Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611
Performing Department
Gulf Coast Research and Education Center
Non Technical Summary
The University of Florida Tomato Breeding program has been the foundation of cultivar development for the state, either directly by the release of new cultivars or indirectly by providing breeding lines and other germplasm to private breeders. Continued breeding progress is essential to sustain the tomato industry. Research and breeding activities strive to develop commercially acceptable cultivars with high yield potential, reliable fruit set, resistance to multiple diseases, improved flavor and quality, and mechanical harvestability.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
To develop tomato cultivars and germplasm with:Resistance to fungal, bacterial and viral diseases and to insect and nematode pestsImproved fruit qualityImproved fruit setCompact growth habit
Project Methods
To develop tomato cultivars and germplasm with disease and pest resistance:Fungal diseases. Resistance to Fusarium wilt race 3 will be increasingly emphasized. A reduced I-3 introgression has been developed, and testing has confirmed that this introgression is free of negative effects previously associated with I-3 (Hutton, unpublished data). This introgression will be incorporated into advanced lines and also combined with other sources of Fusarium wilt race 3 resistance. Marker assisted selection (MAS) is used for advancingI-3as well as the Frl gene for Fusarium crown and root rot resistance. Resistance to both diseases is confirmed in advanced selections an in hybrids using seedling disease assays. Target spot resistance is being advanced from several resistant accessions identified from S. cheesmaniae, S. galapagense, and S. pimpinellifolium. Seedling assays are used to identify resistant plants for use in a modified backcrossing approach, and field testing will be done to verify resistance in advanced backcross materials. Studies are underway to determine the inheritance of resistance and to identify molecular markers linked to the resistance genes for facilitating MAS for variety development. Late blight resistance is emphasized in the program to a small degree and is accomplished by selection for the Ph-2 and Ph-3 genes using MAS. Resistance in promising inbreds and hybrids will be confirmed using seedling disease screens and/or by mature plant screens in the field in collaboration with researchers in North Carolina.Bacterial Diseases. Bacterial spot resistance focuses on pyramiding multiple QTL from sources including H7998, H7981 and PI 128216. Efforts also seek to utilize non-blighting (NB) resistance, where plants maintain healthy foliage despite bacterial spot infection. A major source of NB is Fla. 630, and populations with NB resistance from Fla. 630 are currently being used for QTL mapping. Bacterial wilt resistance breeding is based on Fla. 8109 and other inbreds with resistance derived from H7997. Goals include elucidation of all major QTLs in these sources that confer resistance. Two recombinant inbred line (RIL) populations are being used for these QTL mapping studies, which involves multiple large field experiments and genome-wide marker analyses.Virus diseases. For TYLCV resistance, the major virus threat in Florida, MAS is being used to incorporate the Ty-1/3 and Ty-6 genes into advanced breeding line backgrounds. These resistance genes are also being combined with bacterial spot resistance, heat-tolerance, and other characteristics to provide Florida growers with reliable production. Efforts are also underway to generate near-isogenic lines that will allow testing of all known Ty genes, both singly and in various combinations, within several individual backgrounds. Such resources will facilitate world-wide testing to better understand which genes are most effective for managing diverse begomoviruses which are present around the world now and could eventually emerge in Florida. MAS is used to advance the Sw-5 or the Sw-5 plus Sw-7 genes for tospovirus resistance in the development of improved breeding lines. The two-gene combination may ultimately be helpful for FL growers should other tospoviruses emerge in the state which are not controlled by either gene alone.Insects and nematodes. Nematode resistance is advanced through the selection of the Mi gene by MAS. Breeding for insect resistance seeks to utilize a single QTL from S. galapagense. A linked molecular marker has been developed, and preliminary seedling screening has demonstrated effectiveness for this QTL to significantly reduce silverleaf whitefly numbers and TYLCV infection. Future efforts will focus on advancing this QTL into elite backgrounds via backcrossing. Insect bioassays will be used throughout the process to verify that resistance is being maintained.2. To develop tomato cultivars and germplasm with improved quality and shelf life. Selection of large, firm, smooth, defect free tomatoes with good flavor and color will continue to be emphasized in all breeding efforts. Top quality inbreds will be extensively used as recurrent parents in all breeding projects. Emphasis will be placed on crimson (ogc) lines to provide Florida growers with high lycopene varieties for improved color and possible anti-cancer advertising. Cooperative work with Dr. Paul Sarnoski at UF Gainesville will seek to determine the importance of specific volatiles in perception of the fruity-floral tomato flavor note within UF/IFAS germplasm. Environmental influences on fruity/floral expression are profound, and knowledge of genetic control will be essential to improve selection efficiency and effectively breed for this characteristic.3. To develop cultivars and germplasm with improved fruit set. Emphasis will be placed on developing heat-tolerant inbreds with increased fruit size, smooth blossom scars, and strong vines. This will require field planting at the beginning of August in order to subject the plants to enough heat stress to make progress. As possible, tolerance to bacterial spot will be incorporated into heat-tolerant inbreds because this disease is problematic in early fall when it is hot and rainy. It will also be important to add TYLCV resistance in this material, and the addition of bacterial wilt resistance will potentially expand utilization of parent lines beyond Florida. The breeding cycle will go from early fall to early fall to establish heat-tolerance. Lines inbred to F4 or more will be assayed in the spring to judge overall potential. The best inbreds will be test crossed and released as breeding lines or in hybrids if merited.4. To develop cultivars and germplasm with compact growth habit. ?Ongoing selection efforts aim to develop improved breeding lines and hybrids with compact growth habit (CGH) and jointless pedicels with the primary goal of achieving plant types that are amenable to mechanical harvest. Selection for the br and j-2 genes will continue. Selection efforts will emphasize higher yield and larger fruit size, which are physiological challenges in CGH tomatoes carrying the br gene. Attention will be paid to minimizing fruit defects that result in losses to marketability; such defects are common in jointless pedicel materials, and selection efforts will therefore prioritize smooth blossom scars, reduced fruit cracking, etc. Selection efforts will also continue to incorporate major resistance genes for several diseases that are economically important in Florida.