The biology of Solanum lycopersicum L. (tomato)

Biology document BIO2025-01: A companion document to Directive 94-08 (Dir94-08), Assessment Criteria for Determining Environmental Safety of Plant with Novel Traits

On this page

1. General administrative information

1.1 Background

The Canadian Food Inspection Agency's Plant Biotechnology Risk Assessment (PBRA) unit is responsible for assessing the potential risk to the environment from the release of plants with novel traits (PNTs) into the Canadian environment.

Risk assessments conducted by the PBRA unit require biological information about the plant species being assessed. Therefore, these assessments are done in conjunction with species-specific biology documents that provide the necessary biological information. When a PNT is assessed, the biology document serves as companion document to Dir 94-08: Assessment Criteria for Determining Environmental Safety of Plants with Novel Traits.

1.2 Scope

This document is intended to provide background information on the biology of Solanum lycopersicum, including:

  • its identity
  • geographical distribution
  • reproductive biology
  • related species
  • the potential for gene introgression from S. lycopersicum into relatives
  • details of the life forms with which it has the potential to interact

Such information will be used during risk assessments conducted by the PBRA unit. Specifically, it may be used to characterize the potential risk from the release of the plant into the Canadian environment with regard to:

  • weediness/invasiveness
  • gene flow
  • plant pest properties
  • impacts on other organisms
  • impact on biodiversity

2. Identity

2.1 Name

Solanum lycopersicum L. Footnote 1

2.2 Family

The cultivated tomato is a member of the genus Solanum, commonly known as nightshades within the Solanaceae family (United States Department of Agriculture (USDA) National Resources Conservation Service). Members of the Solanaceae family include some of the most important food plants, such as the potato, peppers, eggplant, tomatillo, as well as ornamental (petunia, tobacco) and medicinal plants (belladona, datura, henbane) Footnote 2.

2.3 Synonyms

Synonyms for S. lycopersicum include Footnote 3:

  • Lycopersicon esculentum
  • Lycopersicon lycopersicum (L.) Karst.
  • Lycopersicon cerasiforme Dunal
  • Lycopersicon pyriforme Dunal
  • Lycopersicon esculentum ssp. galenii (Mill.) Luckwill
  • Lycopersicon esculentum var. cerasiforme (Dunal) Alef.
  • Lycopersicon esculentum var. esculentum Mill.
  • Lycopersicon esculentum var. cerasiforme (Dunal) A. Gray
  • Lycopersicon esculentum var. leptophyllum (Dunal) D'Arcy
  • Lycopersicon esculentum var. pyriforme (Dunal) L.H. Bailey
  • Lycopersicon lycopersicum var. cerasiforme (Dunal) Alef.
  • Solanum lycopersicum var. cerasiforme (Dunal) Spooner, G.J. Anderson & R.K. Jansen
  • Solanum lycopersicum var. lycopersicum L.
  • Lycopersicon esculentum var. pyriforme (Dunal) Alef.

2.4 Common names

S. lycopersicum is commonly referred as:

  • Tomato
  • Cultivated tomato
  • Garden tomato

2.5 Taxonomy and genetics

S. lycopersicum is a diploid plant with 2n = 24 chromosomes Footnote 4.

Taxonomic position Footnote 3

Taxon: Scientific name (common name)

  • Kingdom: Plantae (plants)
  • Subkingdom: Viridiplantae (green plants)
  • Superdivision : Embryophyta
  • Division: Tracheophyta (vascular plants)
  • Subdivision: Spermatophytina (seed plants)
  • Class: Magnoliopsida
  • Superorder: Asteranae
  • Order: Solanales
  • Family: Solanaceae (nightshades, potatoes)
  • Genus: Solanum (nightshade)
  • Species: Solanum lycopersicum (cultivated tomato, garden tomato)

The classification of tomatoes has undergone significant debate and revision over time. Initially named Solanum lycopersicum by Linnaeus in 1753, various other names such as Lycopersicon lycopersicum and Lycopersicon esculentum have also been used. Today, tomatoes are widely accepted as a member of the genus Solanum, based in the results of both morphological and molecular analyses Footnote 5 Footnote 6.

