Accelerated and targeted evolution. Application of genetics principles to crop improvement. Systematic procedures used to improve trait phenotypes by crossing and selection, directed manipulation of the genotype at the DNA sequence level, and introduction of new genes.
Modern plant breeding is an application of genetic principles. Crop improvement is a cyclic process of identifying new variation, crossing, selection, and fixing favorable traits. Fundamentally breeding is evolution by artificial selection. Agricultural food production Each year humans re-create the food supply that feeds 6. Projected population increase under different assumptions of reproduction and mortality 4.
Projections We need to make as much progress in production efficiency in the next 30 years as we have made in the previous 12, We need to double food production by The success of plant breeding Increases in yield are derived both from improved varieties and from improved management.
In vegetable crops, research suggests about a split between genetic gain and gain attributed to management. Genetic gain in grain yield of 75 Kg ha-1 yr-1 for corn can be attributed to breeding. Crop Science. Green revolution varieties have increased yields 2 to 3 fold in many developing nations Knight, The crisis in plant breeding Public sector research into classical crop breeding is declining dramatically Knight, Number of students trained in plant breeding is decreasing.
Shift from public to commercial sector than at Universities or Government research organizations. Easy traits to manipulate via GMO techniques are single gene these are also easily manipulated using conventional breeding. Conventional breeding can manipulate multiple traits simultaneously Conventional breeding can manipulate genetically complex quantitative traits Traits that are influenced by the environment Traits that are conditioned by multiple genes Selection on phenotype is a powerful approach to bring about directed changes.
Robust but can be slow; requires that genetic variation exist for the trait of interest Complex genotype x environment systems that agriculture operates under means that methodology of evaluation will always be important. The traits that are most easily altered with transgenics are easily manipulated with traditional breedingwith some key exceptions Transgenic Single genes Anti-sense Expanded gene pool.
The Future: Boost the power of conventional breeding by marrying it to genomic and other molecular-genetic techniques Build on strength of incumbent strategy e. Augment trait-based selection with knowledge-based approach that targets selection at the level of DNA sequence variation Robustness will be determined by rigor of marker-trait association.
Concerted effort to break with proprietary approach to intellectual property. Open-source crop-improvement. The challenge of scale - computational High-throughput Pipelines Standardization Controlled vocabulary. The results of Structural Genomics gives us many new tools to improve crops through map-based breeding.
There is a broader context to the methodology e. When considering the handling of undesirable variation it is inevitable that the discussion will centre on agricultural field trials, since modern experimental technique was initiated and has reached its greatest elaboration in this realm K.
More research is needed for knowledge based approaches i genetic architecture of the trait combinations we seek to manipulate ii the nature of the genetic changes that were brought about by phenotypic selection anthropological genetics iii the power that can be attained in conventional breeding strategies iv the power that can be obtained by molecular breeding strategies v the limits that will be faced in using genetics conventional or molecular to improve crops.
Clustering genes into functional groups requires measuring gene expression under many environmental conditions and treatments. What is the most appropriate breeding technology? How can new technologies enhance the all ready proven techniques of traditional breeding without diverting resources?
Biotechnology advocates argue that the development of new varieties through transformation is more precise than introducing traits from wild species. Is there a factual basis for this argument? How important are trans-genes to the future of crop improvement?
We can reconsider conventional wisdom There is no way to measure the value [of] individual loci of a polygenic character. Nevertheless, an understanding of their role in determining the population mean is helpful for evaluating the impact of selection on population performance. Fehr, pg. Fundamentals of genetics Keep in mind how reproduction, mating scheme, and selection unit affects your crop with respect to segregation ratios and levels of heterozygosity for genes, individuals, and populations.
Goals of Course: Grounding in conventional techniques Methods used for inbreeding and outbreeding species Methods for maximizing or minimizing recombination and why we might want to do this Knowledge of new technologies GMO Integration of genome sequence and related genomics technologies. Open navigation menu. Domestication, Patterns of evolution in crop plants, Centres of origin, Plant introduction, History of plant introduction, Plant introduction agencies in India,.
The procedure of plant introduction, Germplasm collections. Exploration, Purpose of plant introduction,. Some important achievements of plant introduction, Merits of plant introduction, Demerits of plant introduction, Summary. Modes of reproduction, Asexual reproduction, Sexual reproduction, Anthesis, Modes of pollination Self-pollination Cross-pollination. This implies evolution from a tetraploid ancestor. Arabidopsis thaliana: Chromosomes 6. Mitochondrial DNA The mitochondrial genome in plant cells is the result of duplication events.
Norman Borlaug - Molecular markers linked to specific phenotypic traits Quantitative Trait Loci are now being applied to screen for varieties with the desired traits prior to selection of their genetic material for incorporation into breeding programs. The solution to this problem lies in backcrossing or in genetic modification using horizontal gene transfer into inbred lines. What are the three forces which drive the evolution of the genome? Green indicated pollen and red indicates ovules.
Ideally, two markers will be more accurate at predicting the presence or absence of the trait as compared to a single marker. The distance between the marker and the trait should not be in excess of 5 cM. Marker assisted evaluation of breeding material. Marker assisted backcrossing. Marker assisted pyramiding. Early generation MAS. Combined MAS.
Elite variety should technically exhibit traits from all the 4 parents. MAS results are not published. Reliability and accuracy. Insufficient linkage between marker and QTL. Limited markers and limited polymorphism. Effects of genetic background. QTLs and environmental effects. High cost of MAS. Application gap. Knowledge gap. These puts molecular markers beyond the reach of small breeders.
This may be the result of the need to protect Intellectual Property IP. Gene pyramiding. Efficiency of gene pyramiding. Qualitative improvement through pyramiding. Polygenic trait improvement by gene pyramiding.
Molecular Breeding The objective of molecular breeding is to develop plant varieties with desired traits. Molecular Breeding Strategies Introgression of specific trait encoding genes Steps in Molecular Breeding 1. Characterization of the pathway. Identifying genes involved in the pathway.
Gene isolation 5.
0コメント