Higher Plant Species Research Articles

PhytOC in plant ecological system and its important roles in the global soil carbon sink.

As a substantial component of soil organic carbon occluded within phytoliths，PhytOC is a result of biomineralization within plants and highly resistant to decomposition in the soil environment. PhytOC accumulation rates have contributed about 15.0%-37.0% to the estimated global mean long-term soil carbon accumulation rate which is 2.4 gm-2a-1 over the last 10 000 years. There are ways to enhance both short and long-term carbon sequestration by cultivation of high PhytOC-yielding plant species of agricultural crops. Most of the economically important agricultural plant species such as barley，maize，rice，sorghum，sugarcane and wheat, are producers of phytoliths. It was estimated that the above-mentioned crops globally produced PhytOC of （5.08-12.01）106 ta-1. The paper reviewed the formation mechanism，characteristics and accumulation rate of PhytOC in the plant ecological system，the agronomy measures to improve the accumulation rate and its important role in the global soil carbon sink. ［Ch，56 ref.］

Topography and edge effects are more important than elevation as drivers of vegetation patterns in a neotropical montane forest

AbstractAimsThe high plant species diversity of tropical mountain forests is coupled with high habitat heterogeneity along gradients in elevation and topography. We quantified the effects of elevation, topography and forest edge on habitat conditions and woody plant diversity of tropical montane forest fragments.LocationTropical montane forest fragments, ‘Yungas’, Bolivia.MethodsWe measured microclimate and sampled soil properties and woody vegetation at forest edges and in the forest interior on ridges and in gorges along an elevational gradient of 600 m. We analysed effects of elevation, topography and forest edge on habitat conditions (i.e. microclimate, soil properties and forest structure), species richness, evenness and composition with linear mixed effects models and detrended correspondence analysis (DCA).ResultsChanges in habitat conditions were weaker along the elevational gradient than between forest interior and forest edge and between different topographies. Species richness was not affected by any gradient, while species evenness was reduced at forest edges. All three gradients affected species composition, while effects of topography and forest edge were stronger than that of elevation.ConclusionsIn general, effects of the 600‐m elevational gradient were weak compared to effects of forest edge and topography. Edge effects shifted species composition towards pioneer species, while topographical heterogeneity is particularly important for generating high diversity in montane forests. These results underscore that edge effects have severe consequences in montane forest remnants and that small‐scale variation between topographical microhabitats should be considered in studies that predict monotonous upslope migrations of plant species in tropical montane forests due to global warming.

Function of small habitat elements for enhancing plant diversity in different agricultural landscapes

The extensive transformation of agricultural landscapes worldwide has led to a decrease in grassland species related to traditional low-intensive farming. To properly manage and protect species, habitats and ecosystems in any of these landscapes requires a better understanding of direct and indirect effects of the processes driving biodiversity decline. In this study, we investigated how small habitat elements, represented by mid-field islets and road verges, in different types of agricultural landscapes can sustain a regional species pool for plant diversity otherwise associated to semi-natural grasslands. Although semi-natural grasslands had higher total and specialist richness, we found that small habitat elements harboured relatively high plant species richness, especially in a landscape with many semi-natural grasslands left. In the most intensively managed landscape, total richness declined as distance to the nearest semi-natural grassland increased. In contrast, β-diversity was highest in these landscapes indicating that small habitats are also negatively affected by distance to grassland. We found that species trait composition varied depending on habitat and landscape. The results confirm that fragmentation shape trait composition within plant communities, e.g. plant size, clonality, longevity, and dispersal traits. We conclude that small habitat elements increase the total area available to grassland species present in the landscape, boosting the spatio-temporal dynamics of grassland communities. Small habitat elements may hence function as refugia or stepping stone habitats, especially in intensively utilized agricultural landscapes, and should be regarded as a functional part of a semi-natural grassland network, analogous to a meta-population.

