2010 Annual Report
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.