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Search Results: 1 - 10 of 9443 matches for " molecular breeding "
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Evaluating Human Resource Capacity for Crop Breeding in National Programs in Africa and South and Southeast Asia  [PDF]
Ndeye Ndack Diop, Fredrick Okono, Jean-Marcel Ribaut
Creative Education (CE) , 2013, DOI: 10.4236/ce.2013.410A011

Plant breeders must keep abreast of the rapid evolution of new technologies, and also implement information management strategies that efficaciously handle the ever growing amount of data required for efficient integrated breeding. Updated training for breeders is critical to build relevant human resource capacity, particularly in developing countries whose breeding programs suffer a lack of staff with diverse expertise. The CGIAR Generation Challenge Programme is leading such a capacity-building initiative. A survey was conducted among course nominees to establish a baseline of breeder level of education, knowledge and skills in analyzing data and their involvement in molecular breeding programs. The breeders were mainly from three regions: West and Central Africa, East and Southern Africa, and South and Southeast Asia, and also included a few participants from North Africa. Many of the breeders from all the regions held or were working towards a PhD. Gender balance was low, principally in West and Central Africa, where less than 15% of the breeders were women. Between 57% and 73% of the breeders surveyed in the different regions were involved in molecular breeding projects at regional or international level. The Use of multiple software tools by individual breeders for data analysis was low for breeders from all the regions, with most using 1 - 3 packages. A lack of high data-analysis capacity will be a problem in an era where integration of genomics and phenotypic data in breeding programs is essential to efficiently deliver improved cultivars.

Development and Characterization of SSR Markers in Proso Millet Based on Switchgrass Genomics  [PDF]
Santosh G. Rajput, Tammy Plyler-Harveson, Dipak K. Santra
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.51023

Proso millet (Panicummiliaceum) has highwater use efficiency (WUE), a short growing-season, and is highly adapted to a semi-arid climate. Genomic resources for proso millet are very limited. Large numbers of DNA markers and other genomic tools in proso millet can readily be developed by using genomic resources in related grasses. The objectives of the present report were to 1) test and characterize switchgrass SSR markers for use in proso millet, and 2) elucidate repeat-motifs in proso millet based on new SSR marker analysis. A total of 548 SSR markers were tested on 8 proso millet genotypes. Out of these, 339 amplified SSR markers in proso millet. This showed that 62% of the switchgrass SSR markers were transferable to proso millet. Of these 339 markers, 254 were highly polymorphic among the 8 proso genotypes. The resolving power of these 254 polymorphic SSR markers ranged from 0.25-14.75 with an average of 2.71. The 254 polymorphic SSR markers amplified 984 alleles in the ranges of 50 bp to 1300 bp. The majority of the SSR markers (221 of 254) amplified dinucleotide repeats. Based on SSR marker analysis, AG/GA was the most abundant repeat-motifs in proso millet. Switchgrass genomic information seems to be the most useful for developing DNA markers in proso millet. Markers developed in this study will be helpful for linkage

Molecular characterization of Cuban endemism Carica cubensis Solms using random amplified polymorphic DNA (RAPD) markers  [PDF]
Jesús Rodríguez, Pedro Rodríguez, María E. González, Pedro Martínez-Gómez
Agricultural Sciences (AS) , 2010, DOI: 10.4236/as.2010.13012
Abstract: The objective of this work is to present an appropriate set of RAPD (random amplified polymorphic DNA) markers using single and multiplex PCR analysis suitable for the characterization of the endemic Cuban species Carica cubensis and the establishment of genetic relationships with the cultivated species Carica papaya. RAPD markers presented a high level of polymorphism. In addition, the incorporation of more than one RAPD primer in the PCR analysis increased the number of obtained bands and the polymorphism of these bands. A total of 73 RAPD bands were detected (45 of them polymorphic) with the nine RAPD markers assayed using single and multiplex PCR analysis. Results demonstrated a reduced genetic variability within the tested Carica cubensis accessions. The observed clustering in this species could be better explained according to geographic proximity and can indicate the similar precedence of the isolated studied populations. C. cubensis seem to be subspecies of C. papaya adapted to the environmental conditions of the mountains of Cuba or a endemic species close to C. papaya. The implications of these results in the creation of effective germplasm core collection in Carica species have been also discussed.
