Location: Tropical Crops and Germplasm Research2020 Annual Report
1. Efficiently and effectively maintain the safety, genetic integrity, health and viability of priority tropical and subtropical tree fruit, bamboo, and cacao genetic resources and distribute them and associated information worldwide. 1a: Efficiently and effectively safeguard genetic resources. 1b: Back up genetic resource collections. 1c: Distribute pathogen-tested genetic resources. 2. Develop more effective genetic resource maintenance, evaluation, and characterization methods and apply them to priority tropical and subtropical tree fruit, bamboo, and cacao genetic resources. Disseminate evaluation and characterization data via Germplasm Resources Information Network (GRIN)-Global and other data sources. 2a: Characterize and evaluate genetic resources for important horticultural characteristics. 2b: Maintain and enhance access to characterization and evaluation data through GRIN Global, publications, and other databases (MusaNet, ICGD, Bioversity International). 2c: Develop Single nucleotide polymorphisms (SNPs) for cacao and other minor crops within the collections. 3. With other National Plant Germplasm System (NPGS) genebanks and Crop Germplasm Committees, develop, update, document, and implement best management practices and Crop Vulnerability Statements for tropical and subtropical tree fruit, bamboo, and cacao genetic resources and information management.
Plant genetic resources will be efficiently and effectively conserved, backed-up, regenerated, evaluated, and distributed free of diseases. This will be carried out by implementing latest technologies available for field, lab, and greenhouse plant labeling, by maintaining on and off-site backups of critically important germplasm, by field evaluating for important horticultural traits and by indexing/eliminating plant diseases in stock to be distributed. All information associated with plant genetic resources including passport, characterization, and evaluation data will be incorporated into the publicly available Germplasm Resources Information Network (GRIN)-Global database. Development of molecular marker tools is a collaborative effort with other USDA-ARS laboratories and will be used to genotype accessions within the cacao, Annona, sapodilla, Garcinia, sapote and other tropical fruits in the collections, which will aid in the identification of redundancies, discrepancies, and genetic gaps in the collections. In addition, the marker work will complement morphological characterization and stakeholder community input in the development of guidelines to follow for prioritization of future plant introductions. Best management practices and Crop Vulnerability Statements for tropical and subtropical tree fruit, bamboo, and cacao genetic resources and information management will be developed, updated, documented, and implemented.
Progress was made by ARS at Mayaguez, Puerto Rico, on Sub-obj. 1a:Efficiently and Effectively safeguard genetic resources. The following research was conducted by ARS researchers at Mayaguez, Puerto Rico,: 1) As a service oriented project the number of germplasm distributions for FY 2019 amounted to 24 with 38 different accessions with over 1,300 propagules (i.e., seeds, budwood, Tissue culture) were associated with 13 collaborators. Tropical germplasm was distributed in the form of scionwood, rhizomes, corms, seed and fruit), and was made available and distributed to researchers and cooperators locally, 1 state and 2 international organizations; 2) Approximately 600 seedlings of mango have been grown for use as rootstock material for a mango field evaluation; 3) Approximately 112 uncharacterized mango accessions were grafted and leaves sampled and sent for genotyping to ARS, Miami, Florida, to validate identification and determine pedigree and relatedness. 4) Over 120 tissue culture grown banana (Musa spp.) accessions have been received from Bioversity International, France in the last two years. These plants are part of a continued collaborative effort on the verification of genetic integrity of banana genetic resources held in the International Transit Center banana collection in Leuven, Belgium. Many of the plants being field verified have been tissue cultured grown for more than ten years and during this time may have accumulated mutations or propagation mistakes. Plants are being acclimatized and will be field established in FY 20-21 for characterization; 3) Over 240 visits/tours to the station grounds for research, education and relaxation purposes were received during FY 20. Visitors were from 18 states and three foreign countries. Progress was made by ARS researchers at Mayaguez, Puerto Rico, on Sub-obj. 1b: Back up genetic resource collections. The following research was conducted by ARS researchers at Mayaguez, Puerto Rico: 1) Sapodilla field collection has been backed up in the greenhouse area (100%); 2) All Criollos and Ecuadorian cacao clones and about 25% of mamey sapote accessions were backed up in greenhouse. Progress was made by ARS researchers at Mayaguez, Puerto Rico, on Sub-obj. 1c: Distribute pathogen-tested genetic resources. The following research was conducted: 1) Second year of data on fruit resistance/susceptibility to anthracnose, the most important postharvest disease in commercial mango production, has been collected from a segregating maternal half sibling mango population; 2) Twenty accessions of banana that include several hybrids from breeding programs with improved disease resistance and productivity were received