Location: Subtropical Horticulture Research
Project Number: 6038-21000-026-014-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jun 15, 2024
End Date: Jun 14, 2028
Objective:
The USDA mandate to produce quality food at a lower environmental impact will require developing sustainable crop varieties that grow sustainably, are adapted to modern orchard management practices and enriched in nutrients. Developing such varieties are heavily dependent on availability of genetically diverse germplasm that is preserved and well characterized. The germplasm resources of tropical and subtropical fruits, and sugarcanes and related grasses maintained at the Subtropical Horticulture Research Station (SHRS) in Miami, FL provide a foundation for developing climate-resilient, high-yielding and nutrient-rich crop and fruit varieties. More than 9,00 Sugarcane, 165 avocados and 250 mango accessions are maintained at USDA-ARS-SHRS, Miami, FL. Traditionally, most crops are stored as desiccated seeds in genebanks. Seeds of many tropical fruit crops such as avocado and mangos are desiccation-sensitive and recalcitrant to long-term storage. (Sub)tropical crops are highly heterozygous, which, because of genome reshuffling during gametogenesis and sexual reproduction, results in transgressively segregating progeny that are not true-to-type and loose the clonal identify of the original adapted elite variety. These crops are preserved in situ in the field by clonal propagation. However, due to biotic and extreme weather threats, tissue culture and cryopreservation have been promoted similar to bananas and other crops. Towards this goal, this agreement will accomplish: 1) establishing tissue culture methods for sugarcane, avocado, mango, palm and cacao accessions, 2) Best-management practices for tissue culture routine and distribution through GRIN-global. 3) deliver 50 sugarcane, 5 avocado and 5 mango accessions in tissue culture to USDA, Miami, Florida.
The primary objective of this cooperative agreement is to establish tissue culture methods and protocols for sugarcanes, mangos, avocados, palm, and cacao at the USDA/ARS Subtropical Horticulture Research Station (SHRS) located in Miami, FL, which is an integral part of the National Plant Germplasm System (NPGS). The proposed tissue-cultured germplasm material and associated protocols generated through this collaboration will serve as the basis for preserving the germplasm at the USDA facility in Miami and other designated locations. This collaboration is expected to lay the foundation for the long-term preservation of valuable germplasm, and it is anticipated that the resulting protocols will be helpful resources for future research in the field.
Approach:
We will prioritize development and tissue culturing methods for sugarcane first, followed by mango, avocados, and others, to create a robust in vitro collection of healthy and disease-free accessions. We aim to maintain healthy and regenerative germplasm with the fewest minor subculturing cycles for the longest possible time. We will optimize media and growth conditions for specific accessions, evaluate various growth-suppressive conditions, and establish shoot proliferative cultures for six avocado accessions and five elite mango cultivars for cryopreservation testing.
We will prioritize methods of development and tissue culturing for sugarcanes, followed by mangos and avocados. This sub-objective aims to establish a robust in vitro collection of avocado, mango, and sugarcane accessions to ensure their safety, maintenance, and distribution in a disease-free, healthy state. With the fewest subculturing cycles, we aim to maintain healthy and regenerative germplasm for as long as possible. While existing literature provides a foundation with tissue culture methods and media compositions for avocados, mangos, sugarcanes, and other tropical fruit crops, our research is novel as it aims to optimize media and growth conditions for specific accessions due to genetic variability. Variability in shoot and root induction has been reported in response to different media, growth conditions, and types of explants for avocado, mango, and sugarcanes. Our strategy is to first try published media compositions and conduct optimization research for unsuccessful results. To achieve our research goals, we will amend various growth media, such as Murashige & Skoog (MS), B5 medium, Woody Plant Medium (WPM), and others, with different combinations of auxins, cytokinins, and other growth regulators, as well as additives such as activated charcoal. We will also evaluate various growth-suppressive conditions, such as cold temperatures, low or different wavelength lighting, and growth regulators, to find optimal storage conditions that result in longer storage time with fewer sub-cultures and less frequent cycling between soil and tissue culture. We will establish shoot proliferative cultures for six prioritized avocado accessions representing Mexican, Guatemalan, and West Indian races and hybrids. Summarized information as below:
1. We will start the project with sugarcane cultures, and then expand to mangoes.
2. Time-frame for sugarcane cultures is about 12 months, for mangos 18-20 months.
3. Approximate budget the project would be around $45,000.
4. We had considered hiring a pos-doc and/or OPS. We do have an undergraduate student who has worked in our lab and is qualified to do the work as an OPS employee. He is graduating this semester and would be available by May. We are meeting with him this afternoon to discuss it.
5. For the future, we will include avocado cultures and other fruits, ornamental and cacao as need arise for the SHRS and availability of resources.
