Histogenesis and reserve dynamics during the maintenance of dormancy and germination in seeds of the basal palm Mauritiella armata.

The germination and post-seminal development of Arecaceae are notably complex due to the microscopic dimensions of the embryonic axis, the occurrence of dormancy, and the diversity of reserve compounds. In-depth information on this subject is still limited, especially in terms of the basal sub-family Calamoideae. Mauritiella armata is widely distributed in the Amazon region and is considered a key species in flooded ecosystems (veredas) in the Cerrado biome. We sought to describe histogenesis and reserve compound dynamics during the germination of M. armata, as well as the changes in incubated seeds over time. Seeds with their operculum removed (the structure that limits embryonic growth) were evaluated during germination using standard methods of histology, histochemistry, and electron microscopy. Evaluations were also performed on intact seeds incubated for 180 days. The embryos show characteristics associated with recalcitrant seeds of Arecaceae: a high water content (>80%), differentiated vessel elements, and reduced lipid reserves. Both the embryo and endosperm store abundant reserves of proteins, neutral carbohydrates, and pectins. The completion of germination involves cell divisions and expansions in specific regions of the embryo, in addition to the mobilization of embryonic and endospermic reserves through symplastic and apoplastic flows. Intact seeds show dormancy (not germinating for 180 days), but exhibit continuous development associated with cell growth, differentiation, and reserve mobilization. The anatomical and histochemical characters of M. armata seeds indicate an association between recalcitrance and dormancy related to the species' adaptation to flooded environments.

O tamanho de sementes de feijão afeta a utilização das reservas armazenadas durante a germinação / Seed size of common bean affects the utilization of stored reserves during germination

O objetivo do presente estudo foi avaliar a qualidade fisiológica de sementes defeijão com diferentes tamanhos, identificando a relação do tamanho da semente com a mobilização e utilização de reservas. Foram utilizadas sementes da cultivar comercial IPR-88 Uirapuru e Iapar 81 padronizadas e posteriormente, determinadas três frações a partir de pesagem individual, sendo: sementes pequenas, médias e grandes. A qualidade fisiológica das três frações foi determinada pelo teste de germinação e pelos testes de vigor: envelhecimento acelerado e teste de desempenho de plântulas (comprimento). A mobilização e utilização de reservas foi mensurada aos cinco dias de hidratação das sementes, onde foram avaliadas massa seca, taxa de mobilização de reservas, taxa de redução de reservas e eficiência de uso das reservas. Os resultados demonstraram que não houve diferença entre as frações na porcentagem de germinação e envelhecimento acelerado. Considerando os parâmetros que avaliaram a mobilização e utilização de reservas, verificou-se que sementes de maior tamanho formam plântulas de maior massa seca, no entanto, tem menor taxa de mobilização de reservas e menor eficiência de uso de suas reservas. Desta forma, evidencia-se que o tamanho da semente influencia a mobilização e utilização de reservas, de maneira que sementes da fração média e pequena apresentam maior eficiência de uso de reservas até os cinco dias de germinação.(AU)

The objective of the present study was to evaluate the physiological quality of bean seeds with different sizes, identifying the relationship of seed size with the mobilization and utilization of reserves in bean seeds. Seeds of the commercial cultivarIPR-88 Uirapuru and Iapar 81 were standardized and subsequently, three fractions were determined from individual weighing, being: small medium and large seeds. The physiological quality of the three fractions was determined by germination test, accelerated aging vigor test, and seedling performance (length) test. Reserve mobilization and utilization was measured at five days of seed hydration, where dry mass, reserve mobilization rate, reserve reduction rate, and reserve use efficiency were evaluated. The results showed that there was no difference between the fractions in the percentage of germination and accelerated aging. Considering the parameters that evaluated the mobilization and use of reserves, it was found that larger seeds form seedlings with greater dry mass, however, have lower rate of reserve mobilization and lower efficiency of use of their reserves. Thus, it is evident that the size of the seed influences the mobilization and use of reserves, so that seeds of the medium and small fraction present higher reserve use efficiency at five days of germination.(AU)

Morphostructural and histochemical dynamics of Euterpe precatoria (Arecaceae) germination.

