Molecular Breeding (molecular + breeding)

Distribution by Scientific Domains


Selected Abstracts


Prospects for molecular breeding of barley

ANNALS OF APPLIED BIOLOGY, Issue 1 2003
W T B THOMAS
Summary Data from UK Recommended List Trials showed that the introduction of new cultivars of spring and winter barley has maintained a significant increase in yield over time, whereas there has been no significant improvement in hot water extract, the major determinant of good malting quality, in either crop. Commercial barley breeding is based upon phenotypic selection, and the introduction of molecular breeding methods must either increase the rate of advance, or offer an improvement in the cost-effectiveness of breeding programmes. Molecular breeding can be applied to either single gene or polygenic characters but is not widely used in commercial barley breeding, other than as a marker for resistance to the Barley Yellow Mosaic Virus complex. There are many reports of potential targets for use in molecular breeding but the few validation studies that have been carried out to date are disappointing. Results from genomics studies are likely to lead to the identification of key candidate genes, which can be associated with economically important characters through co-location on certain chromosomal regions. Associations between candidate gene sequence haplotypes and phenotypic characteristics is expected to identify allelic combinations, which are most frequently observed in successful cultivars, that can be used in molecular breeding of barley on a commercial scale. [source]


Activity and mode of action against fungal phytopathogens of bovine lactoferricin-derived peptides

JOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2006
A. Mu˝oz
Abstract Aim:, To evaluate the activity against fungal phytopathogens of two synthetic peptides derived from the protein bovine lactoferricin: the antibacterial active core of six amino acid residues (LfcinB20,25) and an extension of 15 amino acids (LfcinB17,31). Methods and Results:,In vitro activity against fungal pathogens was determined and compared with that against model micro-organisms. Activity was demonstrated against fungi of agronomic relevance. Distinct antimicrobial properties in vitro were found for the two peptides. LfcinB17,31 had growth inhibitory activity higher than LfcinB20,25. However, LfcinB17,31 was not fungicidal to quiescent conidia of Penicillium digitatum at the concentrations assayed, while LfcinB20,25 killed conidia more efficiently. Microscopical observations showed that the mycelium of P. digitatum treated with LfcinB17,31 developed alterations of growth, sporulation and chitin deposition, and permeation of hyphal cells. In experimental inoculations of mandarins, both peptides showed limited protective effect against the disease caused by P. digitatum. Conclusions:, LfcinB20,25 and LfcinB17,31 peptides were shown to have antimicrobial activity against plant pathogenic filamentous fungi, with distinct properties and mode of action. Significance and Impact of the Study:, LfcinB20,25 and LfcinB17,31 peptides offer novel alternatives to develop resistant plants by molecular breeding. [source]


Allelopathy in crop/weed interactions , an update

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 4 2007
Regina G Belz
Abstract Since varietal differences in allelopathy of crops against weeds were discovered in the 1970s, much research has documented the potential that allelopathic crops offer for integrated weed management with substantially reduced herbicide rates. Research groups worldwide have identified several crop species possessing potent allelopathic interference mediated by root exudation of allelochemicals. Rice, wheat, barley and sorghum have attracted most attention. Past research focused on germplasm screening for elite allelopathic cultivars and the identification of the allelochemicals involved. Based on this, traditional breeding efforts were initiated in rice and wheat to breed agronomically acceptable, weed-suppressive cultivars with improved allelopathic interference. Promising suppressive crosses are under investigation. Molecular approaches have elucidated the genetics of allelopathy by QTL mapping which associated the trait in rice and wheat with several chromosomes and suggested the involvement of several allelochemicals. Potentially important compounds that are constitutively secreted from roots have been identified in all crop species under investigation. Biosynthesis and exudation of these metabolites follow a distinct temporal pattern and can be induced by biotic and abiotic factors. The current state of knowledge suggests that allelopathy involves fluctuating mixtures of allelochemicals and their metabolites as regulated by genotype and developmental stage of the producing plant, environment, cultivation and signalling effects, as well as the chemical or microbial turnover of compounds in the rhizosphere. Functional genomics is being applied to identify genes involved in biosynthesis of several identified allelochemicals, providing the potential to improve allelopathy by molecular breeding. The dynamics of crop allelopathy, inducible processes and plant signalling is gaining growing attention; however, future research should also consider allelochemical release mechanisms, persistence, selectivity and modes of action, as well as consequences of improved crop allelopathy on plant physiology, the environment and management strategies. Creation of weed-suppressive cultivars with improved allelopathic interference is still a challenge, but traditional breeding or biotechnology should pave the way. Copyright ę 2006 Society of Chemical Industry [source]


Transcriptomic study of apricot fruit (Prunus armeniaca) ripening among 13 006 expressed sequence tags

