Location: Tropical Plant Genetic Resources and Disease Research
Project Number: 2040-21000-019-000-D
Project Type: In-House Appropriated
Start Date: May 31, 2023
End Date: May 30, 2028
Objective:
Hawaii is one of the most geographically isolated areas in the world. Although this geographic isolation has been beneficial in the past, increased global transportation and commerce have provided a pathway for introducing invasive pests and pathogens. This isolation also results in higher transportation costs for importing essential farm supplies such as fertilizer, pesticides, and other supplies and exporting goods to the continental U.S. and global market. In sub-tropical and tropical growing climates, plant diseases flourish in warm, humid environments. Understanding disease development is the first step to effective control methods, either through chemical control or enhanced techniques for breeding and deploying resistant crops. Objective 1 of this plan aims to develop methods for early detection, mitigation, and management of diseases in economically important crops in Hawaii. It focuses on addressing a potentially destructive disease in coffee.
Objective 1: Generate new knowledge of disease etiology and the epidemiology of emerging invasive species for tropical crops.Sub-objective 1.A: Identify and characterize emerging pathogens attacking important sub-tropical and tropical crops including cacao, mango, and avocado. Sub-objective 1.B: Identify and characterize emerging Colletotrichum spp. attacking coffee.
Objective 2 of this proposal addresses the need to develop and screen new coffee varieties for disease resistance, productivity, and cupping quality for long-term sustainable production. In the meantime, cultural control methods and pesticides must be investigated for short-term solutions to combat these pests and pathogens.
Objective 2: Develop or characterize new genotypes, sustainable management strategies, or combined approaches to control pests and diseases for tropical crops. Sub-objective 2.A: Develop disease management strategies for coffee leaf rust control. Sub-objective 2.B: Evaluate coffee varieties for resistance to coffee leaf rust, root-knot nematode, horticultural characteristics, and cupping quality from World Coffee Research (WCR), Hawaii Agriculture Research Center (HARC), and other coffee sources.
Objective 3 utilizes comparative transcriptome profiling of nematode infected roots to identify genes in coffee that trigger resistance to root-knot nematode. Furthermore, objective 4 implements the use of these genes for nematode resistance in bananas and anthuriums.
Objective 3: Increase genomic information for important tropical crops to accelerate gene discovery and germplasm improvement. Sub-objective 3.A: Identify genes that are associated with resistance to root-knot nematodes in coffee. Sub-objective 3.B: Identify genes for product quality traits in tropical crops.
Objective 4: Improve disease resistance and value-added traits in tropical crops using conventional breeding and biotechnology. Sub-objective 4.A: Utilize RNAi technology targeting novel effector genes to control burrowing nematode, Radopholus similis. Sub-objective 4.B: Develop papaya lines with universal resistance to PRSV.
Approach:
Novel and sustainable strategies for controlling pathogens and pests are needed to decrease production costs while maintaining high product quality. In order to receive premium prices, these specialty products must maintain high quality both in appearance and taste. The goals of this research are to 1) develop methods for early detection and characterization of plant diseases; 2) develop sustainable management strategies for coffee leaf rust and new rust-resistant varieties; 3) develop genomic tools for nematode resistance, novel color, and prevention of browning; and 4) develop new genotypes for resistance to nematodes and papayas resistant to Papaya ringspot virus. The specific goals and approaches for each objective are noted below.
Objective 1: Develop a system for early and accurate identification of emerging plant pathogens as a crucial first step to limiting the spread, reducing their economic impact, and preventing future disease outbreaks. Sub-objective 1A: Develop a system for early and accurate identification of emerging plant pathogens as a crucial first step to limiting the spread, reducing their economic impact, and preventing future disease outbreaks. Sub-objective 1B: The species of Colletotrichum infecting coffee in Hawaii can be genetically classified and sources of resistance can be identified among coffee accessions.
Objective 2: Develop or characterize new genotypes, sustainable management strategies, or combined approaches to control pests and diseases for tropical crops. Sub-objective 2A: Determine which fungicides are most effective in controlling CLR and optimize the strategy and timing for rotation of products so that maximum control can be achieved and fungicide resistance and copper toxicity can be avoided.. Sub-objective 2B: Evaluate coffee varieties for resistance to coffee leaf rust, root-knot nematode, horticultural characteristics, and cupping quality from World Coffee Research (WCR), Hawaii Agriculture Research Center (HARC), and other coffee sources.
Objective 3: Increase genomic information for important tropical crops to accelerate gene discovery and germplasm improvement. Sub-objective 3A: Identify resistance genes against M. konaensis from nematode-resistant coffee cultivars and develop molecular markers to increase the efficiency of nematode resistance screening for coffee breeding programs. Sub-objective 3B: Develop a reference genome and perform RNA sequencing to provide information on metabolic genes involved in quality traits such as color and browning for cultivar improvement in anthurium.
Objective 4: Improve disease resistance and value-added traits in tropical crops using conventional breeding and biotechnology. Sub-objective 4A: Burrowing nematode reproduction will be suppressed on roots expressing dsRNA from nematode effector genes. Sub-objective 4B: Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 or Cas9/ sub genomic RNA (sgRNA) directed mutation of an endogenous papaya gene eIF4E or eIF(iso)4E gene will confer broad viral resistance and result in commercial papaya cultivars with universal resistance to PRSV and related viruses.
