Can seed production and restricted dispersal limit recruitment in Pinus pinaster Aiton from the Spanish Northern Plateau?

Natural regeneration faces increasing difficulties in dry forests from the Mediterranean basin, including for normally well-regenerating species such as maritime pine (Pinus pinaster Aiton). In this paper, we studied female fertility, seed dispersal and spread rates in P. pinaster from the Spanish Northern Plateau, where natural regeneration failure is a main concern for forest managers. For this purpose we periodically collected data from seed traps and trees located at two core locations across several years. We found significant variation in interannual cone production, with the best seed trees being the same across years. In addition, we found highly skewed distributions of female reproductive effort and large fertility differences across stands located few kilometres away. Annual seed dispersal kernels fitted lognormal or 2Dt models depending on the stand analysed, with median dispersal distances between 14 and 25 m. Kernels fitted for maximum dispersal periods showed an outstanding intraseasonal variation of median dispersal distances, from 10 to 54 m, in association to variable patterns of rainfall and maximum wind speed. The amount of seed produced appeared to be enough to guarantee the natural regeneration of the stands during the typical 20-year regeneration period. Colonisation simulations concluded that Mediterranean maritime pine has a notable dispersion capacity, which is strongly influenced by levels of fecundity and, especially, by the number and frequency of long-distance dispersal events. The latter play a key role in tree dispersion processes through enlarging the occupied area and fostering the invasion of abandoned crop land.

bZIP transcription factors in the regulatory networks controlling seed maturation and germination of Arabidopsis thaliana

Se describe la expresión por RTqPCR de los genes que codifican los factores transcripcionales bZIP44 y bZIP9. Asimismo se establece la interacción entre ambas proteínas en el sistema de 2 híbridos de levadura y in planta por complementación bimolecular fluorescente.

Combinatorial interaction between AtbZIP44 and other bZIP transcription factors in the regulation of Arabidopsis thaliana seed maturation and germination

El gen AtbZIP44 se expresa en el endospermo micropilar y en la radícula de semillas en germinación. El mRNA del gen AtbZIP9 se localiza también en la radícula. Se realizan experimentos de interacción proteína-proteína entre los correspondientes factores transcripcionales.

A partial study of vertical distribution of conventional no-till seeders and spatial variability of seed depth placement of maize in the Alentejo region, Portugal

The requirements for a good stand in a no-till field are the same as those for conventional planting as well as added field and machinery management. Among the various factors that contribute towards producing a successful maize crop, seed depth placement is a key determinant. Although most no-till planters on the market work well under good soil and residue conditions, adjustments and even modifications are frequently needed when working with compacted or wet soils or with heavy residues. The main objective of this study, carried out in 2010, 2011 and 2012, was to evaluate the vertical distribution and spatial variability of seed depth placement in a maize crop under no-till conditions, using precision farming technologies and conventional no-till seeders. The results obtained indicate that the seed depth placement was affected by soil moisture content and forward speed. The seed depth placement was negatively correlated with soil resistance and seeding depth had a significant impact on mean emergence time and the percentage of emerged plants. Shallow average depth values and high coefficients of variation suggest a need for improvements in controlling the seeders’ sowing depth mechanism or more accurate calibration by operators in the field.

Spatial variability of seed depth placement of maize under no tillage in Alentejo, Portugal

Among the various factors that contribute towards producing a successful maize crop, seed depth placement is a key determinant, especially in a no-tillage system. The main objective of this work was to evaluate the spatial variability of seed depth placement and crop establishment in a maize crop under no-tillage conditions, using precision farming technologies. The obtained results indicate that seed depth placement was significantly affected by soil moisture content, while a very high coefficient of variation of 39% was found for seed depth. Seeding depth had a significant impact on mean emergence time and percentage of emerged plants. Shallow average depth values and the high coefficient of variation suggest a need for improvement in controlling the seeders sowing depth.

Contribute to the Study of Vertical Distribution of Conventional No-Till Seeders and Spatial Variability of Seed Depth Placement of Maize in Alentejo, Portugal

