|Dardick, Christopher - Chris|
Submitted to: Plant Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2011
Publication Date: 2/1/2012
Citation: Sajer, O., Scorza, R., Abbott, A., Horn, R., Dardick, C.D. 2012. Development of sequence-tagged site markers linked to the pillar growth type in peach (Prunus persica). Plant Breeding. 131:186-192. Interpretive Summary: The productivity of peach orchards is low in comparison to other fruit crops. This reduces income for farmers and limits the supply of peaches in the market. Productive orchards are vital to a healthy fruit industry, large, and small growers. Fruit crops such as apple have increased productivity and orchard efficiency through the use of new tree growth forms and dwarfing rootstocks. A number of potentially useful peach growth forms naturally exist, including the columnar or “pillar” form. Breeding pillar and the less extreme upright growing peach tree is limited in efficiency due to the difficulty in the breeding program of selecting which young seedling trees will have the desired growth form. It can take 3 years or more to determine the ultimate growth form of trees. We have found a molecular marker, a specific piece of DNA that is closely associated with the gene for columnar and upright growth. By checking young seedling for this gene, the desired growth form can be selected very rapidly and only the desired trees planted in the field for fruit evaluation. The use of this marker will reduce the costs of peach breeding and make the breeding process more efficient. Providing new columnar and upright peaches for growers can increase peach orchard productivity and efficiency and increase the availability of peaches in the market.
Technical Abstract: In peach [Prunus persica (L.) Batsch], trees showing columnar [also termed pillar or broomy] growth habit are of interest for high density production systems. While the selection of the columnar homozygote (pillar) phenotype (brbr) can be carried out prior to field planting, the intermediate heterozygous upright (UP) phenotype is difficult to distinguish from standard (ST) trees until they are quite large in the field. Application of marker-assisted selection would be helpful in establishing more efficient breeding programs developing pillar and UP growth forms. Twenty-seven AFLP-markers and three SSR-markers identified by bulked segregate analyses mapped together with the br gene on linkage group 2 of the Prunus reference map. The linkage group covers 92.8 cM. The AFLP-marker ETGM61_291R mapped with 4.8 cM to the br gene on one side, the closest AFLP-markers ETAM56_267A, ECAM61_426A, and ETAM48_279A with 3.8 cM on the other side. These four AFLP-markers were cloned and sequenced for conversion into STS-markers for easier use in marker-assisted breeding programs. Primer combinations derived from ETGM61_291R and ETAM48_279A are now available that can distinguish pillar and ST genotypes as well as heterozygous UP plants.