PHYSIOLOGIA PLANTARUM, Issue 3 2005
JÚr˘me Grimplet
To improve the knowledge of fruit ripening and to provide genomic resources for molecular breeding of apricot (Prunus armeniaca L), 13 006 expressed sequence tags (ESTs) were generated from three ,zap cDNA libraries of the pericarp tissues at different stages of development (Physiol Plant 105: 294,303), yielding 5219 (40%) Unigenes. At this stage, the very low interlibrary redundancy indicated that EST sampling of the transcriptome of apricot pericarp is still far from being saturated. Seventy-six percent of Unigenes displayed homologies with public sequences and were clustered into functional categories. The largest expressed categories were related to primary metabolism, stress response, and protein synthesis. Electronic Northern analysis revealed that stress-related proteins and cell wall modification-related enzymes strongly increased during ripening. Among 448 isoproteins (amino acid-level isogenes) detected in the Unigene set, 186 (42%) displayed significant homologies in their coding regions (nucleic acid-level isogenes). [source]


Doubled sugar content in sugarcane plants modified to produce a sucrose isomer

PLANT BIOTECHNOLOGY JOURNAL, Issue 1 2007
Luguang Wu
Summary Sucrose is the feedstock for more than half of the world's fuel ethanol production and a major human food. It is harvested primarily from sugarcane and beet. Despite attempts through conventional and molecular breeding, the stored sugar concentration in elite sugarcane cultivars has not been increased for several decades. Recently, genes have been cloned for bacterial isomerase enzymes that convert sucrose into sugars which are not metabolized by plants, but which are digested by humans, with health benefits over sucrose. We hypothesized that an appropriate sucrose isomerase (SI) expression pattern might simultaneously provide a valuable source of beneficial sugars and overcome the sugar yield ceiling in plants. The introduction of an SI gene tailored for vacuolar compartmentation resulted in sugarcane lines with remarkable increases in total stored sugar levels. The high-value sugar isomaltulose was accumulated in storage tissues without any decrease in stored sucrose concentration, resulting in up to doubled total sugar concentrations in harvested juice. The lines with enhanced sugar accumulation also showed increased photosynthesis, sucrose transport and sink strength. This remarkable step above the former ceiling in stored sugar concentration provides a new perspective into plant source,sink relationships, and has substantial potential for enhanced food and biofuel production. [source]


Development of molecular markers linked to the wheat powdery mildew resistance gene Pm4b and marker validation for molecular breeding

PLANT BREEDING, Issue 2 2008
Y. J. Yi
Abstract Powdery mildew, caused by Blumeria graminis (DC.) E.O. Speer f. sp. tritici, is an important disease in wheat (Triticum aestivum L.). Bulk segregant analysis (BSA) was employed to identify SRAP (sequence-related amplified polymorphism), sequence tagged site (STS) and simple sequence repeat (SSR) markers linked to the Pm4b gene, which confers good resistance to powdery mildew in wheat. Out of 240 SRAP primer combinations tested, primer combinations Me8/Em7 and Me12/Em7 yielded 220-bp and 205-bp band, respectively, each of them associated with Pm4b. STS- 241 also linked to Pm4b with a genetic distance of 4.9 cM. Among the eight SSR markers located on wheat chromosome 2AL, Xgwm382 was found to be polymorphic and linked to Pm4b with a genetic distance of 11.8 cM. Further analysis was carried out using the four markers to investigate marker validation for marker-assisted selection (MAS). The results showed that a combination of the linked markers STS,241, Me8/Em7,220 and Xgwm382 could be used for marker-assisted selection of the resistance gene Pm4b in wheat breeding programmes. [source]


Automation of DNA marker analysis for molecular breeding in crops: practical experience of a plant breeding company

PLANT BREEDING, Issue 4 2007
C. Dayteg
Abstract In modern plant breeding, DNA marker analyses are of increasing importance and, as the methods become more widely adopted, the capacity for high-throughput analyses at low cost is crucial for its practical use. Automation of the analysis processes is a way to meet these requirements. In order to achieve this, while keeping adequate flexibility in the analysis processes, Sval÷f Weibull AB (SW) has developed a fully automated polymerase chain reaction system. It has been evaluated on barley and canola lines and is capable of analysing up to 2200 samples per day at a cost of 0,24 , per analysis for marker-assisted selection and quality control of genetically modified organisms. A detailed description of this system is given, and improvements to the throughput and applications are discussed. [source]


Prospects for molecular breeding of barley

ANNALS OF APPLIED BIOLOGY, Issue 1 2003
W T B THOMAS
Summary Data from UK Recommended List Trials showed that the introduction of new cultivars of spring and winter barley has maintained a significant increase in yield over time, whereas there has been no significant improvement in hot water extract, the major determinant of good malting quality, in either crop. Commercial barley breeding is based upon phenotypic selection, and the introduction of molecular breeding methods must either increase the rate of advance, or offer an improvement in the cost-effectiveness of breeding programmes. Molecular breeding can be applied to either single gene or polygenic characters but is not widely used in commercial barley breeding, other than as a marker for resistance to the Barley Yellow Mosaic Virus complex. There are many reports of potential targets for use in molecular breeding but the few validation studies that have been carried out to date are disappointing. Results from genomics studies are likely to lead to the identification of key candidate genes, which can be associated with economically important characters through co-location on certain chromosomal regions. Associations between candidate gene sequence haplotypes and phenotypic characteristics is expected to identify allelic combinations, which are most frequently observed in successful cultivars, that can be used in molecular breeding of barley on a commercial scale. [source]