Non-aged Seeds Research Articles

Arabidopsis DNA glycosylase MBD4L improves recovery of aged seeds.

DNA glycosylases initiate the base excision repair (BER) pathway by catalyzing the removal of damaged or mismatched bases from DNA. The Arabidopsis DNA glycosylase methyl-CpG-binding domain protein 4 like (MBD4L) is a nuclear enzyme triggering BER in response to the genotoxic agents 5-fluorouracil and 5-bromouracil. To date, the involvement of MBD4L in plant physiological processes has not been analyzed. To address this, we studied the enzyme functions in seeds. We found that imbibition induced the MBD4L gene expression by generating two alternative transcripts, MBD4L.3 and MBD4L.4. Gene activation was stronger in aged than in non-aged seeds. Seeds from mbd4l-1 mutants displayed germination failures when maintained under control or ageing conditions, while 35S:MBD4L.3/mbd4l-1 and 35S:MBD4L.4/mbd4l-1 seeds reversed these phenotypes. Seed nuclear DNA repair, assessed by comet assays, was exacerbated in an MBD4L-dependent manner at 24 h post-imbibition. Under this condition, the BER genes ARP, APE1L, and LIG1 showed higher expression in 35S:MBD4L.3/mbd4l-1 and 35S:MBD4L.4/mbd4l-1 than in mbd4l-1 seeds, suggesting that these components could coordinate with MBD4L to repair damaged DNA bases in seeds. Interestingly, the ATM, ATR, BRCA1, RAD51, and WEE1 genes associated with the DNA damage response (DDR) pathway were activated in mbd4l-1, but not in 35S:MBD4L.3/mbd4l-1 or 35S:MBD4L.4/mbd4l-1 seeds. These results indicate that MBD4L is a key enzyme of a BER cascade that operates during seed imbibition, whose deficiency would cause genomic damage detected by DDR, generating a delay or reduction in germination.

Potential of two hydration treatments for improvement of sunflower seed vigour

Seed deterioration is an unavoidable process to which seeds of oilseed plant species such as sunflower are especially sensitive. This study aimed to determine whether different invigoration techniques can improve the attributes of germination in sunflower and alleviate the effects of seed ageing. Both aged and non-aged seeds were subjected to invigoration by pre-soaking with distilled water and with 3% of KH2PO4for 24 hours at 25°C. Germination performance, seedling growth and SDS-PAGE protein profile were determined. The outcome of invigoration depended on the condition of the seeds: invigoration of seeds with both water and KH2PO4reduced the percentage of germination in non-aged seeds, while in aged seeds there was an increase in germination compared to the control. The SDS-PAGE seed protein profiles revealed that the low molecular weight proteins produced high-intensity bands and the high molecular weight proteins were in low concentrations. After accelerated ageing followed by H2O treatment, some bands of proteins appeared in the region of 2S albumins and were associated with a higher percentage of germination. Our results point out that invigoration treatments were more effective in low vigour seeds which can provide wide practical benefits.

Non-Destructive Identification of Naturally Aged Alfalfa Seeds via Multispectral Imaging Analysis.

Seed aging detection and viable seed prediction are of great significance in alfalfa seed production, but traditional methods are disposable and destructive. Therefore, the establishment of a rapid and non-destructive seed screening method is necessary in seed industry and research. In this study, we used multispectral imaging technology to collect morphological features and spectral traits of aging alfalfa seeds with different storage years. Then, we employed five multivariate analysis methods, i.e., principal component analysis (PCA), linear discrimination analysis (LDA), support vector machines (SVM), random forest (RF) and normalized canonical discriminant analysis (nCDA) to predict aged and viable seeds. The results revealed that the mean light reflectance was significantly different at 450~690 nm between non-aged and aged seeds. LDA model held high accuracy (99.8~100.0%) in distinguishing aged seeds from non-aged seeds, higher than those of SVM (87.4~99.3%) and RF (84.6~99.3%). Furthermore, dead seeds could be distinguished from the aged seeds, with accuracies of 69.7%, 72.0% and 97.6% in RF, SVM and LDA, respectively. The accuracy of nCDA in predicting the germination of aged seeds ranged from 75.0% to 100.0%. In summary, we described a nondestructive, rapid and high-throughput approach to screen aged seeds with various viabilities in alfalfa.

