133,136 research outputs found
Insights into the Musa genome: Syntenic relationships to rice and between Musa species
No full textAbstract Background Musa species (Zingiberaceae, Zingiberales) including bananas and plantains are collectively the fourth most important crop in developing countries. Knowledge concerning Musa genome structure and the origin of distinct cultivars has greatly increased over the last few years. Until now, however, no large-scale analyses of Musa genomic sequence have been conducted. This study compares genomic sequence in two Musa species with orthologous regions in the rice genome. Results We produced 1.4 Mb of Musa sequence from 13 BAC clones, annotated and analyzed them along with 4 previously sequenced BACs. The 443 predicted genes revealed that Zingiberales genes share GC content and distribution characteristics with eudicot and Poaceae genomes. Comparison with rice revealed microsynteny regions that have persisted since the divergence of the Commelinid orders Poales and Zingiberales at least 117 Mya. The previously hypothesized large-scale duplication event in the common ancestor of major cereal lineages within the Poaceae was verified. The divergence time distributions for Musa-Zingiber (Zingiberaceae, Zingiberales) orthologs and paralogs provide strong evidence for a large-scale duplication event in the Musa lineage after its divergence from the Zingiberaceae approximately 61 Mya. Comparisons of genomic regions from M. acuminata and M. balbisiana revealed highly conserved genome structure, and indicated that these genomes diverged circa 4.6 Mya. Conclusion These results point to the utility of comparative analyses between distantly-related monocot species such as rice and Musa for improving our understanding of monocot genome evolution. Sequencing the genome of M. acuminata would provide a strong foundation for comparative genomics in the monocots. In addition a genome sequence would aid genomic and genetic analyses of cultivated Musa polyploid genotypes in research aimed at localizing and cloning genes controlling important agronomic traits for breeding purposes.</p
Analysis of non-TIR NBS-LRR resistance gene analogs in <it>Musa acuminata </it>Colla: Isolation, RFLP marker development, and physical mapping
No full textAbstract Background Many commercial banana varieties lack sources of resistance to pests and diseases, as a consequence of sterility and narrow genetic background. Fertile wild relatives, by contrast, possess greater variability and represent potential sources of disease resistance genes (R-genes). The largest known family of plant R-genes encode proteins with nucleotide-binding site (NBS) and C-terminal leucine-rich repeat (LRR) domains. Conserved motifs in such genes in diverse plant species offer a means for isolation of candidate genes in banana which may be involved in plant defence. Results A computational strategy was developed for unbiased conserved motif discovery in NBS and LRR domains in R-genes and homologues in monocotyledonous plant species. Degenerate PCR primers targeting conserved motifs were tested on the wild cultivar Musa acuminata subsp. burmannicoides, var. Calcutta 4, which is resistant to a number of fungal pathogens and nematodes. One hundred and seventy four resistance gene analogs (RGAs) were amplified and assembled into 52 contiguous sequences. Motifs present were typical of the non-TIR NBS-LRR RGA subfamily. A phylogenetic analysis of deduced amino-acid sequences for 33 RGAs with contiguous open reading frames (ORFs), together with RGAs from Arabidopsis thaliana and Oryza sativa, grouped most Musa RGAs within monocotyledon-specific clades. RFLP-RGA markers were developed, with 12 displaying distinct polymorphisms in parentals and F1 progeny of a diploid M. acuminata mapping population. Eighty eight BAC clones were identified in M. acuminata Calcutta 4, M. acuminata Grande Naine, and M. balbisiana Pisang Klutuk Wulung BAC libraries when hybridized to two RGA probes. Multiple copy RGAs were common within BAC clones, potentially representing variation reservoirs for evolution of new R-gene specificities. Conclusion This is the first large scale analysis of NBS-LRR RGAs in M. acuminata Calcutta 4. Contig sequences were deposited in GenBank and assigned numbers ER935972 – ER936023. RGA sequences and isolated BACs are a valuable resource for R-gene discovery, and in future applications will provide insight into the organization and evolution of NBS-LRR R-genes in the Musa A and B genome. The developed RFLP-RGA markers are applicable for genetic map development and marker assisted selection for defined traits such as pest and disease resistance.</p
Variable number of tandem repeat markers in the genome sequence of Mycosphaerella fijiensis, the causal agent of black leaf streak disease of banana (Musa spp)
