Location: Tropical Crops and Germplasm Research
2023 Annual Report
Objectives
Objective 1: Conduct research to develop genetic resource maintenance, evaluation, or characterization methods and, in alignment with the overall NPGS Plan, apply them to priority banana, cacao, bamboo, coffee, and tropical and subtropical fruit genetic resources to avoid backlogs in plant genetic resource and information management.
Sub-objective 1.A: Evaluate germplasm for important agronomical/horticultural characteristics.
Sub-objective 1.B: Back up germplasm collections and related information.
Sub-objective 1.C: Maintain and disseminate associated information.
Objective 2: Acquire, distribute, and maintain the safety, genetic integrity, health, and viability of priority banana, cacao, bamboo, coffee, and tropical and subtropical fruit genetic resources and associated descriptive information.
Sub-objective 2.A: Effectively acquire and maintain genetic resources.
Sub-Objective 2.B: Distribute pathogen-tested genetic resources.
Sub-objective 2.C: Develop SNPs and assess genetic diversity for cacao and other minor crops within the collections.
Approach
Characterization, evaluation and identification of promising germplasm which may be of use to the tropical fruit industry or improvement programs.
To ensure that no confusion occurs during conservation, regeneration, and distribution, each accession in all the collections is carefully labeled in the screenhouse prior to field planting, identified in field maps as well as labeled during the distribution process. The use of a bar coding system and thermal printers with waterproof and non-photosensitive labels is being implemented for labeling of all plant material and a detailed form with information and instructions for requestors is included with all distributions. Priority tropical genetic resources maintained by TARS consist of 184 of Musa spp., 284 accessions of cacao, 31 of mamey sapote, 23 of sapodilla, 30 of Spanish lime, 13 Annona species, 13 Garcinia species, and 28 genera/species of tropical bamboo. These accessions are clonally propagated and established in field collections. In addition to priority genera, a core backup mango collection consisting of 47 diverse genotypes (primary site is SHRS, Miami, FL) as well as a backup of 64 temperate bamboo accessions (primary site is PGRCU, Griffin, GA) are maintained. Furthermore, a backup core collection of coffee (primary site is PBARC, Hilo, HI will be established during this project life. To limit errors during conservation, regeneration, and distribution, each representative plant within accessions in all the collections, in laboratories, greenhouses, and in the field is carefully labeled. In the field, accessions are identified, with labels, stakes, maps (print and electronic) in databases. The use of a local database, QR code system and thermal printers with waterproof and sunlight resistant labels has been employed and a complete packing list and phytosanitary certificate (if required) is included with all distributions. Embedded information in QR labels contains GRIN database passport and characterization data. As introduction of disease and insect pests is a constant threat to local germplasm collections, standard operating procedures are implemented for visitors. Visitors are informed of the risks and the protocols to follow to avoid introductions, particularly when a visitor originates from a region where disease and insects are prevalent on crops curated at TARS. In addition, signs are clearly posted at both TARS’s research sites warning visitors to follow protocols of registering and being accompanied by TARS employees. Specific acquisition, maintenance and distribution practices for each crop are described below.
Progress Report
This is the first report for the project 6090-21000-061-000D which began in February 2023 and replaces project 6090-21000-057-000D.
