Project Number: 8080-21000-029-05-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Dec 15, 2014
End Date: Nov 30, 2019
Apple and peach have tremendous genetic diversity with respect to architectural types, offering unique opportunities to dissect the underlying mechanism that leads to varying tree forms in perennial woody species. The availability of whole genome sequences along with established genetics and phenotypic variants makes these systems ideally suited to dissect the gene networks that underlie tree architecture. Of particular interest here, are the availability of forms with alterations in branch angle and the directional growth of lateral meristems. These include columnar or pillar types in which lateral meristems maintain an overall vertical, upward orientation and weeping types in which the lateral mersitems orient downward. The genomic bases for variations in this fundamental development trait are unknown but are undoubtedly influenced by environmental factors such as the plant's response to gravity and light. Here, we aim to establish the genetic networks associated with branch angle and lateral meristem orientation as well as their environmental influences. This will be accomplished through a series of genomic-scale studies and by identifying cooperating partners of recently identified genes that are known to control branch angle in peach and apple.
Transcriptome profiling techniques will be used to study branch growth in peach and apple germplasm that will include standard growth, pillar/columnar, and weeping varieties. Gene expression will be monitored under various conditions such as hormone treatment, pruning, and mechanical manipulations. Tree phenotypes will be assessed using a whole tree imaging technology that will allow three dimensional imaging and data gathering. Genes underlying key phenotypes will be identified using a novel sequence-based mapping strategy called pnomes that enables rapid mapping and candidate gene identification. Yeast two-hybrid screens will be utilized to identify interaction partners of proteins known to play key roles in branch growth.