Influence of Different Priming Materials on Germination and Alpha-Amylase Enzyme of Hybrids Sorghum (Sorghum bicolor L. Moench. x Sorghum sudanense Staph.) Seeds

Germination is considered a critical step in the development cycle of the plant. But no information is available regarding seed priming with Putrescine, Jasmonic acid, Kinetin, Potassium Nitrate (KNO3), Salicylic acid at a time in the aged and non-aged seeds of sorghum cultivars. However, to know the effect of seed priming with the aforesaid chemicals in the aged and non-aged seeds of sorghum cultivars on the germination rate, germination vigour and alpha-amylase activity, research was conducted under laboratory condition, at Field Crops Central Research Institute, Ankara, Turkey. Aged and unaged seeds of Sugar Grazer II and Digestivo hybrid silage sorghum cultivars were used as the seed material of the experiment. Putrescine, Jasmonic acid, Kinetin, KNO3 and Salicylic acid were used as priming chemicals. The results revealed that aged and un-aged seeds of the cultivars showed different responses to similar chemical and KNO3 application to un-aged seeds had a positive effect on germination rate and alpha-amylase, Whereas Jasmonic acid and Putrescine applications had a positive effect on the aged seeds. Priming with putrescine, KNO3 and jasmonic acid showed the best results in the experiment.

DNA methylation and integrity in aged seeds and regenerated plants

AbstractSeed longevity is a complex process of key ecological and agronomic importance. DNA damage is a significant factor affecting seed ageing. Likewise, epigenetic changes can control gene expression and, therefore, seed response to ageing. The aim of the present work was to investigate the effect of ageing on nucleic acid stability and to identify reliable molecular markers that might help to monitor epigenetic changes within plant genetic resources during conservation. DNA profiles, evaluated by RAPD (random amplified polymorphic DNA), and methylation patterns, obtained by MSAP (methylation-sensitive amplification polymorphism), were compared in non-aged and agedMentha aquaticaseeds and plants produced by them. Germination decreased to 50% by storing seeds at 35°C and 12% wc for 28 days. RAPD profiles were 99% similar in these aged seeds compared to non-aged seeds. However, seedlings produced from the aged seeds showed a 13% dissimilarity compared to seedlings produced from the non-aged seeds. About 8% difference in the MSAP epigenetic profile was detected in seeds after storage and 16% difference was detected in the seedlings produced from them. This indicates that stress from high temperature and humidity during storage induced changes on the methylation state of seeds, and that changes were also detectable in the regenerated plants. Our results suggest that DNA integrity was compromised in seeds during ageing, and on seedlings produced by aged seeds. Genotype screening techniques such as RAPD and MSAP have the potential as markers of nucleic acid stability during seed ageing.

Germinability and seed biochemical properties of susceptible and non–target site herbicide-resistant blackgrass (Alopecurus myosuroides) subpopulations exposed to abiotic stresses

