Jeffrey L. Walck, Laila M. Karlsson, Per Milberg, Siti N. Hidayati, Tetsuya Kondo
Apr 18, 2012; 2012:7-7
Apr
18
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Seed germination and seedling development ecology in world-wide populations of a circumboreal Tertiary relict
Veselin Dimitrov Petrov, Frank Van Breusegem
Apr 18, 2012; 0:141-14
Invited review
Apr 18, 2012; 0:141-14
Invited review
Flowering is the most crucial act that plants undergo, as the fruits of such labor include crops on which the world depends, and seeds from which the next generation grows. While classic experiments have demonstrated that plants are able to adjust the timing of their flowering in response to environmental conditions, such as light and temperature, until now very little was known about what exactly triggers plants to make flowers instead of leaves. Now, a team of researchers from Singapore has discovered how this happens.
It provides the raw material for liquorice candy, calms the stomach and alleviates diseases of the airways: liquorice root. Chosen as the "Medicinal plant 2012," the root has been treasured in traditional healing since ancient times. Researchers have now discovered that liquorice root also contains substances with an anti-diabetic effect.
Apr
17
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Combined in silico/in vivo analysis of mechanisms providing for root apical meristem self-organization and maintenance
The root apical meristem (RAM) is the plant stem cell niche which provides for the formation and continuous development of the root. Auxin is the main regulator of RAM functioning, and auxin maxima coincide with the sites of RAM initiation and maintenance. Auxin gradients are formed due to local auxin biosynthesis and polar auxin transport. The PIN family of auxin transporters plays a critical role in polar auxin transport, and two mechanisms of auxin maximum formation in the RAM based on PIN-mediated auxin transport have been proposed to date: the reverse fountain and the reflected flow mechanisms.
The two mechanisms are combined here in in silico studies of auxin distribution in intact roots and roots cut into two pieces in the proximal meristem region. In parallel, corresponding experiments were performed in vivo using DR5::GFP Arabidopsis plants.
The reverse fountain and the reflected flow mechanism naturally cooperate for RAM patterning and maintenance in intact root. Regeneration of the RAM in decapitated roots is provided by the reflected flow mechanism. In the excised root tips local auxin biosynthesis either alone or in cooperation with the reverse fountain enables RAM maintenance.
The efficiency of a dual-mechanism model in guiding biological experiments on RAM regeneration and maintenance is demonstrated. The model also allows estimation of the concentrations of auxin and PINs in root cells during development and under various treatments. The dual-mechanism model proposed here can be a powerful tool for the study of several different aspects of auxin function in root.
Apr
16
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Evolutionary history of what mammals eat: Some groups of mammals have changed their feeding strategies over time
The feeding habits of mammals haven't always been what they are today, particularly for omnivores, finds a new study. Some groups of mammals almost exclusively eat meat -- take lions and tigers and other big cats. Other mammals such as deer, cows and antelope are predominantly plant-eaters, living on a diet of leaves, shoots and bark. But particularly for omnivores, the situation wasn't always that way, finds a new study.
Apr
16
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Chimpanzee ground nests offer new insight into our ancestors’ descent from the trees
The first study into rarely documented ground-nest building by wild chimpanzees offers new clues about the ancient transition of early hominins from sleeping in trees to sleeping on the ground. While most apes build nests in trees, this study focused on a group of wild West African chimpanzees that often shows ground-nesting behavior.
Mild mannered though they seem, plants are extremely competitive, especially when it comes to getting their fair share of sunlight. Whether a forest or a farm, where plants grow a battle wages for the sun's rays.
Have you ever wondered why stems grow upwards and roots downwards? Why plants always seem to turn towards the light and climbing plants run up the trellis rather than down?
Anthurium is an important horticultural crop from the family Araceae, order Alismatales, a lineage considered to have diverged from other monocots prior to the cereals. Genome size and its distribution in Anthurium were investigated to gain a basic understanding of genome organization in this large genus and to forge a firm foundation for advancement of molecular approaches for the study of Anthurium. Currently, genome size estimates have been reported for only two Anthurium samples.
Bulk nuclear DNA content estimates were obtained by flow cell cytometry using leaf tissue collected from Anthurium species of different subgeneric groups and from commercial cultivars. The most current and well-supported topology of subgeneric, sectional relationships was applied to present genome size estimates in the context of reported chromosome counts, karyotypes, putative phylogenetic relationships, observed phenotypes and pedigree.
Genome size estimates based on bulk nuclear DNA content for 77 accessions representing 34 species and 9 cultivars were obtained, including initial estimates for 33 Anthurium species, and both the smallest (Anthurium obtusum; Tetraspermium) and largest (Anthurium roseospadix; Calomystrium) Anthurium genome sizes reported to date. Genome size did not distinguish any subgeneric section, but ranged 5-fold (4.42–20.83 pg/2 C) despite consistent 2N= 30 chromosome counts. Intraspecies genome size variation >20 % is reported for Anthurium ravenii, A. watermaliense and A. gracile.