Genetic diversity among clumps of Acanthorrhynchium papillatum (Harv.) M.Fleisch. as measured by variation in ITS2 sequences

Population genetic variation in the tropical moss species Acanthorrhynchium papillatum was evaluated using nucleotide sequences of the second Internal Transcribed Spacer (ITS2) region of the nuclear ribosomal DNA. High levels of variation were observed at both nucleotide and haplotype levels using this marker, indicating that the various populations in southern Peninsular Malaysia and Singapore have been genetically isolated to a large extent over time despite short spatial distances between some of the populations. Sequence analysis suggests that ITS2 diversity arises from high rates of mutation at this locus. In common with earlier results from microsatellite marker analysis, these results demonstrate that the genetic diversity of mosses may be high, as with higher plant species. Overall, relatively lower levels of diversity were seen in ITS2 loci compared to microsatellite markers. Thus the ITS2 region can be a useful additional DNA marker for analysing genetic diversity in this moss species.

수변 복원 시 식물종 다양성 증진을 위한 β-diversity 연구

식물종 다양성이 높은 하천변 복원을 위해 8개 하천 13지점에서 자연하천변 식물군락의 이질성을 <TEX>${\beta}$</TEX>-diversity로 조사하였다. 그 결과, 하천에서 내륙으로 들어감에 따른 이질성의 평균값은 0.32이었다(0.23~0.37범위). 이 값은 식물군락의 종 구성이 6번 완전히 바뀌는 community turnover를 나타낸다. <TEX>${\beta}$</TEX>-diversity는 섬진강, 한강, 낙동강, 금강 수계 간에 차이가 없었고, 각 수계 안에서 하천 유역은 하류(0.23)보다 상류(0.36)에서 더 높았다(p level<0.05). 환경요인과의 관계를 알아보기 위해 다중회귀분석을 실시한 결과 <TEX>${\beta}$</TEX>-diversity는 경사도에서 유의성이 나타났다. Belt-transect를 통해 나타난 종들과 <TEX>${\beta}$</TEX>-diversity 값을 통해 하천변의 우점종 모식도를 그려보면 상류의 종조성은 6번 바뀌고, 하류의 종조성은 약 5번 바뀌었다. 본 연구 결과를 통해 하천 계획에 실질적으로 활용할 수 있는 식재 수종과 식재 패턴의 기초를 제시하였으며, 하천변 식물군락의 종 다양성을 높이기 위해서는 경사도를 높이는 것이 가장 중요하다. We have researched heterogeneity of naturalized river plant community by <TEX>${\beta}$</TEX>-diversity for restoration of river community which has high diversity plant species. As a result the average of heterogeneity was 0.32(range 0.23~0.37) from the river to the inland. This value shows community turnover of species composition of plant communities 6 times. The <TEX>${\beta}$</TEX>-diversity was no difference among water system of Seomjin river, Han river, Nakdong river and Geum river. The upper-river valley(0.36) was higher than lower-river valley(0.23) in each water system(p level<0.05). Multiple regressing analysis was used for look the relationship with Environmental factors as a result, it shows <TEX>${\beta}$</TEX>-diversity significant on a slope. River mimetic diagram with dominant species that appear through Belt-transect painted. Dominant plant species turned 6 time in upper-river and turned about 5 time in lower-river. The result of this study suggested practical basis of planting species and planting pattern. To improve species diversity of river plant community, slope degree raise is the most important.

Insights from the Complete Chloroplast Genome into the Evolution of Sesamum indicum L

Sesame (Sesamum indicum L.) is one of the oldest oilseed crops. In order to investigate the evolutionary characters according to the Sesame Genome Project, apart from sequencing its nuclear genome, we sequenced the complete chloroplast genome of S. indicum cv. Yuzhi 11 (white seeded) using Illumina and 454 sequencing. Comparisons of chloroplast genomes between S. indicum and the 18 other higher plants were then analyzed. The chloroplast genome of cv. Yuzhi 11 contains 153,338 bp and a total of 114 unique genes (KC569603). The number of chloroplast genes in sesame is the same as that in Nicotiana tabacum, Vitis vinifera and Platanus occidentalis. The variation in the length of the large single-copy (LSC) regions and inverted repeats (IR) in sesame compared to 18 other higher plant species was the main contributor to size variation in the cp genome in these species. The 77 functional chloroplast genes, except for ycf1 and ycf2, were highly conserved. The deletion of the cp ycf1 gene sequence in cp genomes may be due either to its transfer to the nuclear genome, as has occurred in sesame, or direct deletion, as has occurred in Panax ginseng and Cucumis sativus. The sesame ycf2 gene is only 5,721 bp in length and has lost about 1,179 bp. Nucleotides 1–585 of ycf2 when queried in BLAST had hits in the sesame draft genome. Five repeats (R10, R12, R13, R14 and R17) were unique to the sesame chloroplast genome. We also found that IR contraction/expansion in the cp genome alters its rate of evolution. Chloroplast genes and repeats display the signature of convergent evolution in sesame and other species. These findings provide a foundation for further investigation of cp genome evolution in Sesamum and other higher plants.