AbstractQuantifying the level of ecophysiological, biochemical, and agronomical fitness of herbicide-resistant (R) and herbicide-susceptible (S) weeds is useful for understanding the evolutionary development of herbicide resistance, but also for implementing herbicide-resistance management strategies. Although germination is a key fitness component in the life cycle of weeds, germinability of S and R weeds has rarely been evaluated under stressful conditions. Germinability traits of S and non–target site resistant subpopulations of blackgrass (Alopecurus myosuroides Huds.) sharing closely related genetic background were tested under salinity, drought stress, and accelerated seed-aging (i.e., exposed to 100% relative humidity at 45 C from 0 to 134 h) conditions. In addition, the activity of three antioxidant enzymes and protein concentration of accelerated aged seeds of the subpopulations were studied. There were no differences in maximum seed germination (Gmax) and time to 50% germination between the two subpopulations under optimum conditions. However, under salinity, drought stress, and accelerated aging conditions, there were differences between the subpopulations. The salinity, drought, and accelerated aging treatments reducing Gmax of the S subpopulation by 50% were 18 dS m−1, 0.75 MPa, and 90 h, respectively, while for the R subpopulation the corresponding values were 15 dS m−1, 0.66 MPa, and 67 h. No differences were found in the activity of the antioxidant enzymes and the content of protein between non-aged seeds of the subpopulations. The aging treatments reducing the activity of catalase and superoxide dismutase enzymes by 50% were 118 and 82 h for the S subpopulation, respectively, while they were 54 and 58 h for the R subpopulation. In contrast, there were no differences in the effect of the aging treatments on the peroxidase activity and protein content between subpopulations. The results provided clear evidence that the non–target site resistant loci of blackgrass is associated with fitness costs under environmental stress.

Influence of artificial ageing test on seed quality changes in Cassia angustifolia Vahl

Deterioration of seed is a complex physiological and biochemical process leading to failure of germination capacity. An experiment was conducted to determine the effects of seed ageing on senna and analyzed the physiological causes for deterioration in artificially aged seeds. The senna seeds were artificially aged for 2,4 and 6 days at 40 ± 10C and 98 ± 2% RH and the non-aged seeds were considered as control. From the results, it is concluded that physiological parameters like germination percentage, hard seed %, root length, shoot length, dry matter production, vigour index gradually decreased and abnormal seedling % and electrical conductivity was increased with increase in period of artificial ageing (two days of ageing to six days of ageing) in senna. The accelerated ageing technique was adopted to precisely predict the storage behaviour of seeds and also artificial ageing conditions (2 days) revealed the beneficial effects to increase the germination percentage (80%) and vigour index (8.8) of seeds. It might be due to breaking the hard seed coat dormancy in the freshly harvested senna seeds.

Differential and interactive effects of cytoplasmic substitution and seed ageing on submergence stress response in wheat (Triticum aestivum L.)

Cytoplasmic genomes affect various phenotypes, including abiotic stress responses, through interaction with nuclear genomes in plants. We focused on the effects of cytoplasmic substitution on germination and seedling growth in combinations with submergence and seed ageing, both of which are known to inhibit these traits posing a challenge in agriculture and seed banking. We carried out comparative phenotypic studies of submergence and seed ageing effects using a series of nucleus–cytoplasm (NC) hybrids of wheat, in which 11 heterologous cytoplasms of Triticum and Aegilops species were combined with a common nucleus. Adopting the test-tube bioassay, germination and seedling growth were studied using aged and non-aged seeds. Imbibed seeds were subjected to 3-days submergence followed by incubation under de-submergence conditions. Seed ageing reduced the germination rates in NC hybrids. Submergence and seed ageing both caused reduction of seedling growth evaluated by shoot length in all or most of the lines. The magnitude of shoot growth inhibition by submergence and seed ageing varied greatly among NC hybrids compared with the nuclear donor, and three distinct response types were recognized. Submergence and seed ageing, in combination, caused leaf chlorosis in most of NC hybrids. Our results suggested that the observed diverse effects of cytoplasmic substitution were exerted through differential interactions with submergence and seed ageing. Further studies are needed to clarify the mechanisms underlying cytoplasmic genome diversity and interaction with nuclear genomes affecting submergence and seed ageing responses in wheat.

NADP-MALIC ENZYME 1 Affects Germination after Seed Storage in Arabidopsis thaliana.