2.6 General description

The tomato is a herbaceous perennial in frost-free climates, but is cultivated as an annual crop Footnote 7 Footnote 5 Footnote 8. The tomato plant varies in size and can grow from 0.3 up to 3 meters in height and 0.3 to 1.2 meters in width Footnote 8.

The morphological traits most relevant to the reproduction, hardiness, and interactions of tomato with organisms are reported in this paragraph. For additional description, the reader may look on the Solanum lycopersicum website Footnote 8.

The tomato plant exhibits a determinate or indeterminate growth habit, depending on the cultivar Footnote 9 Footnote 10. Determinate varieties stop growing after flowering, set fruit early, and their fruit reach maturity over a short period of time. Indeterminate varieties continue to grow and produce fruit throughout the growing season.

The surface of stem and leaves is covered with non-glandular and glandular trichomes Footnote 11 that give to the tomato plant its distinctive aroma Footnote 5, provide protection against pests, and reduce water loss Footnote 9.

The flowers are borne in clusters, include 5 partially-fused petals, reach a maximal size of 2.5 cm in diameter and are in general yellow Footnote 5, although some varieties have white, gold, or pink petals Footnote 9 Footnote 12. Each flower has 5 stamens and a pistil and is typically self-fertilizing Footnote 9.

From a botanical perspective, the tomato fruit is a berry Footnote 5. The appearance of the fruit varies depending on the variety Footnote 9 Footnote 13. The fruit diameter varies from less than 3 cm to more than 10 cm. The ripe fruit can be green, red, yellow, orange, pink, brown, or purple; even striped or bi-coloured Footnote 9 Footnote 14. Eight fruit shape categories (flattened, slightly flattened, rounded, high rounded, heart-shaped, cylindrical [long oblong], pyriform, and ellipsoid [plum-shaped]) are recognized internationally Footnote 13.

Commonly, the tomato fruit includes multiple compartments (or locules) that house 50-200 seeds, arranged in a radial pattern around the central core. The seeds are small, flattened and exhibit a lentil or kidney-like shape Footnote 9 Footnote 5.

3. Geographical distribution

3.1 Origin and history of introduction

Based on the natural geographic distribution of wild Solanum species, the Solanum genus is presumed to have originated within an area ranging from Columbia to Northern Chile, between the Pacific coast and the Andes, and including the Galapagos Islands Footnote 15 Footnote 16. Peru is believed to be the centre of diversity for wild relatives Footnote 16 Footnote 17. Mexico is the most probable center of diversification and domestication of S. lycopersicum Footnote 16.

It was thought that S. pimpinellifolium underwent selection by humans in Peru and Ecuador to give rise to the semi-domesticated S. lycopersicum var. cerasiforme and that S. lycopersicum cerasiforme (SLC) spread as a weed from the Andean region to Mexico and is the direct ancestor of the modern cultivated tomato Footnote 16. This theory has been challenged by recent genomic evidence suggesting that SLC arose in Ecuador before human presence in the Americas Footnote 18 and that the domestication of tomato involves complex intermediate stages that remain poorly understood. However, results obtained in Razifard et al. (2020) Footnote 18 are consistent with the original theory that SLC spread as a weed from South America to Mexico, where further domestication occurred and led to the cultivated tomato S. lycopersicum. Subsequent genomic studies provided further insights into the complex domestication history of tomato Footnote 19 Footnote 20.

The tomato was introduced to Europe early in the 16th century Footnote 16. In many countries, the acceptance of tomato as food was slow because of the fear of poisoning and it remained an ornamental plant for a long while. In contrast, tomato was successfully adopted as food in Spain and Italy, where S. lycopersicum found a secondary centre for diversification Footnote 21.

