Page Banner

United States Department of Agriculture

Agricultural Research Service


Location: Tropical Plant Genetic Resources and Disease Research

2010 Annual Report

1a. Objectives (from AD-416)
Produce new knowledge of molecular biology, genetics, and crop traits of selected fruit, vegetable, and ornamental crops grown in Hawaii, and preserve selected sugarcane germplasm that is more suitable for growing in Hawaii. Use genetic engineering approaches to enhance the disease resistance of ornamentals such as anthurium and orchids. Develop improved germplasm for the nation’s sugarcane industry through increased biomass and/or sugar, increased resistance to abiotic stress, pathogens, and pests. Evaluate the horticultural characteristics of Jatropha, kukui, and other tropical crops for their potential as biofuel when grown in Hawaii. Assess the potential commercial application and the potential environmental and biosafety risks of transgenic plants that are developed.

1b. Approach (from AD-416)
Continue tissue culture multiplication of transgenic anthurium lines for subsequent screening by PBARC for bacterial and nematode resistance. Use HARC land to grow selected sugarcane lines that cannot be consistently maintained at the sugarcane clonal repository in Miami, Florida. Cross lines of material selected by the national sugarcane centers and distribute seeds from these crosses for their environmental selection for production of sugar and biomass. Cross lines of target crops to produce mapping populations for developing molecular markers associated with important agronomic traits. Use laboratory and field based approaches to evaluate and develop value added products from potential tropical biofuel crops, such as sugarcane, Jatropha, and kukui. Work with PBARC to develop risk mitigating gene constructs that consists of short-linked segments of genes or computer-generated consensus sequences derived from sequences of a family of genes or gene segments, and use them to develop transgenic plants, such as papaya, for resistance to pathogens and enhanced agronomic traits. Documents SCA with Hawaii Agriculture Research Center (HARC); formerly 5320-21000-011-01S (5/18/087).

3. Progress Report
The agreement was established in support of the Objective of the in-house project, the goal to develop new knowledge about the genetics, genomics, and transgenics of selected tropical crops. Continued to exploit Hawaii’s high level of sugarcane flowering to assist ARS sugarcane breeding programs in Houma, LA and Canal Point, FL. A set of 14 leading, but reluctant-flowering, US varieties were used for hybrid seed production in Hawaii. All 14 varieties flowered and were used in reciprocal crosses to produce spikelet “fuzz” that should contain sexual seed. Seedling germination from exported fuzz was poor indicating either poor seed set, or that the seed had been killed by sanitation treatment of the fuzz. Care will be taken this coming year to export good seed by assuring the parental lines are not stressed when set up for crossing and to implement a quality check of seed germination from fuzz prior to and following sanitation treatments. PCR quantification of sugarcane yellow leaf syndrome virus indicated that there may be more than one strain in Hawaii with differential capacity to elicit disease. Sequencing of papaya BAC clones was completed. Forty plants carrying reproduction-related mutations, such as a male plants with inflorescences resembling those of hermaphrodites, male plants with aborted flowers or with short or less branched peduncles, female plants with long peduncles or producing fruits with altered shapes and sizes were identified among the first group of plants. These mutants are being saved through crossing and/or tissue culture. Preparations of all EMS-treated plants have been made for TILLING analysis. Callus cultures were initiated for the three papaya cultivars Kapoho, Sunrise, and Kamiya in preparation for validating sex determination gene candidates via genetic complementation. Eight molecular markers associated with resistance or tolerance of papaya to its major pathogen, Phytophthora palmivora were identified by screening F2 progeny of a cross between tolerant ‘Kamiya’ and susceptible ‘SunUp’. Seven of the eight makers were sequenced and the data blasted against the papaya genome database to identify potential resistance genes. Proteomic profiles of ‘Kamia’ and ‘Sunup’ roots after inoculation with P. palmivora were used to identify proteins associated with papaya response to this rot pathogen and to predict the responsible genes. Twenty-nine differentially expressed proteins were identified and their roles in papaya defense to pathogens are being studied. F1 populations of pineapple cultivars F153 (Smooth Cayenne) and Hana64 (spiny) were planted for mapping of genes associated with leaf spines. Crosses were made to generate F2 populations. Transcriptome sequencing of the two parents was completed. The sequences will be analyzed to develop SSR and SNP markers that will be used for mapping. The project is monitored by meetings, on-site visits, progress reporting, and telephone and email communications.

4. Accomplishments

Last Modified: 2/23/2016
Footer Content Back to Top of Page