Databasing Molecular Identities of Sugarcane (Saccharum spp.) Clones Constructed with Microsatellite (SSR) DNA Markers  [PDF]
Yong-Bao Pan
American Journal of Plant Sciences (AJPS) , 2010, DOI: 10.4236/ajps.2010.12011
Abstract: This paper reports the development of the first SSR marker-based sugarcane (Saccharum spp.) molecular identity database in the world. Since 2005, 1,025 sugarcane clones were genotyped, including 811 Louisiana, 45 Florida, 39 Texas, 130 foreign, and eight consultant/seed company clones. Genotyping was done on a fluorescence-capillary electrophoresis detection platform involving 21 highly polymorphic SSR markers that could potentially amplify 144 distinctive DNA fragments. Genotyping data were processed with the GeneMapper? software to reveal electrophoregrams that were manually checked against the 144 fragments. The presence (A) or absence (C) of these 144 fragments in any sugarcane clone was recorded in an affixed sequence order as a DNAMAN® file to represent its molecular identity being achieved into a local molecular identity database. The molecular identity database has been updated annually by continued genotyping of newly assigned sugarcane clones. The database provides molecular descriptions for new cultivar registration articles, enables sugarcane breeders to identify mis-labeled sugarcane clones in crossing programs and determine the paternity of cross progeny, and ensures the desired cultivars are grown in farmers’ fields.
Molecular Markers Associated with Ph-3 Gene Conferring Late Blight Resistance in Tomato  [PDF]
Dilip R. Panthee, Randy G. Gardner, Ragy Ibrahem, Candice Anderson
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.613216
Abstract: Late blight (LB), caused by the oomycete Phytophthora infestans, is one of the most devastating diseases of tomato. Three major genes Ph-1, Ph-2 and Ph-3 conferring resistance to LB have been identified and mapped to the chromosomes 7, 10 and 9, respectively. However, PCR-based molecular markers associated with these genes are limited. Molecular markers are extremely useful in the screening and selection of tomato lines for the development of LB resistant genotypes. The objective of this study was to identify molecular markers associated with Ph-3 gene conferring LB resistance in tomato. Four co-dominant markers were found to be associated with Ph-3, all of which were sequence characterized amplified region (SCAR) type. Breeding lines and cultivars were inoculated with a field isolate of Phytophthora infestans to collect phenotypic data on disease resistance. Genotypic data from molecular markers associated with Ph-3 were in close agreement with the phenotypic data for the lines tested. With the verification of genotypic data from novel molecular markers in known genotypes supported by phenotypic data, the novel molecular markers may be useful in screening tomato populations aiming to develop LB resistant genotypes or cloning the LB resistant genes.
AFLP and SRAP markers linked to the mj gene for root-knot nematode resistance in cucumber
Devran, Zübeyir;Firat, Ahmet Fikret;T?r, Mahmut;Mutlu, Nedim;Elek?io?lu, Ibrahim Halil;
Scientia Agricola , 2011, DOI: 10.1590/S0103-90162011000100017
Abstract: root-knot nematodes (meloidogyne spp.) are an important worldwide pest of cucumber (cucumis sativus l.). molecular markers linked to the javanese root-knot nematode (m. javanica) resistance gene mj in cucumber may aid marker assisted selection. one-hundred aflp (ecori-msei) and 112 srap were used to screen resistant and susceptible parents for polymorphisms to develop molecular markers linked to the mj gene. of the 100 aflp primers, 92 produced bands and two yielded candidate markers (e-att/m-caa and e-aac/m-ctg). these two bands were cut off from polyacrylamide gel, cloned and sequenced. primers designed from the sequences did not yield polymorphic bands between the parents. in addition, the sequences did not contain any restriction site or indel to be used to convert them to caps or scar markers. the two sequences obtained from polymorphic aflp markers were used primarily to design d1f, d1r, d17f and d17r primers. srap forward and reverse primers were used in combination with these four specific primers to search for polymorphisms between parents. of the 112 primer combinations 11 yielded polymorphisms between parents. mapmaker exp 3.0 software was used to analyze the 11 markers. two markers were identified that flanked the mj gene at distance of 16.3 and 19.3 cm. the results indicated that these markers should be useful to develop molecular markers flanking the mj gene.