No full textABSTRACT. We searched the genome of Mycosphaerella fijiensis for molecular markers that would allow population genetics analysis of this plant pathogen. M. fijiensis, the causal agent of banana leaf streak disease, also known as black Sigatoka, is the most devastating pathogen attacking bananas (Musa spp). Recently, the entire genome sequence of M. fijiensis became available. We screened this database for VNTR markers. Forty-two primer pairs were selected for validation, based on repeat type and length and the number of repeat units. Five VNTR markers showing multiple alleles were validated with a reference set of isolates from different parts of the world and a population from a banana plantation in Costa Rica. Polymorphism information content values varied from 0.6414 to 0.7544 for the reference set and from 0.0400 and 0.7373 for the population set. Eighty percent of the polymorphism information content values were above 0.60, indicating that the markers are highly informative. These markers allowed robust scoring of agarose gels and proved to be useful for variability and population genetics studies. In conclusion, the strategy we developed to identify and validate VNTR markers is an efficient means to incorporate markers that can be used for fungicide resistance management and to develop breeding strategies to control banana black leaf streak disease. This is the first report of VNTR-minisatellites from the M. fijiensis genome sequence. Key words: Molecular markers; VNTRs; Genetic diversity; Population genetics; Black Sigatok
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Taxa de multiplicação de mudas micropropagadas de bananeira cv. Grande Naine e cv. Prata Catarina influenciada pela fase de estabelecimento de cultura
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, Programa de Pós-Graduação em Recursos Genéticos Vegetais, Florianópolis, 2015.A bananeira é a segunda fruteira mais cultivada do mundo, sendo o Brasil o quinto no ranking, com 6,8% da produção mundial de banana. No ano de 2014, a estimativa da área de produção brasileira foi de 490,1 mil hectares, produção de 7,18 milhões de toneladas de frutas (EPAGRI/CEPA, 2014). Nas últimas décadas, a produção se expandiu na maioria dos países produtores; passou de 35 milhões para 102 milhões de toneladas entre as safras 1978 e de 2012, parte deste aumento de produção se deve ao avanço tecnológico, principalmente devido disponibilidade de material genético diversificado e de mudas com valor agregado, principalmente qualidade fitossanitária obtida através de técnicas biotecnológicas. Apesar das biofábricas terem protocolos de micropropagação bem sucedidos, os mesmos não são suficientes para atenderem a demanda com qualidade e quantidade de mudas. Nos últimos anos os sistemas de propagação, em larga escala, não atingiu o número de mudas desejadas, mesmo com a utilização de biorreatores de imersão temporária, o qual tem sido associado ao aumento dos riscos de surgimento de variantes somaclonais. O presente trabalho teve por objetivo mostrar o comportamento das culturas in vitro de Musa acuminata (AAA) cv. Grande Naine e de Musa acuminata x Musa balbisiana (AAB) cv. Prata Catarina, submetidas a alterações no protocolo de micropropagação, comumente utilizado em biofábricas, visando obter maior taxa de multiplicação. Utilizando-se de material vegetal proveniente da coleção da EPAGRI/EEI, o trabalho foi dividido em duas etapas: fase de estabelecimento de cultura e fase de multiplicação. Na fase de estabelecimento, utilizou-se como meio base a formulação MS, acrescida de 1 mg.L-1 de BAP e 1 mg.L-1 de ANA, tendo como variáveis nos tratamentos propostos: aumento do tempo de cultivo in vitro; alterações de concentração de sais e adição de diferentes fitormônios. Para a fase de multiplicação utilizou-se as culturas provenientes da fase de estabelecimento, em cinco subcultivos de 30 dias, utilizando a formulação do meio MS e tendo como variáveis: alteração no estado físico (sólido/liquido), adição de BAP e adição de BAP/ANA. O meio MS, acrescido de 2,5 mg.L-1 de BAP promoveu a maior taxa de multiplicação, em ambas as cultivares estudadas. As melhores taxas de multiplicação quando consideradas fases de estabelecimento e multiplicação, para cultivar Grande Naine, foram obtidas em meio MS, acrescido de 1 mg.L-1 de BAP e 1 mg.L-1 de ANA por 90 dias em estabelecimento de cultura, utilizando na sequencia meio MS com 2,5 mg.L-1 de BAP para multiplicação em 5 subcultivos de 30dias consecutivos, alcançando taxas de multiplicação de 356 brotos por explante inicial, superior em 5 vezes ao obtido no tratamento similar ao praticado em biofábricas. Quanto a cultivar Prata Catarina o desempenho obtido não foi superior ao alcançado