Aging decreases the quality of seeds and results in agricultural and economic losses. The damage that occurs at the biochemical level can alter the seed physiological status. Although loss of viability has been investigated frequently, little information exists on the molecular and biochemical factors involved in seed deterioration and loss of viability. Oxidative stress has been implicated as a major contributor to seed deterioration, and several pathways are involved in protection against this. In this study, we show that seeds of Arabidopsis thaliana lacking a functional NADP-MALIC ENZYME 1 (NADP-ME1) have reduced seed viability relative to the wild type. Seeds of the NADP-ME1 loss-of-function mutant display higher levels of protein carbonylation than those of the wild type. NADP-ME1 catalyzes the oxidative decarboxylation of malate to pyruvate with the simultaneous production of CO2 and NADPH. Upon seed imbibition, malate and amino acids accumulate in embryos of aged seeds of the NADP-ME1 loss-of-function mutant compared with those of the wild type. NADP-ME1 expression is increased in imbibed aged as compared with non-aged seeds. NADP-ME1 activity at testa rupture promotes normal germination of aged seeds. In seedlings of aged seeds, NADP-ME1 is specifically active in the root meristematic zone. We propose that NADP-ME1 activity is required for protecting seeds against oxidation during seed dry storage.

Performance of Iranian Okra Ecotypes Under Various Accelerated Aging Conditions

Knowledge of seed quality and preservation of okra seeds is very limited, and the main purpose of this study was to simulate the condition of seed quality loss during storage and the physiological implications, which has led to seed vigor loss. A factorial experiment was conducted with the aim of studying the mechanism of longevity loss of the three endemic okra ecotypes of Iran (Ahwaz, Isfahan, Mashhad) in response to different accelerated aging durations (24, 48, 96, and 192 h). The accelerated aging condition was incubation of seeds to the temperature of 40 °C with 99% humidity. Germination of okra seeds was improved at 24 and 48 h compared to non-aged seeds, while at 192 h of accelerated aging, seed germination (49%) reduced to 50% of its value in 48 h (96.4%). Our results revealed that Iranian okra ecotypes were able to survive accelerated aging conditions up to 48 h. Antioxidant enzyme activity decreased with the increase in aging durations. Among investigated cultivars, seedling vigor of Mashhad ecotypes was the most sensitive to aging treatments. Our results revealed that the seed reservoir use efficiency value was 66% lower when exposed to 192 h of aging compared to the control. The cultivar Isfahan exhibited the minimum reduction of antioxidant activity, and, interestingly, this ecotype was the most aging tolerant.

Characterization of Aged Lettuce and Chard Seeds by Photothermal Techniques

In this study, photoacoustic spectroscopy (PAS) was used as an option to evaluate aging in vegetable seeds. Aged seeds were characterized by their decrease in germination and vigor, which are important quality measures to obtain healthy and uniform crops. The seed optical parameters obtained with this technique provide information about their composition and physiological quality attributes. Red lettuce and chard seeds, aged and non-aged, were used for these experiments. The thermal diffusivity (α) and optical absorption coefficient (β) were determined for a large number of aged and non-aged seeds. In the case of β, this optical parameter was obtained in the spectral range from 250 nm to 750 nm. The results show statistically significant differences in β values for both types of seeds, with higher values found for non-aged specimens. Also images of scanning electron microscopy for aged and non-aged seeds corroborate marked differences between them. This PAS approach represents a promising method to be applied in the evaluation of seed quality in the food industry.

Genes for seed longevity in barley identified by genomic analysis on near isogenic lines.

Genes controlling differences in seed longevity between 2 barley (Hordeum vulgare) accessions were identified by combining quantitative genetics "omics" technologies in near isogenic lines (NILs). The NILs were derived from crosses between the spring barley landraces L94 from Ethiopia and Cebada Capa from Argentina. A combined transcriptome and proteome analysis on mature, nonaged seeds of the 2 parental lines and the L94 NILs by RNA-sequencing and total seed proteomic profiling identified the UDP-glycosyltransferase MLOC_11661.1 as candidate gene for the quantitative trait loci on 2H, and the NADP-dependent malic enzyme (NADP-ME) MLOC_35785.1 as possible downstream target gene. To validate these candidates, they were expressed in Arabidopsis under the control of constitutive promoters to attempt complementing the T-DNA knockout line nadp-me1. Both the NADP-ME MLOC_35785.1 and the UDP-glycosyltransferase MLOC_11661.1 were able to rescue the nadp-me1 seed longevity phenotype. In the case of the UDP-glycosyltransferase, with high accumulation in NILs, only the coding sequence of Cebada Capa had a rescue effect.