from Bioversity International. Plants will be used as Tropical Race 4 (TR4) resistant germplasm for field testing and characterization. TR4 cannot be controlled using fungicides and cannot be eradicated from soil using fumigants; 3) Over 2000 flower pollinations have been completed (out of 4,200) in a bi-parental crossing and selfing scheme to try to characterize a set of ten clonal cacao tree selections for pollen compatibility/incompatibility. In addition, a breeding scheme between disease-resistant Ecuadorian cacao clones and TARS high-yielding clones was initiated. So far over 1250, seedlings from these crosses have been planted in the greenhouse for future field evaluation; 4) A greenhouse disease survey was conducted on 4 different Pitahaya species (Hylocerus undatus, H. polyrhizus, H. guatemalensis and Selenicerus megalanthus) and 22 pitahaya varieties. From this survey, Neoscytalidium dimidiatum was identified in 10 of 22 pitahaya varieties. Pathogenicity tests were conducted to learn if this fungus is pathogenic in Puerto Rico. Four isolates of N. dimidiatum and three pitahaya plants of S. magalanthus were used for the pathogenicity test. All four isolates were pathogenic to pitahaya causing necrotic spots at 8 days after inoculation (DAI), necrotic blotch with chlorotic halo at 15 DAI and stem canker at 20 DAI. This is the first report of N. dimidiatum causing stem canker in Puerto Rico. Progress was made by ARS researchers at Mayaguez, Puerto Rico, on Sub-obj. 2a: Characterize and evaluate genetic resources for important horticultural characteristics. The following research was conducted: 1) A total of 80 cacao clones were characterized and evaluated for pod weight and size, color, number and size of seeds, yield, pod index, organoleptic quality traits, and black pod incidence. In addition, photos of each pod and five seeds are taken. This data is being entered in GRIN-Global; 2) A total of 32 Spanish lime varieties were characterized and evaluated, parameters measured were total weight, number of fruits, size and weight of 20 individual fruits, Brix and acidity. Also, photos of each representative fruit from each variety taken. This data is also being incorporated into the GRIN Global database. This is the second year of data collection; 3) Fruit traits for 30 mango varieties from an old, uncharacterized planting plot dating back to 1930’s and other mango clones on the station grounds have been collected for two years. Parameters measured were size and weight of fruits to include stone and seeds, embryo type (poly or mono embryonic), anthracnose level, fiber content, shape, color, and Brix. Also, photos of fruits from each variety were taken for incorporation into GRIN-Global; 4) In collaboration with ARS researchers in Fort Pierce, Florida, certified disease-free budwood pieces of seven mandarin cultivars were received, grafted onto a common rootstock, increased, grafted again onto three rootstocks and established in August 2015 in a replicated trial at two locations for field evaluation for yield, fruit quality traits, and citrus greening incidence. These accessions have never been evaluated in a replicated experiment. Trees in the lower elevation site were severely defoliated and/or had branches broken by Hurricane Maria winds but had recovered; As of FY 20, determination of citrus greening incidence using enzyme-linked immunosorbent assay (ELISA) tests so far are confirming that the disease is widespread at the lower elevation site (100% contamination) but not a problem at the high-elevation (above 600 meters) site. During FY21, polymerase chain reaction (PCR) tests will be conducted on high elevation trees; 5) Seven disease-resistant cacao accessions grafted onto EET-400 rootstock were established in a replicated experiment for evaluation of yield, pod index, and organoleptic quality traits. These accessions have never been evaluated in a replicated experiment. Trees are now recovered from defoliation caused by Hurricane Maria and data collection initiated again. A year worth of data was lost as a result of hurricane damage; 6) Seven breadfruit accessions grafted onto breadnut rootstock were established in a replicated experiment at two locations in August 2015 for evaluation of yield, disease and insect response, canopy volume, and organoleptic quality traits. These accessions have never been evaluated in a replicated experiment. Trees at both locations are fully recovered from damages (defoliation) caused by Hurricane Maria and evaluation continues; 7) Eight papaya lines developed by collaborators at the University of the Virgin Islands Experiment Station and ARS scientists were established in a replicated experiment at three locations for field evaluation of yield, fruit quality traits, and papaya ringspot virus (PRSV) tolerance. These accessions have never been evaluated in a replicated experiment. Plantings of Year 2 at the three sites were lost because of hurricane damage and the experiment re-established again in FY19; the experiment was completed in FY20; 8) An experiment to evaluate yield and fruit quality traits of eight jaboticaba selections was established in FY19. These accessions have never been evaluated in a replicated experiment. Evaluation continued in FY20. Progress was made on Sub-objective 2b: Maintain and enhance access to characterization and evaluation data through GRIN Global, publications, and other databases. The following research was conducted: 1) Taxonomic nomenclature as well as links provided on QR codes leading to GRIN Global database information