isolated from the Roots of Maize

Some properties of an Enterobacter sp. isolated from the roots of maize are described. Isolation was carried out using the semisolid enrichment culture technique and subsequent plating, both on nitrogen free biotin medium. Morphological, biochemical and phylogenetic characterization using the MicroSeqTM 16S rDNA technique were employed in identification of isolate, which was revealed to be closest matched at 99.4% with Enterobacter asburiae. The isolate possessed properties of plant growth promoting bacteria. Thus, it produced indole-3-acetic, plant polymer hydrolyzing enzymes, pectinase and cellulase as well as ammonia in vitro. The isolate grew well in the presence of both 3% NaCl and 10 μg of streptomycin. In plate bioassays, isolate promoted the germination of both maize and rice seeds as well as root and lateral root growth resulting in weight increases of seedlings over their controls. Experiments to quantify ability of isolate to promote plant growth was performed using hydroponics solutions and as appropriate, an inoculum of the isolate. Pot experiments were also employed. Results from these studies showed that isolate enhanced nitrogen accumulation and significantly (p < 0.05), improved the growth of maze seedlings over controls. Isolate has potential for utilizetion as inocula for sustainable production of cereals.

Exogenous mammalian sex hormones mitigate inhibition in growth by enhancing antioxidant activity and synthesis reactions in germinating maize seeds under salt stress

Mammalian sex hormones (MSH)-progesterone, β-estradiol and androsterone-enhance plant growth and development by stimulating significant morphological and biochemical parameters under normal conditions. However, there is no report regarding their effects on plants exposed to environmental stress conditions. Therefore, the present study was focused on elucidating the possible positive effects of MSH on seedling growth, antioxidant activity and synthesis reactions in maize seeds exposed to salt stress, one of the most important environmental stresses. For this purpose, the various concentrations (10⁻⁶, 10⁻⁸, 10⁻¹⁰ and 10⁻¹² mol L⁻¹) of MSH were studied. Salinity (100 mmol L⁻¹ NaCl) significantly reduced root length and seedling height, whereas MSH treatment significantly ameliorated the adverse effects of salinity on root length and seedling height. On the other hand, although salinity increased soluble protein, soluble sugar and proline content in 7-day-old maize seedlings, these were higher in MSH-treated seedlings. Similarly, MSH treatment augmented superoxide dismutase, peroxidase and catalase activities under salt stress, whereas it decreased superoxide production and lipid peroxidation level. The most favorable concentrations were determined as 10⁻⁸ mol L⁻¹ for progesterone and β-estradiol and 10⁻¹⁰ mol L⁻¹ for androsterone. Exogenous MSH application was found to have an important ameliorative effect on growth of seeds exposed to salt stress by stimulating antioxidant activity and synthesis reactions. This is the first study investigating the effects of MSH on germination of seeds exposed to stress conditions.

ABA treatment of germinating maize seeds induces VP1 gene expression and selective promoter‐associated histone acetylation

Seed germination commences from a low metabolic state to a bioactive state and is associated with changes in the pattern of gene expression. Recent studies have revealed that epigenetic processes are involved in abscisic acid (ABA)-regulated seed germination processes. In this study, we showed that the expression of both histone acetyltransferases (HATs) and histone deacetylases (HDACs) was increased gradually during seed germination accompanying an increase in overall acetylation level of histone H3. Application of exogenous ABA repressed the expression of HATs as well as HDACs and delayed histone acetylation. Suppressing HDAC by treatment with an HDAC inhibitor, trichostatin A (TSA), led to an increase in global histone acetylation and inhibited seed germination and growth. However, ABA and TSA both delayed the downregulation of the embryogenesis-related gene viviparous1 (VP1) during seed germination. The further chromatin immunoprecipitation experiments showed that the promoter region of the VP1 gene was deacetylated during seed germination, and this deacetylation event was inhibited by both ABA and TSA. These results suggested that a balance of the two enzymes HATs and HDACs affected the acetylation status of the VP1 gene and ABA selectively activated its transcription by an accumulation of acetylated histone H3 associated with the promoter region during seed germination.