The fruits of Euterpe precatoria, popularly known as açaí palm, have been commercially exploited for use in food and beverages because of their medicinal and energetic properties. However, despite the growing demand, little is known about the seeds germination, until now, its main form of propagation. In this context, we have characterized the structure of the zygotic embryo and described temporally the germination process of E. precatoria with emphasis on the morpho-anatomical and histochemical aspects. For this end, we have collected and analyzed zygotic embryo and seedlings samples before sowing and at different periods after sowing-2, 4, 6, 8, 10, 15, 20, 30, 40, 50, and 60 days. The embryo has an oblique embryonic axis and mainly protein reserves. Seed germination is classified as cryptocotyledonar, hypogeal, and adjacent ligular and we observed seedlings at 20 days after sowing (33.3%), although anatomical evidence of the beginning of the germination process have been observed at 15 days. The day-20 was histologically marked by the expansion of the ligule, beginning of second eophyll differentiation, and complete root protrusion. This stage was characterized by the total consumption of protein reserves and increased starch grains. The occurrence of 100% of root and ligula emission was verified at day-60, which characterizes a slow and heterogeneous process. The morphological marker of the E. precatoria germination is the exit of the proximal region (cotyledonary petiole) of the embryo from within the seed by the lifting of the operculum and the species has some peculiarities, such as the presence of high concentrations of phenolic compounds and idioblasts before and throughout the germination process, and starch grains located on the embryonic axis. We can verify that the consumption of protein reserves of the embryo is related to the energy supply necessary for root protrusion.

Cytological and histochemical evaluations reveal roles of the cotyledonary petiole in the germination and seedling development of Mauritia flexuosa (Arecaceae).

The cotyledonary petiole (CP) completely envelops the embryo axis during embryogenesis in Arecaceae. There is little information available, however, on the roles of that structure in seed germination and initial seedling development-crucial plant life cycle phases. The study therefore sought to evaluate the roles of CP in the germination and post-seminal development of the recalcitrant seeds of Mauritia flexuosa, an ecologically and economically important neotropical palm. The CP and the embryo/vegetative axis were evaluated during germination and initial seedling development using standard morphological, anatomical, histochemical, and ultrastructural methodologies. Evaluations of dormant seeds incubated for 60 days were also performed. The CP (a) promotes seedling protrusion in the germination, extending the embryo axis outside the seed; (b) protects the vegetative axis through the development of coating rich in phenolic compounds and lignin; (c) participates in reserve translocation, with the conversion of its own proteinaceous/mucilaginous reserves into transitional starch, as well as acting in the transport of endospermic reserves; (d) favors aeration, with the formation of pathways among stomata, substomatal chambers, and intercellular spaces; (e) controls seedling morphogenesis by modulating the curvature of the vegetative axis; and (f) contributes to overcoming seed bank dormancy through cytological alterations (protein synthesis and mitochondrial proliferation). The cotyledonary petiole of palms is a unique and multifunctional structure among angiosperms, with crucial roles in germination and seedling establishment.

Cellular and molecular changes associated with competence acquisition during passion fruit somatic embryogenesis: ultrastructural characterization and analysis of SERK gene expression.

The integration of cellular and molecular data is essential for understanding the mechanisms involved in the acquisition of competence by plant somatic cells and the cytological changes that underlie this process. In the present study, we investigated the dynamics and fate of Passiflora edulis Sims cotyledon explants that were committed to somatic embryogenesis by characterizing the associated ultrastructural events and analysing the expression of a putative P. edulis ortholog of the Somatic Embryogenesis Receptor-like Kinase (SERK) gene. Embryogenic calli were obtained from zygotic embryo explants cultured on Murashige and Skoog medium supplemented with 2,4-dichlorophenoxyacetic acid and 6-benzyladenine. Callus formation was initiated by the division of cells derived from the protodermal and subprotodermal cells on the abaxial side of the cotyledons. The isodiametric protodermal cells of the cotyledon explants adopted a columnar shape and became meristematic at the onset of PeSERK expression, which was not initially detected in explant cells. Therefore, we propose that these changes represent the first observable steps towards the acquisition of a competent state within this regeneration system. PeSERK expression was limited to the early stages of somatic embryogenesis; the expression of this gene was confined to proembryogenic zones and was absent in the embryos after the globular stage. Our data also demonstrated that the dynamics of the mobilization of reserve compounds correlated with the differentiation of the embryogenic callus.

