Resumo -O objetivo deste trabalho foi avaliar os padrões eletroforéticos das proteínas resistentes ao calor e a atividade da enzima endo-β-mananase durante a germinação de sementes de alface, em alta temperatura. Sementes de oito cultivares de alface foram submetidas aos testes de germinação, primeira contagem e emergência em duas temperaturas, 20 e 35 o C. Foram calculados o índice de velocidade de germinação (IVG) e o índice de velocidade de emergência (IVE). Avaliou-se, também, a expressão das proteínas resistentes ao calor e da enzima endo-β-mananase, para todos os tratamentos. Utilizou-se o delineamento experimental inteiramente casualizado, em arranjo fatorial 2x8, com duas temperaturas e oito cultivares. A maior germinação é observada a 35 o C na cultivar Everglades, considerada termotolerante. Os padrões de proteínas resistentes ao calor em sementes de alface apresentam bandas específicas na cultivar Everglades, a 35ºC. A atividade da enzima endo-β-mananase é maior na cultivar Everglades, nessa temperatura. Essa cultivar tem potencial para utilização em programas de melhoramento de alface com vistas à tolerância a altas temperaturas durante a germinação.Termos para indexação: Lactuca sativa, endo-β-mananase, proteínas tolerantes ao calor, termoinibição. Physiological and biochemical aspects of lettuce seed germination at different temperaturesAbstract -The objective of this work was to evaluate the electrophoretic patterns of heat-tolerant proteins and the activity of the endo-β-mannanase enzyme during lettuce seed germination, at high temperature. Seeds of eight lettuce cultivars were subjected to germination, first count, and emergence tests at two temperatures, 20 and 35°C. The index of germination speed (IVG) and the emergence rate index (IVE) were calculated. The expression of heat-tolerant proteins and of the endo-β-mannanase enzyme was also evaluated for all treatments. The experimental design was completely randomized, in a 2x8 factorial arrangement, with two temperatures and eight cultivars. The highest germination is observed at 35°C in the Everglades cultivar, considered thermotolerant. The patterns of heat-tolerant proteins in lettuce seeds present specific bands in the Everglades cultivar, at 35ºC. The activity of the endo-β-mannanase enzyme is higher in the Everglades cultivar, at this temperature. This cultivar has potential for use in lettuce breeding programs aiming for tolerance to high temperatures during germination.

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The aim of this study was to evaluate seed physiological quality and initial pea (Pisum sativum) seedling development at different water and salt potentials. Polyethylene glycol 6000, sodium chloride and potassium chloride solutions with different osmotic potentials (0; -0.2; -0.4; -0.6; -0.8; -1.0, and -1.2 MPa) were used, and the experiment had a 3 × 7 factorial arrangement. The physiological quality and initial seedling growth characteristics (first germination count, final germination count, strong normal seedlings, epicotyl and taproot lengths, epicotyl dry matter, and root dry matter) were evaluated in a completely randomized experimental design, with four repetitions. Decreases in the observed variables showed that the simulated stress conditions negatively affected physiological performance, germination and initial seedling growth. The water and salt stresses induced by the sodium chloride and potassium chloride solutions were greater than the stress induced by polyethylene glycol 6000.

ABSTRACT. The aim of this study was to characterize maize lines tolerant to cold temperatures during the germination process. Seeds from lines with different levels of tolerance to low temperatures were used; 3 lines were classified as tolerant and 3 as susceptible to low germination temperatures. A field was set up to multiply seeds from selected lines. After the seeds were harvested and classified, we conducted physiological tests and analyzed fatty acid content of palmitic, stearic, oleic, linoleic, linolenic, and eicosenoic acids. In proteomic analysis, the expression of heat-resistant proteins, including catalase, peroxidase, esterase, superoxide dismutase, and α-amylase, were evaluated. Transcript analysis was used to measure the expression of the genes AOX1, AOX2, ZmMPK-17, and ZmAN-13. The material showing the highest susceptibility to low germination temperatures contained high saturated fatty acid content. Expression of α-amylase in seeds soaked for 72 h at a temperature of 10°C was lower than expression of α-amylase when soaked at 25°C for the same amount of time. We observed variation in the expression of heat-resistant proteins Gene expression related to temperature tolerance in maize in seeds of the lines evaluated. The genes AOX and Zm-AN13 were promising for use in identifying maize materials that are tolerant to low germination temperatures.

