Recipient Organization
UNIV OF MINNESOTA
(N/A)
ST PAUL,MN 55108
Performing Department
Horticultural Science
Non Technical Summary
This project is Phase II of the University of Minnesota tomato breeding program to develop elite tomato varieties for growers in short-season locations and urban communities.Tomatoes are a rich source of vitamins and antioxidants valuable to human diets. With 80 pounds of tomatoes consumed yearly on average by each American, tomato is the 2nd most popular home garden plant, and field crop. Among the thousands of tomato varieties, only a few varieties have been introduced to the northern latitudes with short-season growth and low yield. Many heirloom tomatoes face challenge to grow in short-season areas such as northern part of Minnesota, Dakotas, and Wisconsin. The obstacles of environment, available varieties, and maintenance cost have discouraged home gardeners and commercial growers for investing in tomato production. This is extremely true to the residents who live in the urban communities with limited access to spacious garden plots. We commit to fill these gaps by breeding for dwarf, high-yield, cage free, short-growing season tomatoes for potted plants, home gardens, and large scale vegetable farms. These varieties can also be used to improve specific traits such as fruit shape, color, and nutritional compounds with a purpose of being used for food and ornamentals.We apply the classical cross-selection approach, expecting to develop 5-8 new tomato varieties, both determinant and indeterminant growth habit. This will add significantly to the total of ~50 available cultivars for growing in short-season locations or small spaces such as patios. All new cultivars should be evaluated as elite and non-GMO crops, which will be an essential complement for those bred through molecular breeding methods including gene editing. This project will include outreach activities with a wide-range participants including students, growers, educators, and research scientists.
Animal Health Component
60%
Research Effort Categories
Basic
20%
Applied
60%
Developmental
20%
Goals / Objectives
Tomato, Solanum lycopersicum L., is native to South and Central America and is now extensively cultivated throughout the world. Tomatoes are a rich source of vitamins and antioxidants valuable to human diets (Beecher, 1998; George, et al., 2004). On average, Americans consume nearly 80 pounds of tomatoes every year (Jones, JB, 2008), making it the 2nd most eaten vegetable in the United States. There are more than 7,000 tomato varieties available for home and commercial garden use. However, most varieties are adapted to high tropical and subtropical temperatures. Many varieties require 60 to 95 days to mature. Only a few varieties have been introduced for use in northern latitudes. These northern varieties mature in 45 days with low yield. These characteristics limit the choices of economically valuable varieties for growth in short-season farms and home gardens (Jones, JB, 2008). Our long-term goal is to develop dwarf and shrub-like tomato varieties to be grown in Northern latitudes using molecular, cytogenetic and conventional breeding techniques. To realize this goal, in the past 5 years, we have been breeding for dwarf tomato varieties that yield high quality and quantity of fruits under short growing seasons (Phase I). Three dwarf and determinant tomato varieties (Ground JewelTM, Ground DewTM, and MTX851) are being released for growing in the northern farm fields and home gardens. With our state-wide trials, we have found that there is a great need for novel tomato varieties that are not only able to grow in the short-season locations to full maturity, but also for those cultivars that can serve both vegetable and ornamental purposes. This is of particular interest to the urban gardeners (small home gardens, patios, and potted house plants).Our breeding goal for this phase (Phase-II) is to develop economically valuable novel dwarf tomato varieties that can serve both for vegetable production and the ornamental plant market. These varieties can be grown in pots, home gardens, and commercial greenhouses and farms in the cool, and short-season locations such as northern Minnesota and Canada. These varieties will also be the source for future development of new varieties with improved human nutritional components. The specific objectives of the Phase-II research are to: 1) develop 2-3 dwarf tomato varieties with different plant forms; 2) select 3-5 novel dwarf tomato varieties with various novel fruit shapes; 3) create dwarf tomato lines with specific nutrition-enrichment and fruit colors; 4) conduct trials of newly developed tomato varieties to evaluate their performance under different growth conditions.