Entre os vários fatores que contribuem para a produção de uma cultura de milho, a distribuição vertical dos semeadores avaliada através da localização da semente em profundidade é um fator-chave, especialmente na técnica de sementeira direta. Simultaneamente, dada a complexidade dos ecossistemas naturais e agrícolas em sistemas de agricultura de conservação, a gestão diferenciada e localizada das parcelas assume um importante papel na análise e gestão da variabilidade das propriedades do solo e estabelecimento das culturas, nomeadamente utilizando informação geo referenciada e tecnologia expedita. Assim, o principal objetivo desta Tese foi a avaliação em culturas de milho da variabilidade espacial da localização de semente em profundidade e estabelecimento da cultura em sementeira direta usando sistemas convencionais de controlo de profundidade, tendo-se comparado com diferentes sistemas de mobilização e recorrendo a tecnologias de agricultura de precisão. Os ensaios decorreram na região Mediterrânea do Alentejo, em propriedades agrícolas no decorrer das campanhas de 2010, 2011, 2012 e 2015 em 6 diferentes campos experimentais. O trabalho experimental consistiu em ensaios com avaliações in loco do solo e cultura, consumo de combustível das operações e deteção remota. Os resultados obtidos indicam que não só o sistema de mobilização afetou a localização da semente em profundidade, como em sementeira direta a profundidade de sementeira foi afetada pelo teor de humidade do solo, resistência do solo à profundidade e velocidade da operação de sementeira. Adicionalmente observaram-se condições heterogéneas de emergência e estabelecimento da cultura afetadas por condições físicas de compactação do solo. Comparando os diferentes sistemas de mobilização, obteve-se uma significativa redução de combustível para a técnica de sementeira direta, apesar de se terem observado diferenças estatísticas significativas considerando diferentes calibrações de profundidade de sementeira Do trabalho realizado nesta Tese ressalva-se a importância que as tecnologias de agricultura de precisão podem ter no acompanhamento e avaliação de culturas em sementeira direta, bem como a necessidade de melhores procedimentos no controlo de profundidade dos semeadores pelo respetivos operadores ou ao invés, a adoção de semeadores com mecanismos ativos de controlo de profundidade. ABSTRACT Among the various factors that contribute towards producing a successful maize crop, seeders vertical distribution evaluated through seed depth placement is a key determinant, especially under a no-tillage technique. At the same time in conservation agriculture systems due to the complexity of natural and agricultural ecosystems site specific management became an important approach to understand and manage the variability of soil properties and crop establishment, especially when using geo spatial information and affording readily technology Thus, the main objective of this Thesis was to evaluate the spatial variability of seed depth placement and crop establishment in maize crops under no-tillage conditions compared to different tillage systems, using conventional seed depth control no till seeders and precision farming technologies. Trials were carried out in the Mediterranean region of Alentejo, in private farms along the sowing operations season over the years 2010, 2011, 2012 and 2015 in 6 different experimental fields. Experimental work covered field tests with in loco soil and crop evaluations, fuel operation evaluations and aerial sensing. The results obtained indicate that not only tillage system affected seed depth placement but under no till conditions seed depth was affected by soil moisture content, soil resistance to penetration and seeders forward speed. In addition uneven crop seedling and establishment depended on seed depth placement and could be affected by physical problems of compaction layers. Significant reduction in fuel consumption was observed for no till operations although significant differences observed according to different setting calibrations of seed depth control. According to the results, precision agriculture is an important tool to evaluate crops under no till conditions and seed depth mechanisms should be more accurate by the operators or is determinant the adoption of new active depth control technology to improve seeders performance.

Seed germination characteristics of Phillyrea angustifolia L. and P. latifolia L. (Oleaceae), two Mediterranean shrub species having lignified endocarp

The aim of this study was to determine the germination characteristics of Phillyrea angustifolia L. and P. latifolia L. seeds in order to develop an optimized propagation protocol for Phillyrea species. Seeds of P. angustifolia and P. latifolia were collected from wild plants growing in Cáceres province (CW Spain) and Andalucía (S Spain), respectively. Percentage of water uptake for P. latifolia seeds was calculated. Seeds with and without endocarp were germinated at different constant and alternating temperatures. Seeds without endocarp were soaked in distilled water or gibberellic acid, and then set to germinate. Seeds with endocarp of both species were stratified at 5 ºC for 30 or 90 days and then the endocarp was completely removed from the seeds before they were sowed. Chemical scarification with sulfuric acid and mechanical scarification were tested on P. angustifolia seeds with endocarp. Phillyrea endocarp was permeable to water, since Phillyrea seeds with endocarp imbibed water, but water uptake was faster when the endocarp was removed. Moreover, the encodarp could interfere mechanically in the emergence of the radicle, since seed germination of Phillyrea species was promoted by the complete removal of the lignified endocarp surrounding each seed. Optimal germination temperature for both species was 15 ºC, and lower temperatures produced secondary dormancy. Soaking in distilled water or gibberellic acid did not significantly enhance seed germination. Cold stratification and chemical scarification treatments were detrimental for seed germination. Keywords cold stratification, Phillyrea species, treatments before sowing, seed germination, seed scarification, lignified endocarp.

