Seed Vigor Parameters Research Articles

Bacillus subtilis bacteriocin Bac 14B with a broad inhibitory spectrum: Purification, amino acid sequence analysis, and physicochemical characterization

Bacillus subtilis strain 14B was used to produce a novel antimicrobial peptide (bacteriocin) called Bac 14B. Pure bacteriocin was obtained after heat and acidic treatments (80°C and pH 4), precipitation by ammonium sulfate, and chromatography on Sephadex G-50 and Mono Q Sepharose columns. Based on MALDI-TOF mass spectrometry analysis, purified Bac 14B is a monomer protein with a molecular mass of 20110.13 Da. N-terminal sequencing allowed for the straightforward identification of its first 12 residues, which were of a pure bacteriocin. It also revealed that this bacteriocin contained a unique sequence, namely M-L-K-A-N-L-Q-N-P-L-N-A, suggesting the identification of a novel compound. Bac 14B was stable for 1 h at temperatures up to 80°C and pH of 4 ∼ 8. It also proved sensitive to various proteases, which demonstrated its protein nature. Bac 14B displayed a bacteriolytical mode of action and a broad range of inhibitory spectra toward Gram-positive and -negative pathogens. Interestingly, based on conventional agronomic seed vigor parameters, the application of Bac 14B (500 activity units/mL) to various crops revealed that this bacteriocin was a potent exogenous enhancer of growth that stimulated the seedling vigor of tomatoes and muskmelons. Compared to those of the control, the germination percentage, shoot weight, shoot height, and root length were all significantly enhanced in Bac 14B-treated plant seeds. Bac 14B also exhibited effective disinfectant properties against a wide range of seedborne diseases and significant effects on the control of damping off diseases, particularly at the pregermination stage. It also proved to be effective against root rot diseases caused by Alternaria solani and other bacterial seedborne pathogens such as wilt diseases. The findings indicate that Bac 14B is the first B. subtilis-produced bacteriocin ever reported to exhibit such promising biological properties.

Effect of hydroxytyrosol-rich preparations on phenolic-linked antioxidant activity of seeds

Hydroxytyrosol-rich extract (HRE) and hydroxytyrosol-rich olive mill wastewater (HROMW) were used as exogenous growth enhancers to stimulate tomato seedling vigor. The tomato seeds soaking in 10% w/v HROMW or HRE solutions were optimum in maximally enhancing seedling performance according to biochemical seed vigor parameters. Biochemical parameters as the average glucose-6-phosphate dehydrogenase (G6PDH) activity in HRE-treated seeds (915.11 nmoles min−1 mg−1 protein) was higher than control (629.58 nmoles min−1 mg−1 protein) and correlated with the increased phenolic content (3530 μg g−1 fw) and 1,1-diphenyl-2-picrylhydrazyl (DPPH)-based antioxidant activity (70.60%), respectively. Some key enzymes, guaiacol peroxidase (GPX) (6100.65 nmoles min−1 mg−1 protein) and catalase (2.04 μmoles min−1 mg−1 protein), were also higher in response to treatments and correlated with enhanced phenolic content and antioxidant activity. This study supports the hypothesis that the exogenous phenolic application stimulates the pentose phosphate pathway through an over-expression of endogenous phenolic synthesis and an increase in free-radical scavenging antioxidant activity. Therefore, the current study indicates the enhancement of seed vigor by HRE especially and HROMW as reflected by the stimulation of biochemical responses.

Correlation and Path Coefficient Analyses of Laboratory Tests as Predictors of Field Emergence in Lentil (Lens culinarisMedikus)

ABSTRACT Field establishment in Lentil is a key determinant in its production. To investigate the prediction of field emergence through various laboratory parameters, correlation studies between seed vigor tests and field emergence were carried out across two consecutive years in Sudan and in Syria. Correlation and path coefficient analyses were done to find the association of these seed vigor parameters and assess the direct and indirect contributions of each parameter towards field emergence. Correlations of speed of germination, seedling dry weight and electrical conductivity with field emergence in two types of soil were significant in Sudan. In Syria, no significant correlation was observed between vigor tests and field emergence. In Sudan, path analyses showed that seedling dry weight and 100-seed weight consistently reflected the highest positive direct contribution towards field emergence in the two types of soil whereas the highest negative direct effect was shown by seedling growth rate, followe...