-This present study aimed to assess seed quality of popcorn seedlings subjected to low temperatures by examining their physiological changes, enzymes, and images. We used a completely randomized design with four replications in a factorial arrangement with four hybrids (P618, AP6002, AP8202, AP8203) and five temperatures (10, 13, 16, 19 and 25 °C). Their physiological quality was assessed through radicle protrusion, germination, dry mass of seedlings and emergence. We have assessed the images of seedlings through their hypocotyl and root lengths; and through rates of automatic force, uniformity and growth, provided by Groundeye. The isozyme expressions were determined for the catalase (CAT -IUBMB: EC 1.11.1.6), alcohol dehydrogenase (ADH -IUBMB: EC 1.1.1.1), malate dehydrogenase (MDH -IUBMB: EC: 1.1.1.37) and α-amylase (α-AMY -IUBMB: EC 3.2.1.1). Results show that low temperatures cause a negative effect on seed physiological quality in enzyme expression of CAT, ADH, MDH and α-AMY and on the performance of seedlings. These alterations compromise seed quality. Hybrids AP6002 and AP8203 should be recommended for sowing at up to 16 °C. The Groundeye software was efficient in the analysis of popcorn seedlings and in for the assessment of seed quality when submitted to low temperatures.

Despite the insufficient internal supply of popcorn kernel cultivars, the Brazilian production is continuously increasing. Therefore, searching for tests that offer fast results and reliable information on the physiological potential of the seeds is very important. The objective of this study was to assess the efficiency of the accelerated aging test, by using different times and exposure temperatures, for the evaluation of the physiological quality of popcorn seed lots. Popcorn seeds from three lots of the hybrid AP 8203 were used. For the initial characterization of the lots, the following tests were conducted: seed moisture content, first and final germination count, and field emergence. The accelerated aging test was performed in a 3x4x2 factorial scheme. After aging, the seeds were tested for moisture content, germination, and electrical conductivity. The experiment was carried out in a completely randomized design. The characteristic vigor was affected during aging, as evidenced by the increase in the amount of leachate detected by the electrical conductivity test. Seed lot 3 was most vigorous in the aging test conducted for 48 h at 45 °C. The accelerated aging test at 42 ºC for 48 h provides consistent information to differentiate seed lots of popcorn.

ABSTRACT. Seed germination and dormancy are complex phenomena that are controlled by many genes and environmental factors. Such genes are indicated by phytohormones that interact with each other, and may cause dormancy or promote seed germination. The objective of this study was to investigate gene expression associated with the biosynthetic pathways of abscisic acid (ABA), gibberellic acid (GA), and ethylene (ET) in dormant and germinated lettuce seeds. The expressions of LsNCED, LsGA3ox1, and ACO-B were evaluated in germinating and dormant seeds from the cultivars Everglades, Babá de Verão, Verônica, Salinas, Colorado, and Regina 71. The expressions of LsNCED, LsGA3ox1, and ACO-B were related to the biosynthesis of ABA, GA, and ET, respectively; therefore, the presence of these substances depends on genotype. LsNCED expression only occurred in dormant seeds, and was connected to dormancy. LsGA3ox1expression only occurred in germinated seeds, and was connected to germination. The ACO-B gene was involved in ET biosynthesis, and was expressed differently in germinated and dormant seeds, depending on the genotype, indicating different functions for different characteristics. Furthermore, sensitivity to phytohormones appeared to be more important than the expression levels of LsNCED, LsGA3ox1, or ACO-B.

ABSTRACT. In this study, we analyzed heterosis, amylase enzyme gene expression, and the physiological quality of maize seeds with different genotypes and sizes, which were subjected to aging and not subjected to aging. We used seeds from 2 maize lines that differed with regard to physiological quality, the hybrid, and the reciprocal hybrid; they were classified into 2 sizes and were subjected to aging and not subjected to aging. Physiological quality was assessed by performing tests for germination, emergence, emergence speed index, and artificial aging. Expressions of the genes alpha amylase B73, alpha amylase (LOC542522), isoamylase mRNA clone 353244, and the endogenous controls ubiquitin and alcohol dehydrogenase in the seeds were studied using quantitative real-time-polymerase chain reaction. We observed heterosis for seed quality and for expression of amylase genes in the G.E. Oliveira et al. 8624©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 14 (3): 8623-8633 (2015) genotypes studied. We found no difference in seed quality between large and small seeds.