Protein composition analysis of oil bodies from maize embryos during germination

Seed oil bodies (OBs) are intracellular particles that store lipids. In maize embryos, the oil bodies are accumulated mainly in the scutellum. Oil bodies were purified from the scutellum of germinating maize seeds and the associated proteins were extracted and subjected to 2-DE analysis followed by LC–MS/MS for protein identification. In addition to the previously known oil body proteins oleosin, caleosin and steroleosin, new proteins were identified.

Role of differential expression of sdh1-1 and sdh1-2 genes in alteration of isoenzyme composition of succinate dehydrogenase in germinating maize seeds

A probable mechanism of alteration of the isoenzyme composition of succinate dehydrogenase (SDH) due to differential expression of genes encoding subunit A was considered. The alteration of SDH activity during maize seed germination was investigated, and its maximal activity on day 4-5 of germination was found. The alteration of the sdh1-1 and sdh1-2 gene expression level during maize seed germination was evaluated using the quantitative polymerase chain reaction method. The presence of four forms of the studied enzymes, providing multiple SDH functions was found in maize inflorescence using electrophoresis in polyacrylamide gel.

Seed Vigor of Maize Grown on the Contaminated Soils by Cadmium

Cadmium is one of the highly toxic heavy metals in the agricultural soils. The effects of cadmium on plant growth have been reported by many authors, but the effects of cadmium content of seeds on germination and seed vigor have not been reported in the literature. A cold test study was conducted to evaluate the effects of different levels of cadmium contamination of soils on seed vigor of maize grown on contaminated soils. The experiment was designed in a randomized complete block design with a split-plot arrangement. Soil series (Comba and Reyhanli) were in the main plots and cadmium contamination levels (0, 10, 20, 40 and 60 mg kg-1) were in the sub-plots. Four replications of 50 seeds from each treatments were planted in cold test for germination and seed vigor. Germination and strong seedling ratios of maize seeds significantly decreased with increases in cadmium contents of soils and the highest germination and strong seedling ratios (90.3, 84.3%, respectively) were observed at uncontaminated soils, whereas, the lowest ratios (79.8, 70.8%, respectively) were at the highest level of Cd contaminated soils

The effect of biochars on maize (Zea mays) germination

Biochar made from biosolids, corn stover, eucalyptus, fresh pine or willow pyrolysed at 550°C and incorporated into Manawatu fine sandy loam or Waitarere sand at rates from 0 to 10 t/ha did not significantly affect the germination or early growth (root and coleoptile length, and dry weight) of maize seeds. There were no interactions between type or rate of biochar with soil type. The results suggest that biochar incorporation prior to a maize crop should be investigated as a method of increasing stable soil carbon with the potential for mitigating carbon emissions.

Indole-3-acetic acid production by Streptomyces sp. isolated from some Thai medicinal plant rhizosphere soils

A collection of Streptomyces spp. isolated from the rhizosphere soils of 14 Thai medicinal plants were found to produce, the plant growth hormone indole-3-acetic acid (IAA) in a yeast malt extract medium supplemented with 2 mg/mL L-tryptophan. Streptomyces CMU-H009 recovered from soil associated with lemongrass (Cymbopogon citratus) was very effective in producing IAA. Based on the 16S rDNA sequence analysis, this strain was most closely related to Streptomyces viridis NBRC 13373T (99.3% similarity). The IAA production was maximums (300 mg/mL) when the strain CMU-H009 was cultivated in a yeast malt extract broth amended with 2 mg/mL L-tryptophan a pH 7.0, and incubated at 30 o C with shaking at 125 rpm for 3 d. The culture filtrate from the strain CMU-H009 stimulated a significant increase in the germination and root elongation of maize (Zea mays) and cow pea (Bruguiera parviflora) seeds. The IAA from this strain was extracted, purified and identified by thin layer chromatography.