Progress was made on Sub-objective 1.A: Evaluate germplasm for important agronomical/horticultural characteristics. The following research was conducted by ARS scientists at Mayaguez, Puerto Rico: 1) A cacao population study was established with crosses made using Ecuadorian selections (male parents) with disease resistance (witches’ broom and frosty pod) and high-yielding TARS selections and involves seedlings obtained from six cacao families; 2) A replicated experiment using 7 breadfruit accessions grafted onto breadnut rootstock established at two locations in August 2015 for evaluation of yield, disease and insect response, canopy volume, and organoleptic quality traits will be completed at the end of the year; 3) In collaboration with ARS researchers in Fort Pierce, Florida, an experiment with 7 mandarin cultivars grafted onto three rootstocks and evaluated for yield, fruit quality traits, and citrus greening (CG) incidence will be completed by the end of 2023; 4) An experiment to evaluate 10 jaboticaba selections for yield, fruit quality traits, and canopy volume was established at Isabela, Puerto Rico; 5) An experiment to evaluate 8 Fiji coconut selections for yield, juice quality traits, disease and insect incidence, and canopy volume was established at Isabela, Puerto Rico; 6) An experiment to evaluate 12 mango selections for yield, fruit quality traits, disease and insect incidence, and canopy volume was established at Isabela, Puerto Rico; 7) an experiment with 4 avocado cultivars grafted onto four Phytophthora root rot (Prr) resistant rootstocks and two seedlings selections was established and will be evaluated for yield, fruit quality traits, and Prr resistance under Isabela conditions; and 8) Eight disease-resistant cacao and two high-yielding selections grafted onto EET-400 rootstock were established in a replicated experiment for evaluation of yield, pod index, organoleptic quality traits, and black pod and virus incidence. These accessions have never been evaluated in a replicated experiment.
Progress was made on Sub-objective 1.B: Back up germplasm collections and related information. The following research was conducted by ARS scientists in Mayaguez, Puerto Rico: 1) Approximately 25 accessions with only one clone per accession were propagated and backed up in a greenhouse; plans are to propagate all accessions with only one tree or plant (vines, rhizomes, etc.) to secure critical germplasm and current germplasm inventory from weather events like storms and hurricanes; 2) Approximately 22 cacao accessions are being propagated by somatic embryogenesis as an attempt to eliminate viruses; and 3) Approximately 700 seedlings of mango, Annona, Sapodilla, Spanish Lime were planted to be used as rootstock for propagation of these species.
Progress was made on Sub-objective 1.C: Maintain and disseminate associated information. The following research was conducted by ARS scientists in Mayaguez, Puerto Rico: 1) Final data (year 5) on yield and fruit quality traits were collected from 30 Spanish lime accessions established in a replicated experiment. Data will be analyzed at the end of 2023 and published; 2) Passport information has been updated and descriptors from characterizations as well as voucher images have been loaded into Bioversity databases (MGIS); 3) Final data was collected for 15 Musa spp. accessions in Field Verification (FV) V as part of a collaborative project with Bioversity International’s Musa International Transit Center; 4) Fifteen accessions of Theobroma cacao have been phenotypically characterized and data is will be entered in GRIN-Global; 5) Taxonomic nomenclature as well as links provided on QR codes leading to GRIN-Global database information were reviewed and all paper labels glued to metal stakes replaced with significantly more permanent labels where information is engraved on metal labels which are nailed to trees. This will continue under this new project.
Progress was made on Sub-objective 2.A: Effectively acquire and maintain genetic resources. The following research was conducted by ARS scientists in Mayaguez, Puerto Rico: 1) Coordination have been made with other repositories (SHRS, PBARC), universities and private industry to acquire new or missing accessions for several crops.