Mannans and endo-beta-mannanases (MAN) in Brachypodium distachyon: expression profiling and possible role of the BdMAN genes during coleorhiza-limited seed germination

Immunolocalization of mannans in the seeds of Brachypodium distachyon reveals the presence of these polysaccharides in the root embryo and in the coleorhiza in the early stages of germination (12h), decreasing thereafter to the point of being hardly detected at 27h. Concurrently, the activity of endo-β-mannanases (MANs; EC 3.2.1.78) that catalyse the hydrolysis of β-1,4 bonds in mannan polymers, increases as germination progresses. The MAN gene family is represented by six members in the Brachypodium genome, and their expression has been explored in different organs and especially in germinating seeds. Transcripts of BdMAN2, BdMAN4 and BdMAN6 accumulate in embryos, with a maximum at 24–30h, and are detected in the coleorhiza and in the root by in situ hybridization analyses, before root protrusion (germination sensu stricto). BdMAN4 is not only present in the embryo root and coleorhiza, but is abundant in the de-embryonated (endosperm) imbibed seeds, while BdMAN2 and BdMAN6 are faintly expressed in endosperm during post-germination (36–42h). BdMAN4 and BdMAN6 transcripts are detected in the aleurone layer. These data indicate that BdMAN2, BdMAN4 and BdMAN6 are important for germination sensu stricto and that BdMAN4 and BdMAN6 may also influence reserve mobilization. Whether the coleorhiza in monocots and the micropylar endosperm in eudicots have similar functions, is discussed.

Enhanced methionine levels and increased nutritive value of seeds of transgenic lupins (Lupinus angustifolius L.) expressing a sunflower seed albumin gene

With the aim of improving the nutritive value of an important grain legume crop, a chimeric gene specifying seed-specific expression of a sulfur-rich, sunflower seed albumin was stably transformed into narrow-leafed lupin (Lupinus angustifolius L.). Sunflower seed albumin accounted for 5% of extractable seed protein in a line containing a single tandem insertion of the transferred DNA. The transgenic seeds contained less sulfate and more total amino acid sulfur than the nontransgenic parent line. This was associated with a 94% increase in methionine content and a 12% reduction in cysteine content. There was no statistically significant change in other amino acids or in total nitrogen or total sulfur contents of the seeds. In feeding trials with rats, the transgenic seeds gave statistically significant increases in live weight gain, true protein digestibility, biological value, and net protein utilization, compared with wild-type seeds. These findings demonstrate the feasibility of using genetic engineering to improve the nutritive value of grain crops.

Directed seed dispersal by bellbirds in a tropical cloud forest

A fundamental goal of plant population ecology is to understand the consequences for plant fitness of seed dispersal by animals. Theories of seed dispersal and tropical forest regeneration suggest that the advantages of seed dispersal for most plants are escape from seed predation near the parent tree and colonization of vacant sites, the locations of which are unpredictable in space and time. Some plants may gain in fitness as a fortuitous consequence of disperser behavior if certain species of dispersers nonrandomly place seeds in sites predictably favorable for seedling establishment. Such patterns of directed dispersal by vertebrates long have been suggested but never demonstrated for tropical forest trees. Here we report the pattern of seed distribution and 1-year seedling survival generated by five species of birds for a neotropical, shade-tolerant tree. Four of the species dispersed seeds to sites near the parent trees with microhabitat characteristics similar to those at random locations, whereas the fifth species, a bellbird, predictably dispersed seeds under song perches in canopy gaps. The pattern of seedling recruitment was bimodal, with a peak near parent trees and a second peak, corresponding to bellbird song perches, far (>40 m) from parent trees. Seedling survival was higher for seeds dispersed by bellbirds than by the other species, because of a reduction in seedling mortality by fungal pathogens in gaps. Thus, bellbirds play a significant role in seed dispersal by providing directed dispersal to favorable sites and therefore may influence plant recruitment patterns and species diversity in Neotropical forests.

Are the pneumococcal polysaccharide vaccines effective? Meta-analysis of the prospective trials

The objective was to review the evidence of effectiveness of the polyvalent polysaccharide pneumococcal vaccine from prospective properly randomised controlled trials comparing pneumococcal vaccines with placebo in subjects who are immunocompetent and those likely to have an impaired immune system.

Cloning and Characterization of TPE4A, a Thiol-Protease Gene Induced during Ovary Senescence and Seed Germination in Pea1

A cDNA clone encoding a thiol-protease (TPE4A) was isolated from senescent ovaries of pea (Pisum sativum) by reverse transcriptase-polymerase chain reaction. The deduced amino acid sequence of TPE4A has the conserved catalytic amino acids of papain. It is very similar to VSCYSPROA, a thiol-protease induced during seed germination in common vetch. TPE4A mRNA levels increase during the senescence of unpollinated pea ovaries and are totally suppressed by treatment with gibberellic acid. In situ hybridization indicated that TPE4A mRNA distribution in senescent pea ovaries is different from that of previously reported thiol-proteases induced during senescence, suggesting the involvement of different proteases in the mobilization of proteins from senescent pea ovaries. TPE4A is also induced during the germination of pea seeds, indicating that a single protease gene can be induced during two different physiological processes, senescence and germination, both of which require protein mobilization.