em biofábricas e os tratamentos não apresentaram diferenças estatísticas significativas. Foi utilizado meio MS com 50% dos sais da formulação para prover crescimento e enraizamento. Na fase de aclimatização, o método utilizado foi eficiente gerando número total de mudas para as cultivares Grande Naine e Prata Catarina de 8.995 e 3.911, respectivamente. O estudo indicou que alterações na fase de estabelecimento de cultura resultam em aumento da taxa de multiplicação para o cv. Grande Naine, enquanto que para o cv. Prata Catarina não apresenta efeito significativo.Abstract : The Banana is the second most cultivated fruit tree in the world, and Brazil is the fifth in the ranking, with 6.8% of the world production. In the year 2014, the estimate of Brazilian production area was 490,100 hectares, producing 7.18 million tons of fruit (EPAGRI/CEPA, 2014). In the last decades, production has expanded in most producing countries, from 35 million tons in 1978 to 102 million tons in 2012, part of this increase in production is due to technological advances related to the availability of more genetically diverse germplasm and of seedlings with higher sanitary quality obtained through biotechnological techniques. Despite successful micropropagation protocols adopted by biofactories , they are not sufficient to meet the demand with quality and quantity of seedlings. In recent years propagation systems on a large scale has not reached the desired number of plants, even with the use of temporary immersion bioreactor, which has been associated with increased risks of onset of somaclonal variants. This study aimed to show the behavior of in vitro cultures of Musa acuminata (AAA) cv. Grande Naine and of Musa acuminata x Musa balbisiana (AAB) cv. Prata Catarina when changes in the micropropagation protocol were made compared to the traditional protocols, for an increase in the micropropagarion rate. The work was divided in two phases, namely culture establishment and culture multiplication. The explants used came from a field collection established at Epagri/Itajaí Research Station. In the phase of establishment of culture, MS base medium plus 1 mg.L-1 BAP and 1 mg.L-1 NAA was used, and there was an increase in the in vitro culture time, as well as changes in the salt concentration and in the phytohormones used. For the multiplication phase, materials generated from five subcultures of 30 days each were used, and changes in the physical state (solid/liquid) and in the concentration of cytokinin (BAP) and cytokinin/auxin (NAA). The treatment that consisted of MS medium plus 2.5 mg.L-1 BAP promotedthe highest multiplication rate in both cultivars. For the cultivar Grande Naine, the highest multiplication rates for both the establishment and the multiplication phases were obtained when MS medium plus 1 mg.L-1 de BAP and 1 mg.L-1 de NAA for 90 establishing days in culture was used, followed by multiplication in MS medium with 2.5 mg.L-1 BAP in five subcultures of 30 days each; the multiplication rates obtained were 356 shoots per initial explant, five times higher than that obtained in a similar treatment adopted by biofactories. However, for the cultivar Prata Catarina, the performance of the treatments was not statistically different from the performance of the traditional protocols adopted by biofactories. Half-strength MS medium was used to promote growth and root development. The method adopted in the acclimatization stage was efficient, generating 8,995 and 3,911 plants for the cultivars Grande Naine and Prata Catarina, respectively. The study indicated that change in culture establishment phase result in increased multiplication rate for the cv. Grand Naine, while for cv. Prata Catarina has no significant effect
Improving plantain ( Musa spp. AAB) yields on smallholder farms in West and Central Africa
No full textPlantain is an important staple in West and Central Africa, where it is predominantly grown by smallholder farmers. On-farm data are rare but yields are considered to be low. We collated actual yields in the region, reviewed regional plantain research published from 1976 to 2013, then estimated what yields would be attainable on smallholder farms if the proven, best-fit innovations were adopted. Mean actual yields reported ranged from 2.9 to 8.9 Mg ha−1 with a mean of 5.7 Mg ha−1 for False horn plantain and 4.5 to 10.2 Mg ha−1 with a mean of 7.8 Mg ha−1 for French plantain. Experiments found dealt with: cultural practices, particularly intercropping; abiotic factors such as fertiliser, mulch application and irrigation; biotic factors, predominantly sucker sanitation methods, but including three controlled yield loss studies on nematodes and black sigatoka; landrace comparisons and the introduction of improved cultivars, predominantly those exhibiting black sigatoka-tolerance. We conclude that intercropping should be retained according to farmer preference as there was no evidence of yield reductions for plantain. Boiling water treatment of suckers should be universally recommended. Inputs, whether mulch or K fertiliser up to 300 kg ha−1 should be applied as both reduced plant losses and increased bunch mass. With the highest yielding local landrace type, on-farm yields could be increased from 7.8 Mg ha−1 to 35.5 Mg ha−1 with purchased inputs or to 23.7 Mg ha−1 without purchased inputs
