Application of new technologies to expedite cleaning of new accessions for use in Florida

Application of new technologies to expedite cleaning of new accessions for use in Florida

Report Date: 04/04/2017
Project: 873
Category:

The objective of this project is to use “new technologies” to accelerate the elimination of graft transmissible pathogens in germplasm accessions for use in citrus breeding in Florida. These “new technologies” include the application of cryotherapy (freezing the buds in liquid nitrogen followed by recovery of the treated buds by grafting onto seedling rootstocks) and the use of “mini-plant-indexing” which allows the biological indexing for graft transmissible pathogens using young seedling indicator plants, 60-75 days old seedlings. During the current reporting period we continue to maintain/evaluate thirty scion selections (five replicate plants of each) that had been cryo-treated at the National Center for Genetic Resources Preservation (NCGRP) in Fort Collins. One hundred fifty, budeyes of CLas-infected selection USDA 1-23-130 were sent to the NCGRP in Ft. Collins. 100 buds were processed and 50 buds were recovered following cryo-treatment and grafted onto seedling rootstock (Carrizo). In the previous report we identified nine promising scion selections that were chosen for cryopreservation. All nine of these selections have been placed into cryopreservation at the Germplasm Preservation Lab. Plants recovered from cryopreservation will be sent to Ft. Pierce for evaluation and pathogen testing. Our permit expired during the last reporting period and must be renewed prior to return of plant material to Florida. During the current reporting period four additional promising scion selections were identified in the USDA citrus project. These selections will be cryopreserved within the next few weeks. To date, a total of 16 USDA advance scion selections that have been cryo-preserved. These selections can otherwise only be maintained as whole plants. Currently, greenhouse space is at a premium for HLB research and therefore, use of greenhouse space for germplasm preservation has become minimal. To maintain advanced selections in the field means likely infection with Liberibacter, and subsequent HLB. The cryopreservation process is proving to be an efficient means to preserve citrus germplasm.


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