Progress was made on Sub-Objective 2.B: Distribute pathogen-tested genetic resources. The following research was conducted by ARS scientists in Mayaguez, Puerto Rico: 1) Anthracnose is the most important post-harvest disease that affects shelf life in the mango industry. A disease survey was conducted at the USDA-ARS mango germoplasm collection in Isabela. Five species of Colletotrichum in the C. gloeosporioides complex (C. asianum, C. fructicola, C. queenslandicum, C. siamense, and C. tropicale) were found in 18 of the 40 M. indica cultivars evaluated. Colletotrichum asianum was the most predominant species and it caused anthracnose disease on 30 M. indica cultivars. This is the first report of C. asianum causing anthracnose on mango in Puerto Rico; 1) Forty-one M. indica x M. casturi crosses have been inoculated with C. asianum for anthracnose resistance. So far, from 23 crosses evaluated for anthracnose, two have shown tolerance to C. asianum 20 days after inoculation. The remaining 18 crosses are being evaluated for anthracnose response; 2) Coffee fruit rot (CFR) is a major problem worldwide. The literature focuses almost exclusively on fungi in the genus Colletotrichum. In Puerto Rico, this disease is caused by four Colletotrichum species and it is characterized by external sunken lesions and internal rots that eventually causes the grain to become mummified affecting coffee yield and quality. However, recent work by ARS scientists in Mayaguez showed that five Fusarium spp. distributed in four Fusarium species complexes (F. solani, F. fujikuroi, F. lateritium and F. oxysporum species complexes) were pathogens to coffee and they also caused CFR disease in Puerto Rico. Higher diversity of Fusarium spp. was found in the microbiota of the coffee berry borer (CBB) Hypothenemus hampei. Three Fusarium species collected from CBB were pathogens to coffee suggesting that the CBB is the dispersal agent of CFR disease in Puerto Rico. This finding is novel and important because Fusarium species are serious pathogens of many crops and produce numerous mycotoxins and because knowing that CFR is caused by Colletotrichum and Fusarium species is the first step for developing accurate management of this disease in all coffee producing countries. This is the first report of Fusarium spp. causing CFR worldwide and this finding can be used in crop improvement programs seeking to find resistance to CFR; 3) Coffee leaf rust (CLR) caused by fungus Hemileia vastatrix is the most challenging coffee disease worldwide. Fifty physiological races have been reported to exist making difficult its control. Six species of mycoparasites have been found and evaluated under field conditions in Puerto Rico. Simplicillium lanosoniveum, S. lamellicola, Lecanicillium aranearum, L. uredinophilum, Akanthomyces lecanii and Akanthomyces sp. novo were able to reduce incidence of CLR in orchards in Puerto Rico. Field evaluations of these mycoparasites under two different seasons (cold-dry and hot-humid) are being carried out.
Progress was made on Sub-objective 2.C: Develop SNPs and assess genetic diversity for cacao and other minor crops within the collections. The following research was conducted by ARS scientists in Mayaguez, Puerto Rico: 1) Collaborative efforts between several USDA-ARS (SHRS, PBARC and SPCL) laboratories and private industry were undertaken to develop and utilize SNP’s markers to fingerprint cacao, coffee, mango, sapotaceae, and peach palm genetic resources. These efforts will focus on utilizing the fingerprint profiles developed as references for establishing trueness-to-type for clonally propagated germplasm, estimating genetic diversity, and identification of potential gaps in the germplasm collections.
Accomplishments
Review Publications
Goenaga, R.J., Marrero Soto, A.R., Perez, D.O. 2022. Growth and nutrient concentration of lychee grown on an acid ultisol. HortTechnology. 32:6. https://doi.org/10.21273/HORTTECH05120-22.
Adegbola, R.O., Keith, C.V., Gutierrez, O.A., Goenaga, R.J., Brown, J.K. 2022. A previously undescribed polerovirus (solemoviridae) infecting theobroma cacao germplasm. Plant Disease. 107(3). https://doi.org/10.1094/PDIS-06-22-1449-PDN.
Yaw, T.A., Merem, E.C., Namwamba, J.B., Annan, J.B., Ayala Silva, T., Asare-Ansah, A.B., Ning, Z., Oppong, J., Loh, P., Frimpong, D.B., Owusu, F., Mjema, J.E., Okwemba, R., Mwakimi, O.S., Petja, B.M., Akinrinwoye, C.O., Mcclendon-Peralta, J., Mosby, H.J. 2021. Land resource areas and spatial analysis of potential location of bioenergy crops production in Mississippi. Journal of Sustainable Bioenergy Systems (JSBS). 11:187-214. https://doi.org/10.4236/jsbs.2021.114013.