Quantification of storage proteins during seed imbibition of native species from the brazilian caatinga vegetation / Quantificação de proteínas de reserva durante a embebição de sementes de espécies nativas da caatinga

Poincianella pyramidalis (Fabaceae), Schinopsis brasiliensis (Anacardiaceae) and Sideroxylon obtusifolium (Sapotaceae) are native species of the Caatinga vegetation from northeastern Brazil and have both biological importance and potential economic uses. Little is known about the water uptake and degradation of storage proteins during seed germination of these species. The aim of this study was to evaluate the imbibition and quantify the amount of storage proteins during seed germination of P. pyramidalis, S. brasiliensis and S. obtusifolium. Two lots of S. obtusifolium seeds with different vigour were used. Four replicates of 20 seeds of P. pyramidalis, S. brasiliensis and S. obtusifolium, were sown onto gerboxes with blotting paper soaked in distilled water and incubated during 72, 200 and 624 hours. Before and after imbibition seeds were weighed and frozen at until the sequential extraction and analysis of the seed storage proteins. Based on our results, we conclude that seed germination of P. pyramidalis, S. brasiliensis and S. obtusifolium has a well-defined triphasic imbibition. All storage proteins content of P. pyramidalis and S. brasiliensis seeds degraded along with the seed imbibition. Likewise, the content of albumins, globulins and glutelins decreased as S. obtusifolium seeds absorbed water.

Poincianella pyramidalis (Fabaceae), Schinopsis brasiliensis (Anacardiaceae) e Sideroxylon obtusifolium (Sapotaceae) são espécies nativas da Caatinga e que apresentam grande importância biológica e potencial econômico. Pouco se sabe sobre a absorção de água e degradação de proteínas de reserva durante a germinação dessas espécies. O objetivo deste trabalho foi avaliar a embebição e quantificação de proteínas de reserva durante o processo germinativo de sementes de P. pyramidalis, S. brasiliensis and S. obtusifolium. Dois lotes de sementes de S. obtusifolium de vigor diferente foram utilizados. Quatro repetições de 20 sementes de P. pyramidalis, S. brasiliensis e S. obtusifolium, foram colocados em gerbox com papel germitest umedecido com água destilada e incubados durante 72, 200 e 624 horas. Antes e após a embebição as sementes foram pesadas até a extração sequencial e quantificação de proteínas de reserva. A germinação das sementes de P. pyramidalis, S. brasiliensis e S. obtusifolium tem um padrão de embebição trifásico bem definido. Assim, podemos concluir que a germinação das sementes de P. pyramidalis, S. brasiliensis e S. obtusifolium apresenta modelo trifásico na embebição bem definido. O conteúdo de proteínas de reserva de P. pyramidalis e S. brasiliensis degrada na medida em que suas sementes embebem. Os teores de albuminas, globulinas e glutelinas reduzem na medida em

Quantification of storage proteins during seed imbibition of native species from the brazilian caatinga vegetation / Quantificação de proteínas de reserva durante a embebição de sementes de espécies nativas da caatinga

Poincianella pyramidalis (Fabaceae), Schinopsis brasiliensis (Anacardiaceae) and Sideroxylon obtusifolium (Sapotaceae) are native species of the Caatinga vegetation from northeastern Brazil and have both biological importance and potential economic uses. Little is known about the water uptake and degradation of storage proteins during seed germination of these species. The aim of this study was to evaluate the imbibition and quantify the amount of storage proteins during seed germination of P. pyramidalis, S. brasiliensis and S. obtusifolium. Two lots of S. obtusifolium seeds with different vigour were used. Four replicates of 20 seeds of P. pyramidalis, S. brasiliensis and S. obtusifolium, were sown onto gerboxes with blotting paper soaked in distilled water and incubated during 72, 200 and 624 hours. Before and after imbibition seeds were weighed and frozen at until the sequential extraction and analysis of the seed storage proteins. Based on our results, we conclude that seed germination of P. pyramidalis, S. brasiliensis and S. obtusifolium has a well-defined triphasic imbibition. All storage proteins content of P. pyramidalis and S. brasiliensis seeds degraded along with the seed imbibition. Likewise, the content of albumins, globulins and glutelins decreased as S. obtusifolium seeds absorbed water.