Musa b. Ukbe’nin (v. 141/ 758) Siyer’e dair rivayetlerinin değerlendirilmesi (hz. Muhammed’in nübüvvetine kadar)
No full textHz. Muhammed’in hayatının peygamberlik öncesi dönemi hakkında İslam Tarihi kaynaklarında oldukça farklı rivayetler mevcuttur. Üstelik bu farklılık çok erken dönemlerden itibaren mevcuttur. Bu farklılıkların mümkünse sebeplerinin anlaşılabilmesi veya en azından hangi bilginin daha güvenilir ve tercihe şayan olduğunun belirlenebilmesi amacıyla İslami ilimlerin kendine has yöntemi olan “isnad” kullanılarak ve İslam tarihinin çok geniş sahası ilk dönemle sınırlanıp Megāzî müellifi olduğu iddia edilen ve bu sahada hemen her olayın farklı bir anlatımına rastladığımız Musa b. Ukbe’nin rivayetleri tezin merkezinde tutulmak suretiyle konu ile ilgili diğer rivayetlerin değerlendirilmesi önemli görülmektedir. Zira böylece erken dönem İslam tarihi çalışmalarında çok problemli bir alan olan Hz. Muhammed’in peygamberlik öncesi dönemi hem aydınlatılma hem de çeşitli spekülasyonlardan arındırılma imkanına sahip olacaktır. Ukbe, Megāzî, Siyer, İslam Tarihi, Hz. Muhammed, Peygamberlik Öncesi, Rivayet.There are widely different narratives about the pre-prophecy life of the Prophet Muhammad in the early Islamic sources. It seems important to review relative narratives about the subject and the thesis focuses on the narratives of Musa b. Uqba, the author of a maghazi, who uses the way of “isnad”, a specific method in Islamic scholarship to understand variations. This would help us identify reliable data in the early Islamic period. Thus, it’ll be possible to light and purify from speculations the pre-prophecy life of the Prophet Muhammad, which is very problematical area in the early Islamic history. Key Words: Musa b. Uqba, Maghazi, Siyar, History of İslam, Mohammed, Pre-prophecy, Narrative
<b>"Amuri"—an elixir from <i style="">Musa paradisiaca </i>L</b>
No full text168-176Indian traditional systems of medicine like
Ayurveda and Siddha offer medicines called Kayakalpa drugs for rejuvenation and
for treating refractive diseases. Amuri is one such drug described in many
Siddha texts and manuscripts. An unpublished Siddha palm leaf manuscript Kanranadi Vakkiyam describes preparation
of Amuri from Banana tree. An attempt has been made in this work to extract
Amuri from Musa paradisiaca L.,
standardize its yield and characterize the liquid using physico-chemical
parameter
In vivo and in vitro germination of Musa violascens and Musa borneensis seeds
No full textMusa is a large perennial monocotyledonous herbaceous plant genus in Musaceae family native to the
Indo-Malesia, Asian and Australian tropics. It has five taxonomic sections with two of them contain edible
bananas. Banana and plantain are considered as an important food crop for people as it ranked fourth
globally after rice, wheat and maize. Banana is either consumed raw as fruits or cooked, steamed, boiled,
grilled, baked, and fried to make into chips, dessert, snack and food like curry and soup. The plant can be
used as silage, rope, cordage, garlands, shelter, clothing, smoking materials and ceremonial and religious
uses (Nelson et al., 2006). The edible cultivated varieties were derived from the hybridization between two
wild species namely Musa acuminata Cola and Musa Balbisiana Cola which gave rise to different
genomic groupings namely AA, AAA, AB, ABB/BBB, ABBB (Hakkinen and Hong, 2007Suhana et al.,
2012). The increasing areas of banana plantations in tropical countries are threatened by the continuous
pests and diseases problems such as the appearance and spread of the virulent form of Sigatoka leaf spot
disease. Thus, awareness has been increased among banana breeders in order to produce new cultivated
varieties with the disease-resistant characteristics (Pancholi et al., 1995). However, breeding programs are
difficult to be done in cultivated Musa. This is due to the nature of fruits from cultivated Musa species
which are normally sterile and very low fertility. Cultivated Musa species are known as its parthenocarpic
characteristics where fruits are produced without pollination and fertilization thus seeds are not form
(Nelson et al., 2006). (Copied from article)
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