Project Methods
Since 2007, we have been working on the development of dwarf tomato varieties through genetic crosses and selections (Phase I). In the F2 populations developed from crosses between the indeterminate varieties, Zac-heart, Amana Orange, Aunt Rubys German Green, and Indigo Rose to the miniature determinate cherry tomato variety MicroTom, we observed more than 50 different phenotypes and screened for dwarf and short-season varieties. There are some 20 varieties showing dwarf, short-season, stick/cage free, and high-yield for up to 8 generations. In project phase I (2014-2019), we selected Ground JewelTM and Ground DewTM as elite dwarf varieties for production and gardening in short-season locations. Both Ground JewelTM and Ground DewTM met the growers' needs for short season, high-yield, decent flavor, and good performance in large scale farm fields, as well as small garden plots or potted plants.In Phase II, we plan to screen for more compact varieties with potential for not only being used as vegetables, but also ornamentals, especially for those varieties with different plant form, fruit shape, color, and flavor. Offspring from previous populations have shown unique and exciting features that would be of interest to growers, especially for those living in urban communities. New traits are still segregating and in need for continuous selection in the field for additional generations, until the rate for off-type plants becomes less than 1/1000. Here is a list of detailed activities we plan to perform:Obj. 1. Develop 2-3 dwarf tomato varieties with different plant forms (with R. Murphy).Obj. 1.1 Field screening and trials for compact indeterminate varieties Screen for stable phenotypes of MTX095606 and MTX013702. MTX095606 is a shrub-like indeterminate variety growing tight fruit clusters. MTX013702 is also a shrub-like indeterminate variety with thick and dark green leaves and developing a ring structure in the middle of its fruit.Obj. 1.2. Field screening and trials for dwarf determinate varieties Screen for stable phenotypes of MTX095601 and MTX0851. MTX095601 is a bush-like determinate variety with heavily loaded fruits. MTX0851 is also a bush-like determinate variety with high quality and quantity of fruits and each fruit develops a pointer.Obj. 2. Select 3-5 novel dwarf tomato varieties with various fruit shapes (with R. Murphy).Obj. 2.1. Determine the genetic mechanisms that control the development of a ring structure in the middle of tomato fruits.MTX0137 segregates several lines that develop a ring structure in the middle of each fruit. Fruit develops a ring structure with or without a pointer at the tip (the number "8" shaped fruit). The number "8" is considered lucky in many Asian cultures. Understanding the genetic mechanisms controlling the unique fruit type and consolidating the trait will be of great benefit to gardeners and consumers in Asian countries and local markets due to the potential market demand. For growers in North America, the unique fruit type is also of interest to grow as an edible ornamental plant. In addition, the fruit has a rich flavor with Brix values up to 8, making it a desirable tomato variety for fresh market.A number of factors have been identified to control tomato fruit shape and size, including retrotransposon-mediated gene duplications, and several protein interactions associated with microtubule dynamics. The fruit shape and weight are believed to be regulated mainly before anthesis. Our hypothesis for the ring structure development is associated with pollination and fertilization. We will test our hypothesis by growing MTX013701 under three conditions: greenhouse without shaking plants at flowering time, greenhouse with shaking plants at flowering time, and open field with bees and wind force shaking plants. To measure the factors contributing to the ring structure development, flower samples at 2DBA (day before anthesis), 1DBA, 0DBA (the day of anthesis), 1DAA (day after anthesis), 2DAA will be collected and analyzed. We will select plants with stable "8" shaped fruits for further trials. This process may take more than 3 generations.Obj. 2.2. Select dwarf varieties with novel fruit forms We will screen for dwarf vatieties that produce various types of fruits, especially for the regular round shape fruit, heart shape fruit, olive shape fruit, and fruit with pointers. we will select 2-3 new varieties focusing on the trait of fruit shape.Obj. 3. Create dwarf tomato lines with specific nutrition-enrichment and fruit colors (with R. Murphy)Tomato fruit color is often associated with contents of nutritional compounds such as anthocyanins, lycopene, carotene, which are also connected to fruit flavor. We have observed several dwarf tomato lines developing white, black, purple young fruits and a wide range of mature fruit color including red, pink, yellow and green.Obj. 3.1. Determine the genetic mechanisms of white fruit tomato varieties.MTX0232 is a breeding line producing white fruits while young. One hypothesis is that this is due to photo bleaching. To test this hypothesis, we will grow MTX0232 plants in the controlled growth chamber and reduce the light intensity during the fruit development to see whether the white fruits are developed. Another hypothesis is that there is a defect in plastid (chloroplast) development in fruit. We will measure the pigment metabolome in the fruits using a GC-MS approach.Obj. 3.2. Select dwarf varieties with various fruit color.Selection of stable fruit color traits will be performed together with Obj. 2.2. We will select tomato lines with different fruit color and analyze nutritional compounds, including anthocyanins, lycopene, carotene, carbohydrate, proteins, and vitamins. We aim to select 2-3 elite lines focusing on fruit color with rich lycopene, carotene, and anthocyanin.Obj. 4. Conduct trials for newly bred tomato varieties to evaluate their performance under different growth conditions (With R. Murphy and V. Averello)Newly selected varieties from Obj. 1-3 will be further tested for growing in various conditions.Obj. 4.1. Trials for potted plants.We will grow Ground JewelTM , Ground DewTM, MTX0851, MTX0232, MTX0137 to evaluate their performance as potted plants. For MTX0232 (Fig. 3G), we will also test for hanging basket. Obj. 4.2 Trials for greenhouse and high tunnel plantsAll the new lines selected from Obj. 1-3 will be tested for growing under controlled environment, especially for greenhouse and high tunnels. We will document the fruit quality and quantity, days to the first harvest, etc.Obj. 4.3 Trials for growing in the different climate.At least 5 selected elite lines from Obj. 1-3 will be tested for growing within MN's different climatic zones. We will conduct growing trials on the selected lines from Zone 5 (southern Minnesota) to Zone 3 (north Minnesota) to evaluate their performance and document fruit quality and days to until first harvest.