Marker Assisted Selection Biotechnology in Action

Traditional Tree Breeding  Selection of trees is based on visible traits (phenotypes)  Grafts or seeds are taken from the selected trees  Crossbreed the selections  Perform progeny testing  Select the best  Repeat  Time consuming and results are sporadic

Marker Assisted Selection (MAS) Using DNA markers to assist in the selection of trees for breeding, testing, or production Using DNA markers to assist in the selection of trees for breeding, testing, or production

DNA Made up of nitrogen bases; adenine (A); cytosine (C); guanine (G); thymine (T) Made up of nitrogen bases; adenine (A); cytosine (C); guanine (G); thymine (T) Proteins are built based on the sequence of the nitrogen bases Proteins are built based on the sequence of the nitrogen bases AGTCAGTC represents different protein than TAGTAGCTA AGTCAGTC represents different protein than TAGTAGCTA Small fraction of DNA code for proteins Small fraction of DNA code for proteins Most DNA represents non-coding sequences Most DNA represents non-coding sequences Complete sequence is called a genome Complete sequence is called a genome

MAS Markers are not normal genes Markers are not normal genes Seldom have biological effect Seldom have biological effect Can be thought of as landmarks Can be thought of as landmarks Identifiable DNA sequence Identifiable DNA sequence Found at specific location on genome Found at specific location on genome Follow standard laws of inheritance Follow standard laws of inheritance

MAS (cont.) Markers require DNA evaluation Markers require DNA evaluation Different kinds of markers exist Different kinds of markers exist RFLPs; SNPs RFLPs; SNPs All types vary in technical requirements amount of time, money, and labor needed All types vary in technical requirements amount of time, money, and labor needed Information provided by each type of marker is different Information provided by each type of marker is different

Utilizing MAS Many traits are genetically complex, involve many genes Many traits are genetically complex, involve many genes Selecting individuals from a population based solely on phenotype would not produce desired offspring Selecting individuals from a population based solely on phenotype would not produce desired offspring Markers have been found that are always associated with the desirable phenotype Markers have been found that are always associated with the desirable phenotype Example: Frost resistance in trees is a genetically complex trait Example: Frost resistance in trees is a genetically complex trait Markers have been used to identify off spring of parent trees with frost resistance. Markers have been used to identify off spring of parent trees with frost resistance.

MAS Frost Resistance DNA is extracted from selected trees DNA is extracted from selected trees Electrophoresis is used to identify individuals with desired marker Electrophoresis is used to identify individuals with desired marker Marker indicates presence of frost resistance. Marker indicates presence of frost resistance.

MAS Analysis Marker for frost resistance Individuals 1, 3, 4 and 6 have the marker for frost resistance in their genotype. Individuals 2, 5 and 7 do not have the frost resistance marker.

Future of MAS Has the future to reduce the time it takes to create new seed plantation. Has the future to reduce the time it takes to create new seed plantation. Could produce a “better” tree in years instead or decades Could produce a “better” tree in years instead or decades Only major species of trees will be utilized Only major species of trees will be utilized Not enough studies to determine if process is cost effective on a commercial basis Not enough studies to determine if process is cost effective on a commercial basis May be utilized to save trees such as the American Chestnut May be utilized to save trees such as the American Chestnut