Improvement of Polyunsaturated Fatty Acid Production in Echium acanthocarpum Transformed Hairy Root Cultures by Application of Different Abiotic Stress Conditions.

Fatty acids are of great nutritional, therapeutic, and physiological importance, especially the polyunsaturated n-3 fatty acids, possessing larger carbon chains and abundant double bonds or their immediate precursors. A few higher plant species are able to accumulate these compounds, like those belonging to the Echium genus. Here, the novel E. acanthocarpum hairy root system, which is able to accumulate many fatty acids, including stearidonic and α-linolenic acids, was optimized for a better production. The application of abiotic stress resulted in larger yields of stearidonic and α-linolenic acids, 60 and 35%, respectively, with a decrease in linoleic acid, when grown in a nutrient medium consisting of B5 basal salts, sucrose or glucose, and, more importantly, at a temperature of 15°C. The application of osmotic stress employing sorbitol showed no positive influence on the fatty acid yields; furthermore, the combination of a lower culture temperature and glucose did not show a cumulative boosting effect on the yield, although this carbon source was similarly attractive. The abiotic stress also influenced the lipid profile of the cultures, significantly increasing the phosphatidylglycerol fraction but not the total lipid neither their biomass, proving the appropriateness of applying various abiotic stress in this culture to achieve larger yields.

In silico analysis of dicer-like protein (DCLs) sequences from higher plant species

Dicer and Dicer like (DCLs) proteins are essential part of small RNA biogenesis pathway, is a type of RNase III digesting long dsRNA (pre-miRNA) to small RNA segments (miRNA). A total of 20 full length of Dicer like proteins (DCL1, DCL2, DCL3 and DCL4) from different organisms available in NCBI were evaluated by bioinformatics tools to investigate properties, structure of DCLs, domain analysis, multiple sequence alignment and phylogenetics tree construction. All DCLs protein sequences have Ribonuclease III protein family that contains RNaseIII domain including Helicase ATP-binding type-1, Helicase C-terminal, Dicer double-stranded RNA-binding fold, PAZ, Ribonuclease III, Double stranded RNA-binding domain (dsRB). Physicochemical analysis offers data such as pI, EC, Al, GRAVY and instability index about these enzymes. Putative phosphorylation sites were also identified which are found to be conserved in plant species and the results showed that the most abundant phosphorylation site is Serine residues in DCLs proteins. Patterns and profile analysis were performed using Prosite and conserved protein motifs subjected to MEME to obtain the best possible matches. The phylogenetics tree represented three major clusters and similar DCLs protein sequences of different plant species clustered together. The obtained results could be used for further in silico analysis and homology modeling studies. Keywords: Dicer, DCLs, miRNA, RNase, In silico analysis. *Corresponding Author: Ertugrul Filiz (e-mail: ertugrulfiliz@gmail.com). (Received: 25.05.2012 Accepted: 24.01.2013)

Molecular cloning and expression analysis of a gene for sucrose transporter from pear (Pyrus bretschneideri Rehd.) fruit

Here we report the cloning of a sucrose transporter cDNA from pear (Pyrus bretschneideri Rehd. cv ‘Yali’) fruit and an analysis of the expression of the gene. A cDNA clone, designated PbSUT1 was identified as a sucrose transporter cDNA from its sequence homology at the amino acid level to sucrose transporters that have been cloned from other higher plant species. PbSUT1 potentially encoded a protein of 499 amino acid residues with a predicted molecular mass of 53.4 kDa and an isoelectric point (pI) of 9.21. Phylogenetic analysis revealed that the PbSUT1 belonged to type III SUTs and was more closely related to the MdSUT1 from apple fruit. Some major facilitator superfamily (MFS)-specific sequence motifs were found in the predicted PbSUT1 peptides, and an MFS_1 domain was located at the amino acid positions of 29–447 of the sequence. A study of gene expression along fruit development showed that PbSUT1 transcripts are present at all stages but significantly increase before fruit enlargement and during the ripening process with increasing sucrose levels. In contrast, the expression levels don't change much during the period of rapid fruit growth. This work shows that sucrose transporter may play a role in the accumulation of sugars during maturation and in maintaining the internal cellular distribution.