Genome size estimates for Anthurium species spanning 13 recognized subgeneric sections indicate that genome size does not generally correlate with chromosome count or phylogenetic relationships. Mechanisms of genome expansion and contraction, including amplification and reduction of repetitive elements, polyploidy, chromosome reorganization/loss, may be involved in genome evolution in Anthurium as in other species. The new information on Anthurium genome sizes provides a platform for molecular studies supporting further research on genome evolution as well as cultivar development.
Barbara J. Bliss, Jon Y. Suzuki
Apr 16, 2012; 2012:6-6
Apr 16, 2012; 2012:6-6
Apr
13
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Direct transfer of plant genes from chloroplasts into the cell nucleus: Gene function preserved despite structural differences in the DNA
Chloroplasts, the plant cell's green solar power generators, were once living beings in their own right. This changed about one billion years ago, when they were swallowed up but not digested by larger cells. Since then, they have lost much of their autonomy. As time went on, most of their genetic information found its way into the cell nucleus; today, chloroplasts would no longer be able to live outside their host cell. Scientists in Scientists have now discovered that chloroplast genes take a direct route to the cell nucleus, where they can be correctly read in spite of their architectural differences.
The once-mighty American chestnut tree, which was virtually wiped out by a pathogenic fungus that arrived in New York City more than 100 years ago, will return April 18 to the area where it was first discovered in the Bronx.
Personal Computer have changed the people life. And every person have a PC in their home in a normal family. And my opinion every one need a PC. But due the the huge amount of use of the energy due to the Computer in huge sector, the energy consumed is growing day by day. And there must be some solution to this problem. If the huge computer can be made to work in low power available then we can managed the energy saving and bring a revolution in the world.
A company has invented cheap pcs so that people can enjoy the low power consumption at low price. Its just not about the low price as power consumption directly effect you electricity bills and helps energy saving.
Its not just about the power consumption, but they are also the cheapest found on market. If people are really concious about the energy and the money then, I suggest people surely should get a one. I have order a piece for myself, as every good things should be started from ownself.
Save energy, Save world – Go green.
Apr
12
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Nutrient and toxin all at once: How plants absorb the perfect quantity of minerals
In order to survive, plants should take up neither too many nor too few minerals from the soil. New insights into how they operate this critical balance have now been determined. The researchers discovered novel functions of the metal-binding molecule nicotianamine.
Apr
12
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Round and large: morphological and genetic consequences of artificial selection on the gourd tree Crescentia cujete by the Maya of the Yucatan Peninsula, Mexico
Artificial selection, the main driving force of domestication, depends on human perception of intraspecific variation and operates through management practices that drive morphological and genetic divergences with respect to wild populations. This study analysed the recognition of varieties of Crescentia cujete by Maya people in relation to preferred plant characters and documents ongoing processes of artificial selection influencing differential chloroplast DNA haplotype distribution in sympatric wild and home-garden populations.
Fifty-three home gardens in seven villages (93 trees) and two putative wild populations (43 trees) were sampled. Through semi-structured interviews we documented the nomenclature of varieties, their distinctive characters, provenance, frequency and management. Phenotypic divergence of fruits was assessed with morphometric analyses. Genetic analyses were performed through five cpDNA microsatellites.
The Maya recognize two generic (wild/domesticated) and two specific domesticated (white/green) varieties of Crescentia cujete. In home gardens, most trees (68 %) were from domesticated varieties while some wild individuals (32 %) were tolerated. Cultivation involves mainly vegetative propagation (76 %). Domesticated fruits were significantly rounder, larger and with thicker pericarp than wild fruits. Haplotype A was dominant in home gardens (76 %) but absent in wild populations. Haplotypes B–F were found common in the wild but at low frequency (24 %) in home gardens.
The gourd tree is managed through clonal and sexual propagules, fruit form and size being the main targets of artificial selection. Domesticated varieties belong to a lineage preserved by vegetative propagation but propagation by seeds and tolerance of spontaneous trees favour gene flow from wild populations. Five mutational steps between haplotypes A and D suggest that domesticated germplasm has been introduced to the region. The close relationship between Maya nomenclature and artificial selection has maintained the morphological and haplotypic identity (probably for centuries) of domesticated Crescentia despite gene flow from wild populations.