Ageing-regulated changes in genetic integrity of two recalcitrant seeded species having contrasting longevity

Storage longevity of two contrasting recalcitrant seeded species was studied relative to oxidative metabolism and DNA damage under ambient storage (25 ± 2 °C, 50 ± 2% relative humidity). The present study was aimed to investigate the ageing-induced amendments in two recalcitrant seeded species, Madhuca latifolia and Shorea robusta. These are economically important tropical trees and are exploited extensively in commercial sectors. Fresh seeds of M. latifolia and S. robusta lost their germinability within 35 and 8 days after harvest, respectively, under ambient storage (temperature 25 ± 2 °C, relative humidity 50 ± 2%). To untangle the possible mechanisms involved in deteriorative changes in respective seeds, levels of reactive oxygen species (ROS) and changes in DNA content, oxidation, fragmentation and polymorphism, and DNase activity were monitored. The results revealed significant (2.1–7.3 folds) upsurge in ROS levels in these seeds. In contrast, remarkable fall in DNA content of embryonic axes (3.8 fold and twofold) and cotyledons (6.7 fold and twofold) of M. latifolia and S. robusta seeds, respectively, were observed. Moreover, enhanced oxidation (8.9–18.8 fold) and fragmentation (2.1–2.8 fold) of DNA along with increased (9.9–25.3 fold) DNase activity were observed in axes and cotyledons of respective seeds, revealing active participation of ROS in oxidation (r = 0.96, p < 0.05), and of DNase in fragmentation (r = 0.94, p < 0.05) of DNA. Dendrogram of RAPD unveiled significant alterations in similarity coefficients of aged and non-aged seeds of both the species. Thus, overall results concluded that loss of viability of M. latifolia and S. robusta seeds was closely associated with ageing related changes such as over accumulation of ROS, fall in DNA content, increased oxidation, fragmentation and DNA polymorphism, and DNase activity.

Effect of moisture content on vigor of Cyathula officinalis seeds and its anti-aging mechanism analysis

Effects of nine different moisture contents on vigor of Cyathula officinalis seeds and its anti-aging mechanism were studied by artificial accelerated aging through high temperature and wet. The research results showedthat seed vigor were generally decreased after artificial aging; in general, seed vigor and its anti-aging ability are relatively stronger within the scope of 6.55%-4.78% moisture content, the increase range of seed conductivity, peroxidase activity, malondialdehyde content,and reduce amplitude of activityof dehydrogenase , superoxide dismutaseare alllower as well. And when the moisture content reduced to 5.77%, all of the germination tests index of the non-aged seeds are the highest, and the activity of peroxidase the lowest,conductivity of leaching solution relatively low, activity of dehydrogenase and superoxide dismutase the highest,and catalase activityrelatively high.Therefore, in the low temperature germplasm preservation of C. officinalis seeds, the seed moisture content should be controlled close to the range of (5.70±1)% to keep higher vigor and anti-aging ability.

Leakage of inorganic compounds from artificially-aged radish (Raphanus sativus L.) and Chinese cabbage (Brassica rapa ssp. pekinensis) seeds and use of phosphate leakage from single seed as a tool for assessing viability