Precipitation of the warmest quarter and temperature of the warmest month are key to understanding the effect of climate change on plant species diversity in Southern African savannah

AbstractIn this study, we test for the key bioclimatic variables that significantly explain the current distribution of plant species richness in a southern African ecosystem as a preamble to predicting plant species richness under a changed climate. We used 54,000 records of georeferenced plant species data to calculate species richness and spatially interpolated climate data to derive nineteen bioclimatic variables. Next, we determined the key bioclimatic variables explaining variation in species richness across Zimbabwe using regression analysis. Our results show that two bioclimatic variables, that is, precipitation of the warmest quarter (R2 = 0.92, P &lt; 0.001) and temperature of the warmest month (R2 = 0.67, P &lt; 0.001) significantly explain variation in plant species richness. In addition, results of bioclimatic modelling using future climate change projections show a reduction in the current bio‐climatically suitable area that supports high plant species richness. However, in high‐altitude areas, plant richness is less sensitive to climate change while low‐altitude areas show high sensitivity. Our results have important implications to biodiversity conservation in areas sensitive to climate change; for example, high‐altitude areas are likely to continue being biodiversity hotspots, as such future conservation efforts should be concentrated in these areas.

Ecological phytochemistry of Cerrado (Brazilian savanna) plants

The Cerrado (the Brazilian savanna) is one of the vegetation formations of great biodiversity in Brazil and it has experienced strong deforestation and fragmentation. The Cerrado must contain at least 12,000 higher plant species. We discuss the ecological relevance of phytochemical studies carried out on plants from the Cerrado, including examples of phytotoxicity, antifungal, insecticidal and antibacterial activities. The results have been classified according to activity and plant family. The most active compounds have been highlighted and other activities are discussed. A large number of complex biochemical interactions occur in this system. However, only a small fraction of the species has been studied from the phytochemical viewpoint to identify the metabolites responsible for these interactions.

High plant species richness indicates management-related disturbances rather than the conservation status of forests

There is a wealth of smaller-scale studies on the effects of forest management on plant diversity. However, studies comparing plant species diversity in forests with different management types and intensity, extending over different regions and forest stages, and including detailed information on site conditions are missing. We studied vascular plants on 1500 20m×20m forest plots in three regions of Germany (Schwäbische Alb, Hainich-Dün, Schorfheide-Chorin). In all regions, our study plots comprised different management types (unmanaged, selection cutting, deciduous and coniferous age-class forests, which resulted from clear cutting or shelterwood logging), various stand ages, site conditions, and levels of management-related disturbances. We analyzed how overall richness and richness of different plant functional groups (trees, shrubs, herbs, herbaceous species typically growing in forests and herbaceous light-demanding species) responded to the different management types. On average, plant species richness was 13% higher in age-class than in unmanaged forests, and did not differ between deciduous age-class and selection forests. In age-class forests of the Schwäbische Alb and Hainich-Dün, coniferous stands had higher species richness than deciduous stands. Among age-class forests, older stands with large quantities of standing biomass were slightly poorer in shrub and light-demanding herb species than younger stands. Among deciduous forests, the richness of herbaceous forest species was generally lower in unmanaged than in managed forests, and it was even 20% lower in unmanaged than in selection forests in Hainich-Dün. Overall, these findings show that disturbances by management generally increase plant species richness. This suggests that total plant species richness is not suited as an indicator for the conservation status of forests, but rather indicates disturbances.