Apr
12
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Floral development of Hydrocera and Impatiens reveals evolutionary trends in the most early diverged lineages of the Balsaminaceae
Balsaminaceae consist of two genera, the monospecific Hydrocera and its species-rich sister Impatiens. Although both genera are seemingly rather similar in overall appearance, they differ in ecology, distribution range, habitat preference and morphology. Because morphological support for the current molecular phylogenetic hypothesis of Impatiens is low, a developmental study is necessary in order to obtain better insights into the evolutionary history of the family. Therefore, the floral development of H. triflora and I. omeiana was investigated, representing the most early-diverged lineage of Impatiens, and the observations were compared with the literature.
Flowers at all developmental stages were examined using scanning electron microscopy and light microscopy.
In Hydrocera, two whorls of five free perianth primordia develop into a less zygomorphic perianth compared with its sister genus. The androecial cap originates from five individual stamen primordia. Post-genital fusion of the upper parts of the filaments result in a filament ring below the anthers. The anthers fuse forming connivent anther-like units. The gynoecium of Hydrocera is pentamerous; it is largely synascidiate in early development. Only then is a symplicate zone formed resulting in style and stigmas. In I. omeiana, the perianth is formed as in Hydrocera. Five individual stamen primordia develop into five stamens, of which the upper part of the filaments converge with each other. The gynoecium of I. omeiana is tetramerous; it appears annular in early development.
Comparison of the present results with developmental data from the literature confirms the perianth morphocline hypothesis in which a congenital fusion of the parts of the perianth results in a shift from pentasepalous to trisepalous flowers. In addition, the development of the androecial cap and the gynoecium follows several distinct ontogenetic sequences within the family.
Apr
12
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Wait or escape? Contrasting submergence tolerance strategies of Rorippa amphibia, Rorippa sylvestris and their hybrid
Differential responses of closely related species to submergence can provide insight into the evolution and mechanisms of submergence tolerance. Several traits of two wetland species from habitats with contrasting flooding regimes, Rorippa amphibia and Rorippa sylvestris, as well as F1 hybrid Rorippa x anceps were analysed to unravel mechanisms underlying submergence tolerance.
In the first submergence experiment (lasting 20 d) we analysed biomass, stem elongation and carbohydrate content. In the second submergence experiment (lasting 3 months) we analysed survival and the effect of re-establishment of air contact on biomass and carbohydrate content. In a separate experiment we analysed expression of two carbohydrate catabolism genes, ADH1 and SUS1, upon re-establishment of air contact following submergence.
All plants had low mortality even after 3 months of submergence. Rorippa sylvestris was characterized by 100 % survival and higher carbohydrate levels coupled with lower ADH1 gene expression as well as reduced growth compared with R. amphibia. Rorippa amphibia and the hybrid elongated their stems but this did not pay-off in higher survival when plants remained submerged. Only R. amphibia and the hybrid benefited in terms of increased biomass and carbohydrate accumulation upon re-establishing air contact.
Results demonstrate contrasting ‘escape’ and ‘quiescence’ strategies between Rorippa species. Being a close relative of arabidopsis, Rorippa is an excellent model for future studies on the molecular mechanism(s) controlling these strategies.
The effect of environmental factors on the regulation of aerenchyma formation in rice roots has been discussed for a long time, because aerenchyma is constitutively formed under aerated conditions. To elucidate this problem, a unique method has been developed that enables sensitive detection of differences in the development of aerenchyma under two different environmental conditions. The method is tested to determine whether aerenchyma development in rice roots is affected by osmotic stress.
To examine aerenchyma formation both with and without mannitol treatment in the same root, germinating rice (Oryza sativa) caryopses were sandwiched between two agar slabs, one of which contained 270 m
Structural continuity of aerenchyma was clearly visualized in 3-D in the primary root of rice and in situ using X-ray CT. Light microscopy and X-ray CT showed that the development of aerenchyma was promoted on the mannitol-treated side of the root. Detailed light microscopic analysis of cross-sections cut along the root axis from the tip to the basal region demonstrated that aerenchyma developed significantly closer to the root tip on the mannitol-treated side of the root.
Continuity of the aerenchyma along the rice root axis was morphologically demonstrated using X-ray CT. By using this ‘sandwich’ method it was shown that mannitol promoted aerenchyma formation in the primary roots of rice.
Seed size is controlled by small RNA molecules inherited from a plant's mother, a discovery that has implications for agriculture and understanding plant evolution.
Apr
11
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Tackle fungal forces to save crops, forests and endangered animals, say scientists
More than 600 million people could be fed each year by halting the spread of fungal diseases in the world's five most important crops, according to new research.
Global warming may initially make the grass greener, but not for long, according to new research results. The findings show that plants may thrive in the early stages of a warming environment but then begin to deteriorate quickly.
Climate change is projected to have far-reaching environmental impacts both domestically and abroad. A recently published report examines the impact of climate change on forest diseases and how these pathogens will ultimately affect forest ecosystems in the Western United States and Canada.