Inorganic compounds, Ca, Mg, P, Na, K, B, Mo, Mn, Cu, Fe and Zn, in the seed leachate of artificiallyaged (AA) seeds from three cultivars of radish (Raphanus sativus L.) and Chinese cabbage (Brassica rapa ssp. pekinensis) seeds were measured and compared to those of non-aged (NA) seeds, and a technique to detect phosphate leakage from the leachate from single seeds was developed as a tool for assessing viability. K leached out in much greater quantities than other elements in both NA and AA seeds, followed by P, Na, Ca, Mg, and B in the AA seeds. The Mn and Cu were not detected in any cultivars, while Mo and Fe in Chinese cabbage seeds and Zn in radish seeds were only present in trace amounts of leachate from AA seeds. In general, K, P, Na, Ca, Mg, and B leakage occurred in large amounts from AA seeds relative to NA seeds, though there were different ratios of AA to NA seeds. Evaluation of the ratio of AA to NA seeds of inorganic compound leakage revealed that P was greatest, followed by Mg, K, Na and Ca. A spectrophotometric determination of phosphate from single seed leachate was developed using multi-plate reader. This technique is simple, fast, nondestructive and inexpensive, and applicable to many individual seeds at one time. The relationships between percent germination and absorbance (630 nm) of the single seed leachate with phosphate leakage from Chinese cabbage and radish seeds that had been artificially aged to give various viability levels appeared to have very high negative correlations. In conclusion, phosphate detection from single seed leakage could provide a valuable and practical tool for assessing seed viability.

Effects of salt priming on seedling vigor and field establishment of aged winter wheat seeds

A sub-sample of winter wheat (Triticum aestivum L. cv. Zarin) seeds was kept as high vigor seed lot and two other sub-samples were aged at 40°C for 7 and 9 days. Then, each seed lot was divided into three sub-samples, one of which was kept as control (non-primed) and two other samples were soaked in 1% KNO3 and KH2PO4 solutions for 8 hours at 20±1oC. Laboratory and field studies were arranged as factorial based on CR and RCB designs, respectively. Mean germination rate and percentage, seedling dry weight and length and field emergence rate significantly decreased with increasing seed ageing. All these traits, except germination percentage, were significantly improved by salt priming of seeds. Salt priming of both aged and non-aged seeds also enhanced seedling emergence percentage in the field. In most cases, no significant differences between KNO3 and KH2PO4 priming were found. Therefore, both priming techniques can improve seedling vigor and field establishment of winter wheat.

HEAT SHOCK TREATMENT CAN IMPROVE SOME SEED GERMINATION INDEXES AND ENZYME ACTIVITY IN PRIMED SEEDS WITH GIBBERELLIN OF MOUNTAIN RYE (SECALE MONTANUM) UNDER ACCELERATED AGING CONDITIONS

ABSTRACT Seed priming with gibberellin (GA) enhances seed germination performance; but the quality of primed seeds in aging condition often reduces more than non-primed seeds. An experiment was conducted to evaluate the effect(s) of heat shock treatments on germination characteristics and enzyme activity of primed mountain rye (Secale montanum) seeds with gibberellin under accelerated aging. Heat shock treatments, can substantially decrease the speed of quality reduction of mountain rye (Secale montanum) primed seeds. In primed seeds with gibberellin, which has non-aged, the highest germination percentage (GP) and normal seedling percentage (NSP) was attained from heat shock treatment at 35°C for 3 h, also after 3 days aging, it was attained from heat shock treatment at 35°C for 3 h. After 3 days of aging the highest germination index (GI) was attained from unprimed seeds, but no significant difference with heat shock treatment at 35°C for 3 h. The minimum means time germination (MTG) was in heat shock treatment at 30°C for 3 h in non-aged seeds. After 3 days of aging, heat shock treatment reduce MTG as compared to the primed seeds. Heat shock treatment at 35°C for 3 h increased seed vigor index (SVI) as compared to the unprimed and primed seed in non-aged seeds and after 3 days aging. Seedling length (SL) increases with heat shock treatment at 30°C for 4 h in non-aged seeds as compared to the primed and unprimed seeds, but after 3 days of aging heat shock treatment except at 35°C for 3 h and 40°C for 4 h reduced SL as compared to the primed and unprimed seeds. Also, heat shock treatments increase some antioxidant enzymes [Catalase (CAT), Ascorbat peroxidase (APX)].