Temporal and Spatial Patterns of Accumulation of the Transcript of Myo-Inositol-1-Phosphate Synthase and Phytin-Containing Particles during Seed Development in Rice1

Myo-inositol-1-phosphate (I[1]P) synthase (EC 5.5.1.4) catalyzes the reaction from glucose 6-phosphate to I(1)P, the first step of myo-inositol biosynthesis. Among the metabolites of I(1)P is inositol hexakisphosphate, which forms a mixed salt called phytin or phytate, a storage form of phosphate and cations in seeds. We have isolated a rice (Oryza sativa L.) cDNA clone, pRINO1, that is highly homologous to the I(1)P synthase from yeast and plants. Northern analysis of total RNA showed that the transcript accumulated to high levels in embryos but was undetectable in shoots, roots, and flowers. In situ hybridization of developing seeds showed that the transcript first appeared in the apical region of globular-stage embryos 2 d after anthesis (DAA). Strong signals were detected in the scutellum and aleurone layer after 4 DAA. The level of the transcript in these cells increased until 7 DAA, after which time it gradually decreased. Phytin-containing particles called globoids appeared 4 DAA in the scutellum and aleurone layer, coinciding with the localization of the RINO1 transcript. The temporal and spatial patterns of accumulation of the RINO1 transcript and globoids suggest that I(1)P synthase directs phytin biosynthesis in rice seeds.

Age-Induced Protein Modifications and Increased Proteolysis in Potato Seed-Tubers1

Long-term aging of potato (Solanum tuberosum) seed-tubers resulted in a loss of patatin (40 kD) and a cysteine-proteinase inhibitor, potato multicystatin (PMC), as well as an increase in the activities of 84-, 95-, and 125-kD proteinases. Highly active, additional proteinases (75, 90, and 100 kD) appeared in the oldest tubers. Over 90% of the total proteolytic activity in aged tubers was sensitive to trans-epoxysuccinyl-l-leucylamido (4-guanidino) butane or leupeptin, whereas pepstatin was the most effective inhibitor of proteinases in young tubers. Proteinases in aged tubers were also inhibited by crude extracts or purified PMC from young tubers, suggesting that the loss of PMC was responsible for the age-induced increase in proteinase activity. Nonenzymatic oxidation, glycation, and deamidation of proteins were enhanced by aging. Aged tubers developed “daughter” tubers that contained 3-fold more protein than “mother” tubers, with a polypeptide profile consistent with that of young tubers. Although PMC and patatin were absent from the older mother tubers, both proteins were expressed in the daughter tubers, indicating that aging did not compromise the efficacy of genes encoding PMC and patatin. Unlike the mother tubers, proteinase activity in daughter tubers was undetectable. Our results indicate that tuber aging nonenzymatically modifies proteins, which enhances their susceptibility to breakdown; we also identify a role for PMC in regulating protein turnover in potato tubers.

A Fiberless Seed Mutation in Cotton Is Associated with Lack of Fiber Cell Initiation in Ovule Epidermis and Alterations in Sucrose Synthase Expression and Carbon Partitioning in Developing Seeds1

Fiber cell initiation in the epidermal cells of cotton (Gossypium hirsutum L.) ovules represents a unique example of trichome development in higher plants. Little is known about the molecular and metabolic mechanisms controlling this process. Here we report a comparative analysis of a fiberless seed (fls) mutant (lacking fibers) and a normal (FLS) mutant to better understand the initial cytological events in fiber development and to analyze the metabolic changes that are associated with the loss of a major sink for sucrose during cellulose biosynthesis in the mutant seeds. On the day of anthesis (0 DAA), the mutant ovular epidermal cells lacked the typical bud-like projections that are seen in FLS ovules and are required for commitment to the fiber development pathway. Cell-specific gene expression analyses at 0 DAA showed that sucrose synthase (SuSy) RNA and protein were undetectable in fls ovules but were in abundant, steady-state levels in initiating fiber cells of the FLS ovules. Tissue-level analyses of developing seeds 15 to 35 DAA revealed an altered temporal pattern of SuSy expression in the mutant relative to the normal genotype. Whether the altered programming of SuSy expression is the cause or the result of the mutation is unknown. The developing seeds of the fls mutant have also shown several correlated changes that represent altered carbon partitioning in seed coats and cotyledons as compared with the FLS genotype.