Microsatellite diversity and heterozygosity of parents of a cocoa breeding population
Milton Macoto Yamada,Fábio Gelape Faleiro,Acassi Batista Flores,Uilson Vanderlei Lopes
Crop Breeding and Applied Biotechnology , 2009,
Abstract: The purpose of this study was to determine the genetic diversity and heterozygosity of 26 clones used asparents of 27 families. The populations are being evaluated by the Comiss o Executiva do Plano da Lavoura Cacaueira(CEPLAC), in the state of BA. Nine of these clones are currently being recommended to farmers, while six others were used ascontrol. The seven microsatellite generated 52 alleles with a mean of seven alleles/locus and genetic distance ranging from0.17 to 0.90. This indicates a wide distribution of accessions and high variability. The heterozygosity ranged from 20% to86%, and more than 50% of the loci were heterozygous in 79% of the clones. Although the selection of the parents forpopulations was not based on genetic distances, the high genetic diversity and heterozygosity of parents indicate highlysegregating populations that make the selection of trees of interest possible, due to the variability.
Marker-assisted selection for quantitative traits
Schuster, Ivan;
Crop Breeding and Applied Biotechnology , 2011, DOI: 10.1590/S1984-70332011000500008
Abstract: although thousands of scientific articles have been published on the subject of marker-assisted selection (mas) and quantitative trait loci (qtl), the application of mas for qtl in plant breeding has been restricted. among the main causes for this limited use are the low accuracy of qtl mapping and the high costs of genotyping thousands of plants with tens or hundreds of molecular markers in routine breeding programs. recently, new large-scale genotyping technologies have resulted in a cost reduction. nevertheless, the mas for qtl has so far been limited to selection programs using several generations per year, where phenotypic selection cannot be performed in all generations, mainly in recurrent selection programs. methods of mas for qtl in breeding programs using self-pollination have been developed.
Marker-assisted selection for quantitative traits
Ivan Schuster
Crop Breeding and Applied Biotechnology , 2011,
Abstract: Although thousands of scientific articles have been published on the subject of marker-assisted selection (MAS) andquantitative trait loci (QTL), the application of MAS for QTL in plant breeding has been restricted. Among the main causes for thislimited use are the low accuracy of QTL mapping and the high costs of genotyping thousands of plants with tens or hundreds ofmolecular markers in routine breeding programs. Recently, new large-scale genotyping technologies have resulted in a costreduction. Nevertheless, the MAS for QTL has so far been limited to selection programs using several generations per year, wherephenotypic selection cannot be performed in all generations, mainly in recurrent selection programs. Methods of MAS for QTL inbreeding programs using self-pollination have been developed.
Acta Biológica Colombiana , 2011,
Abstract: cassava (manihot esculenta) is the main source of calories for more than 1,000 millions of people around the world and has been consolidated as the fourth most important crop after rice, corn and wheat. cassava is considered tolerant to abiotic and biotic stress conditions; nevertheless these characteristics are mainly present in non-commercial varieties. genetic breeding strategies represent an alternative to introduce the desirable characteristics into commercial varieties. a fundamental step for accelerating the genetic breeding process in cassava requires the identification of genes associated to these characteristics. one rapid strategy for the identification of genes is the possibility to have a large collection of ests (expressed sequence tag). in this study, a complete analysis of cassava ests was done. the cassava ests represent 80,459 sequences which were assembled in a set of 29,231 unique genes (unigen), comprising 10,945 contigs and 18,286 singletones. these 29,231 unique genes represent about 80% of the genes of the cassava’s genome. between 5% and 10% of the unigenes of cassava not show similarity to any sequences present in the ncbi database and could be consider as cassava specific genes. a functional category was assigned to a group of sequences of the unigen set (29%) following the gene ontology vocabulary. the molecular function component was the best represented with 43% of the sequences, followed by the biological process component (38%) and finally the cellular component with 19%. in the cassava ests collection, 3,709 microsatellites were identified and they could be use as molecular markers. this study represents an important contribution to the knowledge of the functional genomic structure of cassava and constitutes an important tool for the identification of genes associated to agricultural characteristics of interest that could be employed in cassava breeding programs.
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