Seed vigour studies in corn, soybean and tomato in response to fish protein hydrolysates and consequences on phenolic-linked responses

Seed priming with fish protein hydrolysates (FPH) has been studied for the enhancement of seed vigour of corn, soybean and tomato. The influence of FPH at 2.5 mL/L and 5.0 mL/L on traditional agronomic parameters for seed vigour (germination percentage, seedling weight, seedling height) and potential new vigour-associated parameters (phenolic content, antioxidant activity, guaiacol peroxidase (GuPX) activity, chlorophyll content) was investigated. FPH treatment preferentially stimulated seedling vigour in the following order: soybean > tomato > corn. For soybean, FPH at 2.5 mL/L and 5 mL/L improved the majority of the seed vigour parameters (seedling weight and height, phenolic content, antioxidant activity and chlorophyll content, and lignification-associated GuPX activity). Similarly, for tomato, FPH at 2.5 mL/L stimulated seedling weight and height, GuPX activity and chlorophyll content. However, FPH did not stimulate corn seed vigour. Our results suggest an ability of proline precursor-rich FPH to improve of plant growth and development (e.g., seed vigour) in phenolic-rich plant species through modulation of phenolic and chlorophyll metabolisms.

Effect of vitamin C and folic acid on seed vigour response and phenolic-linked antioxidant activity

Folic acid and vitamin C were used in the concentration range of 0–500 μM as exogenous growth enhancers to stimulate pea ( Pisum sativum) seedling vigour. The results suggest that a concentration of 50 μM folic acid and 500 μM vitamin C were optimum in maximally enhancing seed vigour and potentially seedling performance according to both agronomic and biochemical seed vigour parameters. Results indicated that germination percentage, shoot weight, shoot height, and root length were enhanced in folic acid and vitamin C treated plants compared to control plants. The levels of enhanced phenolic content in response to folic acid and vitamin C treatments were highest on days 8 and 10. Evaluation of critical biochemical parameters indicated that the average glucose-6-phosphate dehydrogenase (G6PDH) activity and proline content in response to treatments were higher than control and correlated to enhanced phenolic content and DPPH-based antioxidant activity. Key enzymes, guaiacol peroxidase (GPX), superoxide dismutase (SOD), and catalase (CAT) were also higher in response to treatments and correlated to enhanced phenolic content and DPPH-based antioxidant activity. Taken together, these studies support the hypothesis that the proline-linked pentose phosphate pathway stimulates phenolic synthesis and related free-radical scavenging antioxidant activity. Further, this proline-linked pentose phosphate pathway stimulation in response to folic acid and vitamin C was also correlated to antioxidant enzyme response indicated by the stimulation of GPX, SOD, and CAT activities. Therefore, this study indicates the enhancement of seed vigour response by folic acid and vitamin C as reflected in both agronomic and biochemical responses, and this occurred through the stimulation of phenolic-linked antioxidant response that is likely positively modulated through the proline-linked pentose phosphate pathway.

Correlation of Field Emergence Rate and Seed Vigor Criteria in Barley Cultivars1

Thirteen seed vigor parameters were compared in two 2‐row and four 6‐row barley (Hordeum vulgare L.) cultivars to determine selection criteria for predicting rate of field emergence. The materials also represented four spring and two winter types. Seed weight, 3‐day seedling adenosine triphosphate (ATP) content, 3‐day seedling total adenosine phosphates (TAP), 5‐day endosperm α‐amylase activity, 3‐day endosperm c~‐amylase activity, 4‐hour hydrated embryo TAP, 4‐day hydrated embryo ATP content, 7‐day seedling dry weight, 3‐day seedling dry weight, and 3‐day seedling shoot length were all significantly correlated (P≤0.01) with field emergence rate but in decreasing order, respectively. Based on the results of stepwise multiple regression analysis, it appeared that seed weight, 3‐day seedling ATP content, TAP content of hydrated embryo, and 7‐day seedling dry weight would be good seed vigor indices for predicting field emergence rate.