Poincianella pyramidalis (Fabaceae), Schinopsis brasiliensis (Anacardiaceae) e Sideroxylon obtusifolium (Sapotaceae) são espécies nativas da Caatinga e que apresentam grande importância biológica e potencial econômico. Pouco se sabe sobre a absorção de água e degradação de proteínas de reserva durante a germinação dessas espécies. O objetivo deste trabalho foi avaliar a embebição e quantificação de proteínas de reserva durante o processo germinativo de sementes de P. pyramidalis, S. brasiliensis and S. obtusifolium. Dois lotes de sementes de S. obtusifolium de vigor diferente foram utilizados. Quatro repetições de 20 sementes de P. pyramidalis, S. brasiliensis e S. obtusifolium, foram colocados em gerbox com papel germitest umedecido com água destilada e incubados durante 72, 200 e 624 horas. Antes e após a embebição as sementes foram pesadas até a extração sequencial e quantificação de proteínas de reserva. A germinação das sementes de P. pyramidalis, S. brasiliensis e S. obtusifolium tem um padrão de embebição trifásico bem definido. Assim, podemos concluir que a germinação das sementes de P. pyramidalis, S. brasiliensis e S. obtusifolium apresenta modelo trifásico na embebição bem definido. O conteúdo de proteínas de reserva de P. pyramidalis e S. brasiliensis degrada na medida em que suas sementes embebem. Os teores de albuminas, globulinas e glutelinas reduzem na medida em

Condición corporal, perfil de lipoproteínas y actividad ovárica en vacas Holstein en lactancia temprana / Body Condition, lipoprotein profiles and ovarian activity in Holstein cows during early lactation

Con el objetivo de conocer el efecto de la condición corporal, al momento del parto, sobre el balance de energía, la pérdida de peso, el perfil de lipoproteínas y la actividad ovárica en el posparto temprano, se evaluó un grupo de 10 vacas de la raza Holstein del Hato Paysandú de la Universidad Nacional, sede Medellín, en el día del parto y a los días 10, 20, 30, 40 y 50 días posparto para determinar el peso, la condición corporal, la producción de leche y los valores plasmáticos de colesterol total, lipoproteína de muy baja densidad (VLDL), lipoproteína de baja densidad (LDL) y lipoproteína de alta densidad (HDL). Adicionalmente, los animales fueron sometidos a ecografía ovárica para determinar el número y el tamaño de los folículos presentes en cada muestreo, así como la presencia de cuerpo lúteo. Con una frecuencia mensual se analizaron químicamente los componentes de la dieta para establecer los aportes de nutrientes. Sólo se presentaron diferencias significativas para el cambio de peso en el intervalo entre el parto y el día 10 posparto, con respecto a los demás intervalos, siendo este el periodo con las mayores pérdidas de peso. El balance de energía osciló entre 3 y 18% de los requerimientos al momento del parto y de -22 a -9 % de los requerimientos para los demás períodos de muestreo. En cuanto al perfil lipídico las variables que presentaron diferencias estadísticamente significativas fueron: colesterol, LDL y HDL; los valores aumentaron conforme aumentaban los días en lactancia. Por el contrario, para triglicéridos y VLDL los valores aumentaron hasta los cuarenta días y disminuyeron al día 50 posparto. No se encontraron diferencias significativas entre las poblaciones de folículos en función de los períodos de muestreo. Sólo seis vacas presentaron ovulación durante el periodo observado.

A group of 10 Holstein cows from Paysandú herd (Universidad Nacional de Colombia, sede Medellín), were evaluated at the expected calving day and over 10, 20, 30, 40 and 50 postpartum days, to determine body weight, BCS, milk yield and blood serum values of total cholesterol and lipoproteins (VLDL, LDL and HDL) in order to analyze the effect of Body Condition Score (BCS) at parturition on energy balance, weight loss, lipoprotein profiles and the ovarian activity in early postpartum.  Additionally, an ovarian ultrasonogram was performed to determinate follicle number and size, as well as the presence of corpora lutea. The composition of the diet was chemically analyzed monthly.  There were significant differences in body weight only at the interval between calving and 10 days postpartum; this was the period when the greatest weight loss was registered.  The energy balance (expressed as percentage of requirements) ranged between 3 to 18 % at parturition and from -22 to -9 % for the rest of the sampling times. Regarding lipid profiles, cholesterol, LDL and HDL showed statistically significant differences; these values increased proportionally to time after parturition.  Triglycerides and VLDL, on the other hand, increased until 40 days and decrease at 50 days postpartum.  There were no significant difference for the number of follicles throughout the experimental period, and only six cows ovulated. The group of cows that ovulated was able to maintain positive conditions for the use of body reserves, expressed in a greater BCS at parturition time, and a higher blood-serum HDL concentrations; however, these cows presented the major weight loss, the earliest nadir of energy balance and the higher blood-serum cholesterol concentrations. This would result in a better energy balance that effectively expressed itself a shorter time from parturition to ovulation and more milk production.