Project Number: 6631-21000-016-00
Project Type: Appropriated

Start Date: Dec 17, 2003
End Date: Oct 31, 2008

Objective:
The primary goals for this project are to conserve, collect, evaluate, and distribute germplasm and associated information for subtropical/tropical fruit, sugarcane, and Tripsacum. A secondary goal is to investigate the genetic basis of important horticultural traits such as disease resistance and to select improved germplasm. Molecular markers have been developed for genetic diversity analysis and for the production of molecular genetic linkage maps. Families of avocado, mango, and jackfruit have been produced that should allow the mapping of Quantitative Trait Loci (QTL) involved with disease resistance, fruit quality, and yield. A candidate gene approach (CGA) is also being used to find genes involved with disease resistance and for control of flowering.

Approach:
Maintain healthy field collections of current accessions of tropical/subtropical fruit trees and grasses. We recognize that the genetic diversity available in tropical fruit species is not fully represented in the current collections. Significant loss of biodiversity and increasing difficulty in collecting germplasm in tropical countries makes it imperative that new accessions be collected as quickly as possible. Implement improved horticultural practices to ensure the longevity of current collections by re-propagating old clones on new rootstocks in new fields. Add new accessions as they become available from foreign collaborators and breeding programs. Because Most of the species and location priorities for collection have been established, it is essential that we support international collecting expeditions with appropriate benefit sharing. After quarantine requirements have been satisfied, the new accessions will be maintained in field plantings. Backup core collections have been established in Mayaguez, Puerto Rico or Hilo, Hawaii. Adequate daily maintenance and periodic replanting of the sugarcane and Tripsacum collection is required to maintain these genetic resources, some 1,800 accessions, as healthy clones. Clones in the sugarcane collection need to be tested to determine if they are infected with Clavibacter xyli subsp. syli, or SCYLV.