Antibacterial activity of medicinal plants used as ethnomedicine by the traditional healers of Musiri Thaluk, Trichy District, Tamilnadu, India

The objective of this study was to collect information about medicinal plants and their uses by the knowledge obtained from the traditional healers in Musiri thaluk of Trichy district, Tamilnadu, India. It was also to determine the phytochemical properties and antimicrobial activity of fifteen different plants selected based on spearman rank correlation. The traditional healers of Musiri thaluk, Trichy district used different species of medicinal plants belonging to different families for the treatment of various diseases. Common maximum number of species has been used for fever followed by skin infection, wound healing and antiseptic. Herbs were found to be the most used plants followed by climbers, shrubs and trees. The spearman rank correlation was used to analyse the knowledge about medicinal plants. Antibacterial activity of fifteen medicinal plants (Acalypha fruticosa, Caralluma attenuate, Cissampelos pareira, Elephantopus scaber, Mukia maderaspatensis, Justicia simplex, Lepidagathis cristata, Rhinacanthus nasutus, Sida acuta, Theprosia purpurea,Toddalia asiatica, Tridax procumbens, Tylophora indica, Trichodesma indicum andOldenlandia umbellata) was determined by measuring the diameter of zone of inhibition, that is the mean of triplicates + standard deviation (SD) of three replicates. Of these, T. procumbens and T. indica exhibited more promising bactericidal activity againstStaphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Proteus mirablis andVibrio cholerae. The traditional healers in Trichy district possess rich ethno-botanical knowledge. This study on medicinal plants will attract ethano botanist, phytochemistrist and pharmacologists in identifying many high value medicinal plant species for research of novel antibacterial compound of these medicinal plants. Key words: Antibacterial, medicinal plants, traditional medicine, local healers .

Ab initio calculations of the Fe(II) and Fe(III) isotopic effects in citrates, nicotianamine, and phytosiderophore, and new Fe isotopic measurements in higher plants

Iron is one of the most abundant transition metal in higher plants and variations in its isotopic compositions can be used to trace its utilization. In order to better understand the effect of plant-induced isotopic fractionation on the global Fe cycling, we have estimated by quantum chemical calculations the magnitude of the isotopic fractionation between different Fe species relevant to the transport and storage of Fe in higher plants: Fe(II)-citrate, Fe(III)-citrate, Fe(II)-nicotianamine, and Fe(III)-phytosiderophore. The ab initio calculations show firstly, that Fe(II)-nicotianamine is ∼3‰ (56Fe/54Fe) isotopically lighter than Fe(III)-phytosiderophore; secondly, even in the absence of redox changes of Fe, change in the speciation alone can create up to ∼1.5‰ isotopic fractionation. For example, Fe(III)-phytosiderophore is up to 1.5‰ heavier than Fe(III)-citrate2 and Fe(II)-nicotianamine is up to 1‰ heavier than Fe(II)-citrate. In addition, in order to better understand the Fe isotopic fractionation between different plant components, we have analyzed the iron isotopic composition of different organs (roots, seeds, germinated seeds, leaves and stems) from six species of higher plants: the dicot lentil (Lens culinaris), and the graminaceous monocots Virginia wild rye (Elymus virginicus), Johnsongrass (Sorghum halepense), Kentucky bluegrass (Poa pratensis), river oat (Uniola latifolia), and Indian goosegrass (Eleusine indica). The calculations may explain that the roots of strategy-II plants (Fe(III)-phytosiderophore) are isotopically heavier (by about 1‰ for the δ56Fe) than the upper parts of the plants (Fe transported as Fe(III)-citrate in the xylem or Fe(II)-nicotianamine in the phloem). In addition, we suggest that the isotopic variations observed between younger and older leaves could be explained by mixing of Fe received from the xylem and the phloem.

Direct and indirect associations between plant species richness and productivity in grasslands: regional differences preclude simple generalization of productivity-biodiversity relationships

Plant species richness of permanent grasslands has often been found to be significantly associated with productivity. Concentrations of nutrients in biomass can give further insight into these productivity- plant species richness relationships, e.g. by reflecting land use or soil characteristics. However, the consistency of such relationships across different regions has rarely been taken into account, which might significantly compromise our potential for generalization. We recorded plant species richness and measured above-ground biomass and concentrations of nutrients in biomass in 295 grasslands in three regions in Germany that differ in soil and climatic conditions. Structural equation modelling revealed that nutrient concentrations were mostly indirectly associated with plant species richness via biomass production. However, negative associations between the concentrations of different nutrients and biomass and plant species richness differed considerably among regions. While in two regions, more than 40% of the variation in plant species richness could be attributed to variation in biomass, K, P, and to some degree also N concentrations, in the third region only 15% of the variation could be explained in this way. Generally, highest plant species richness was recorded in grasslands where N and P were co-limiting plant growth, in contrast to N or K (co-) limitation. But again, this pattern was not recorded in the third region. While for two regions land-use intensity and especially the application of fertilizers are suggested to be the main drivers causing the observed negative associations with productivity, in the third region the little variance accounted for, low species richness and weak relationships implied that former intensive grassland management, ongoing mineralization of peat and fluctuating water levels in fen grasslands have overruled effects of current land-use intensity and productivity. Finally, we conclude that regional replication is of major importance for studies seeking general insights into productivity-diversity relationships.