Ação do ácido ascórbico exógeno na qualidade fisiológica de sementes de feijão de corda envelhecidas artificialmente

The aim of this study was to evaluate the effects of pre-treatment and post-treatment with ascorbic acid in reducing the damage caused by aging in cowpea seeds, which were aged in artificial accelerated aging chamber (45°C, 99% relative humidity in the dark) for 72 h and it were subjected to four treatments: T1 – non-aged seeds were not treated with ascorbic acid (AsA); T2 – non-aged seeds treated with AsA; T3 – seeds before aging were subjected to a treatment with AsA to 0.85 mM; T4 – seeds after aging were subjected to a treatment with a 0.85 mM AsA. The aging of seeds for 72 h (T2) caused significant damage in the cell membranes of cowpea seeds, as evidenced by a increase in electrolyte leakage, higher level of lipid peroxidation and a lower germination percentage, when compared with the control (T1). T4 results were like the control treatment, with a lower electrolyte leakage and lipid peroxidation, well as a higher germination percentage, when compared with T2. The exogenous application of 0.85 mM ascorbic acid in cowpea seeds after artificial aging can mitigate its detrimental effects on the membranes integrity and seed physiological quality.

Ação do ácido ascórbico exógeno na qualidade fisiológica de sementes de feijão de corda envelhecidas artificialmente

O objetivo desse estudo foi avaliar os efeitos do pre e pos-tratamento com acido ascorbico na reducao dos danos ocasionados pelo envelhecimento em sementes de feijao de corda, as quais foram envelhecidas em câmara de envelhecimento artificial (45 oC, 99% U.R., no escuro) por 72 h, sendo submetidas a quatro tratamentos: T1 – sementes nao envelhecidas e nao tratadas com acido ascorbico (AsA); T2 – sementes envelhecidas e nao tratadas com AsA; T3 – sementes que antes do envelhecimento foram submetidas a um tratamento com AsA a 0,85 mM; T4 – sementes que apos o envelhecimento foram submetidas a um tratamento com AsA a 0,85 mM. O envelhecimento das sementes por 72 h (T2) provocou danos significativos nas membranas celulares das sementes de feijao de corda, como foi evidenciado pelo aumento no vazamento de eletrolitos, maior nivel de peroxidacao de lipidios e menor porcentagem de germinacao quando comparado com o controle (T1). O T4 conseguiu igualar aos resultados apresentados pelo controle, apresentando um menor vazamento de eletrolitos e peroxidacao de lipidios, bem como maior germinacao, quando comparado com o T2. A aplicacao exogena de acido ascorbico a 0,85 mM nas sementes de feijao de corda apos o envelhecimento artificial pode atenuar efeitos deleterios na integridade de membranas e favorecer a qualidade fisiologica das sementes.

Accelerated aging of ipê seeds under controlled conditions of storage

This research was aimed at studying effects of storage and accelerated aging on germination and profile of storage proteins in Handroanthus albus seeds. These were stored into a cold chamber (± 8 ºC; RH ± 40%) and after periods of 0, 3, 6, 9, and 12 months of storage, were subjected to accelerated aging for 0, 24, 48, 72, and 96 hours. Relationships between germination and proteins profile were assessed. Germination test was performed at 25 ºC, under constant light. For protein extraction, 125 mg of seeds were macerated in 2 mL of extraction buffer (1M Tris-HCl; pH 8.8) and applied to SDS-PAGE polyacrylamide gel at 80 V .15 h-1. Twelve month storage, combined with 72 hours accelerated aging have increased germination in approximately 65% when compared to non-aged seeds or to seeds with 24 h of accelerated aging. Besides beneficial effects, degradation and synthesis of different proteins were observed. It was concluded that germination of Handroanthus albus seeds, when not subjected to accelerated aging, is favored by storage in cold chamber during three to six months, or from nine to 12 months when subjected to accelerated aging process. Storage proteins may be associated to those increases, and hence further studies are needed.