were reviewed; 2) Passport information has been updated and descriptors from characterizations as well as voucher images have been loaded into Bioversity databases and GRIN Global for Musa spp., T. cacao and miscellaneous collections; 3) Final data will be collected before the end of the FY20 for 25 Musa spp. accessions in Field Verification (FV) IV as part of a collaborative project with Bioversity International’s Musa International Transit Center. Ten varieties that were in liquid nitrogen (LN) for over 10 years in the international collection are undergoing field verification and characterization for important phenotypic and agronomic traits. The genetic resources evaluated by this project under this subobjective are critical for diversifying horticultural production systems. Results from these experiments help to fill the knowledge gaps on cropping management systems for tropical/subtropical fruit crops by assisting to identify promising germplasm for use by growers. For example, during FY 20, distributions of the nine high-yielding cacao selections released in 2009 were made to farmers in Puerto Rico and the Philippines. Material sent to farmers included about 1000 budwood pieces and over 200 fruits of cacao for rootstock from this collection. Thanks to this effort a completely new cacao industry is being established in Puerto Rico with clones exclusively developed by ARS scientists in Mayaguez, Puerto Rico. These same clones are also being evaluated now in Hawaii and Costa Rica and are in the process of been distributed to AGROSAVIA in Colombia as part of a program of Foreign Agriculture Service (Cacao for Peace)
1. Yield and fruit quality traits of two plantain cultivars grown at two locations in Puerto Rico under black leaf streak disease pressure. Plantains are tropical rhizomatous perennial plants in the Musa spp. genus closely related to bananas. It is an important cash crop and a staple for inhabitants in many parts of the world. ARS researchers at Mayaguez, Puerto Rico, believe leaf streak disease (BLSD) or black Sigatoka, caused by the fungus Pseudocercospora fijiensis, is responsible for significant losses to this crop due to the high susceptibility of the most economically important cultivars. BLSD does not immediately kill plantain plants but, causes severe leaf necrosis which results in reduced photosynthetic area and hence, impacts bunch weight and fruit production. Without cultural and chemical control, yields can be reduced by 20% to 80%, depending on severity. Several promising hybrids such as FHIA-21 have been developed by ARS researchers at Mayaguez, Puerto Rico, and possess BLSD resistance. Their evaluation in multi-site trials is important before commercial adoption by growers. This study by ARS researchers at Mayaguez, Puerto Rico, evaluated ‘FHIA-21’, a BLSD-resistant cultivar, against ‘Maricongo’, a standard commercial cultivar with no BLSD tolerance, at two locations in Puerto Rico on an Ultisol (Corozal site) and Oxisol (Isabela site) soils. This study showed that ‘FHIA-21’ has good resistance against BLSD Sigatoka, produce good yield, and is a viable alternative to current disease susceptible cultivars. However, the threat of ‘FHIA-21’ being affected by the banana streak virus, particularly in periods of stress, should not be discounted and efforts should be made to provide optimum agronomic management to prevent potential stressors.
Irish, B.M., Goenaga, R.J., Montalvo, S., Chaves-Cordoba, B., Van Den Bergh, I. 2019. Host response to black leaf streak and agronomic performance of banana genotypes in Puerto Rico. HortScience. 54(10):1808-1817. https://doi.org/10.21273/HORTSCI13876-19.
Serrato-Diaz, L.M., Aviles-Noriega, A., Soto-Bauzo, A., Rivera-Vargas, L., Goenaga, R.J., Bayman, P. 2019. Botryosphaeriaceae as causal agents of Dieback and Corky Bark in Rambutan and Longan. Plant Disease. 104:105-115.
Goenaga, R.J., Irizarry, H., Jenkins, D.A., Boykin, D.L., Marrero Soto, A.R. 2018. Yield, fruit quality traits and leaf nutrient concentration of sapodilla cv ‘Prolific’ grafted onto 16 rootstocks in Puerto Rico. HortTechnology. 27(4)563-571.
Goenaga, R.J. 2018. Dry matter production and nutrient content of mamey sapote grown on an acid ultisol. Experimental Agriculture. pgs. 1-9. https://doi.org/10.1017/S0014479718000054.
Goenaga, R.J. 2019. Long term productivity of three rambutan cultivars grown in an ultisol soil in Puerto Rico. HortTechnology. 28:863-866.
Mellado-Vazquez, A., Salazar-Garcia, S., Goenaga, R.J., Lopez-Jimenez, A. 2019. Survey of fruit nutrient removal by mango (Mangifera indica L.) cultivars for the export market in various producing regions of Mexico. Terra Latinoamerica. 37:437-447.
Goenaga, R.J., Irish, B.M., Marrero Soto, A.R. 2019. Yield and fruit quality traits of two plantain cultivars grown at two locations in Puerto Rico under black leaf streak disease pressure. HortTechnology. 29(6):958-966. https://doi.org/10.21273/HORTTECH04425-19.
Serrato-Diaz, L.M., Mariño, Y.A., Guadalupe, I., Bayman, P., Goenaga, R.J. 2019. First report of Lasiodiplodia pseudotheobromae and Colletotrichum siamense causing cacao pod rot, and first report of C. tropicale causing cacao pod rot in Puerto Rico. Plant Disease. https://doi.org/10.1094/PDIS-06-19-1333-PDN.
Baligar, V.C., Almeida, A.A., Ahner, D., Pires, J.L., Arevalo-Gardini, Goenaga, R.J., He, Z., Elson, M.K. 2018. Impact of drought on morphological, physiological and nutrient use efficiency of elite cacao genotypes from Bahia-Brazil, Tarapoto-Peru and Puerto Rico-USA. Symposium Proceedings. 87:1-11.