PRESENCE OF LEUCOPLASTS IN SECRETORY CELLS AND OF MONOTERPENES IN THE ESSENTIAL OIL: A CORRELATIVE STUDY

ABSTRACT Analytical and structural studies were performed on 45 species of higher plants containing specialized secretory structures and/or producing essential oils or resins. Significant amounts of volatile compounds, mainly monoterpenes and sesquiterpenes, were recovered from these species. The specialized structures included glandular hairs, resin ducts, secretory cavities and idioblasts. During the ultrastructural investigation, special attention was paid to the plastidome. A number of secretory cells contain true leucoplasts, devoid of thylakoids and ribosomes. The comparison between analytical and structural data showed a very close correlation between the presence of leucoplasts in secretory cells and the significant quantities of monoterpenes (hydrocarbons or oxygenated compounds) in the volatile extract. Moreover, a morphometric estimation of leucoplast development in the cells suggested a quantitative relationship between the expansion of this plastidome and the ratio of monoterpenes in the oil....

A remarkable anniversary: Surtsey becomes 50 years

Announcements ISSN 1948‐6596 A remarkable anniversary: Surtsey becomes 50 years old Every year there is a lot of round anniversaries to celebrate, and 2013 is no exception. Opera fans celebrate Wagner and Verdi, and we biogeogra‐ phers highlight Wallace and the MacArthur– Wilson plot. There is a round anniversary of another kind in 2013. It is 50 years since Surtsey emerged from the sea, in the Vestmanna Archipelago south of Iceland. I still remember the excitement in the press and the extraordinary pictures on black‐and‐ white television. But after a certain time the inter‐ est seemed to dwindle a bit, and in the interna‐ tional press (journalistic as well as scientific) re‐ ports from Surtsey became rather rare. This is strange for at least two reasons. One is that Surtsey was born right in the middle of the debate on two of the most important paradigms in the twentieth century: that of plate tectonics and that on island biogeography. And for both fields the processes on Surtsey yield unique evi‐ dence for the theories. The other reason is that Surtsey was not left alone. Our Icelandic col‐ leagues within geology, geomorphology, oceanog‐ raphy and biology have carefully and meticulously followed the island, and, through repeated and systematic surveys, they have built up a wealth of data on the infancy of an island. They have care‐ fully reported their observations (for example there is a long series of ‘Surtsey Reports’ and a home page where almost everything can be found). But Surtsey does not appear so often in textbooks or reviews as, for example, Galapagos, Krakatau or Hawai’i. Some of the findings are quite extraordi‐ nary. To mention a few: it has been shown that the geochemical transition of volcanic ash to tufa is a question of decades and not of centuries— and erosion of basaltic rocks occurs within the same time scale (Surtsey has lost half of its area already). Furthermore, the build‐up of a plant cover has proved to be rapid: so far roughly 100 species of higher plants have been reported and many of them have disappeared again. This is far more than in the rest of the Vestmanna Archipel‐ ago and around 20% of the entire flora of Iceland. The colonization of birds has also been docu‐ mented and the influence of seabird colonies on vegetation succession has been recorded from scratch. Our Icelandic colleagues have decided to seize the 50 th anniversary as an opportunity both to synthesize the existing knowledge and to com‐ municate it to the international scientific commu‐ nity. They will host an international conference in Reykjavik in August 2013 (12 th –15 th ), focusing on the geological and biological processes on Surtsey. The first and second circulars have been distrib‐ uted, and more information and details can be found on http://www.surtsey.is. The organizers have tried to urge Surt (the equivalent in Nordic mythology to Vulcan/ Hephaistos) to let Surtsey have a younger brother be born just south of El Hierro in the Canary Is‐ lands. He is on the way; let us see whether he makes it in 2013. Henning Adsersen Centre of Macroecology, Evolution, and Climate, Department of Biology, University of Copenhagen, Den‐ mark. adser@bio.ku.dk To post jobs, advertisements, or other announcements please contact the Frontiers of Biogeography editoral office (frontiersofbiogeography@googlemail.com). Advertisements are $50 per quarter page for professional or institutional positions. Announcements are free to members for vacancies in their lab. All advertisements and announcements also appear at no additional cost on the IBS facebook pa‐ ge (in abbreviated form) and on the IBS Blog (in long, or longer form). frontiers of biogeography 5.1, 2013 — © 2013 the authors; journal compilation © 2013 The International Biogeography Society

In Search of Actionable Targets for Agrigenomics and Microalgal Biofuel Production: Sequence-Structural Diversity Studies on Algal and Higher Plants with a Focus on GPAT Protein

The triacylglycerol (TAG) pathway provides several targets for genetic engineering to optimize microalgal lipid productivity. GPAT (glycerol-3-phosphate acyltransferase) is a crucial enzyme that catalyzes the initial step of TAG biosynthesis. Despite many recent biochemical studies, a comprehensive sequence-structure analysis of GPAT across diverse lipid-yielding organisms is lacking. Hence, we performed a comparative genomic analysis of plastid-located GPAT proteins from 7 microalgae and 3 higher plants species. The close evolutionary relationship observed between red algae/diatoms and green algae/plant lineages in the phylogenetic tree were further corroborated by motif and gene structure analysis. The predicted molecular weight, amino acid composition, Instability Index, and hydropathicity profile gave an overall representation of the biochemical features of GPAT protein across the species under study. Furthermore, homology models of GPAT from Chlamydomonas reinhardtii, Arabidopsis thaliana, and Glycine max provided deep insights into the protein architecture and substrate binding sites. Despite low sequence identity found between algal and plant GPATs, the developed models exhibited strikingly conserved topology consisting of 14α helices and 9β sheets arranged in two domains. However, subtle variations in amino acids of fatty acyl binding site were identified that might influence the substrate selectivity of GPAT. Together, the results will provide useful resources to understand the functional and evolutionary relationship of GPAT and potentially benefit in development of engineered enzyme for augmenting algal biofuel production.

An upstream regulator of the 26S proteasome modulates organ size in Arabidopsis thaliana

In both animal and plant kingdoms, body size is a fundamental but still poorly understood attribute of biological systems. Here we report that the Arabidopsis NAC transcription factor 'Regulator of Proteasomal Gene Expression' (RPX) controls leaf size by positively modulating proteasome activity. We further show that the cis-element recognized by RPX is evolutionarily conserved between higher plant species. Upon over-expression of RPX, plants exhibit reduced growth, which may be reversed by a low concentration of the pharmacological proteasome inhibitor MG132. These data suggest that the rate of protein turnover during growth is a critical parameter for determining final organ size.

Novel and Bioactive Compounds from the Malayan Flora; Recent Findings and Challenges

Malaysia is one of the seventeen megadiverse countries in the world. Its flora is home to an estimated 15,000 higher plant species and it is widely known that plants are efficient manufacturers of compounds with highly diversed molecular structures and an unending array of biological activities. Therefore, it is logical to assume that a multitude of molecules and their activities are yet to be discovered from this beautiful and immense flora. In fact, our experience with plants from various families; Annonaceae, Apocynaceae, Lauraceae, Meliaceae and Rubiaceae, have evidenced that many types of interesting and unique compounds were synthesized by these plants; alkaloids, triterpenes, limonoids, lignans, coumarins and many others. In this presentation, recent findings on some novel and bioactive compounds from some higher plants shall be communicated which includes some mechanisms in their mode of action for example the novel malayanine A and B from Chisocheton erythrocarpus and the neuroprotective and acetylcholinesterase inhibiting mesuagenins isolated from Mesua species. In addition, as Natural Products and Drug Discovery is an important research area in Malaysia, the challenges and possible directions in this field shall be discussed briefly. For instance, how can we, the natural products scientists relate our findings and knowledge to the society and then further contribute to the enhancement of its well-being?