Tomatoes were introduced to the United States in 1710 as an ornamental plant but only achieved popularity as food in the 18th century Footnote 22.

Today, the tomato is one of the most widely cultivated and consumed vegetable crops worldwide, with thousands of varieties grown for fresh consumption or processed for various culinary purposes such as canned tomatoes, sauces, ketchup, and juice. The top 3 producing countries in 2022 were China, accounting for nearly 37% of the worldwide production, followed by India and Turkey. The USA, Mexico, and Canada ranked 4th, 7th, and 41st, respectively Footnote 23.

3.2 Native range

S. lycopersicum arose as a crop in Mexico, before being introduced to Europe.

3.3 Introduced range

S. lycopersicum is widely naturalized and is now grown commercially throughout the world Footnote 1. The adaptability of tomato to various climates and growing conditions has contributed to its widespread cultivation Footnote 5.

3.4 Potential range in North America

Tomatoes can be grown across Canada, but with Canada's diverse climate, tomato growers need to adapt their practices to local conditions Footnote 24 Footnote 25 Footnote 26 Footnote 27 Footnote 28. Most large-scale field tomato production occurs in southern Canada, particularly in Ontario, Quebec, and British Columbia, where the growing season is long enough to support outdoor cultivation Footnote 29. Field-grown tomatoes are possible in more northern latitudes in Canada, but it would require careful planning due to the shorter growing seasons, cooler temperatures, and the risk of frost. Strategies would include selecting cold-tolerant and early-maturing varieties, transplanting the plants only after the risk of frost has passed, using mulch, and more Footnote 30. Regions farther north will typically require protective methods like high tunnels or greenhouses to ensure a successful crop.

3.5 Habitat

In Canada, tomato is cultivated as an annual plant due to its very low tolerance to frost Footnote 31 Footnote 32 Footnote 33 Footnote 26. Tomato is grown by home gardeners in all provinces. However, most of the commercial field production takes place in Southern Ontario, where determinate tomatoes are grown from transplants and are set out in the field after the danger of frost has passed Footnote 26 Footnote 33.

Temperature plays a critical role in tomato seed germination and early seedling growth. Although some cultivars germinate well at temperatures as low as 10°C Footnote 34 Footnote 35, seed germination is delayed or inhibited when temperature decreases to 9°C Footnote 36. Seed germination is also delayed under high soil salinity or drought stress Footnote 6. When the temperatures are consistently lower than 20°C, seedling growth is often reduced Footnote 36.

Tomato plants grow best in direct sunlight for 6-8 hours per day with average daytime temperatures between 14°C and 30°C Footnote 26. Tomato is sensitive to temperatures above 30°C or below 14°C. Excessive heat impairs flower development Footnote 37 and reduces pollen viability Footnote 38. The sensitivity of flower fertilization to above-optimal air temperature can translate into yield loss; for example, in protected cultivation, Harel et al. (2014) Footnote 39 found that greater than 90% of fruit set at 25°C but only 50% of fruit set at 27.5°C. Fruit setting and root growth are inhibited at prolonged temperatures below 14°C and chilling injury can occur at temperatures below 10°C Footnote 26 Footnote 28.

Tomatoes need consistent and even moisture, especially during flowering and fruit development Footnote 28. Tomatoes thrive in well-drained soils with pH levels of 5.5 – 7.5, rich in organic matter. Sandy soils, which warm quickly and drain well, are ideal for early season tomato production, while loam soils, with better moisture and nutrient retention, are better suited for mid- to late- season growth Footnote 26. Protection from wind is crucial, particularly during early growth stages, to limit physical damage to the transplant.

4 Biology

4.1 Reproductive biology

The cultivated tomato flowers contain both male and female reproductive organs, which allow for self-pollination to occur within the same flower. According to Kaul (1991) Footnote 7 the stigma can remain receptive from 1 day before anthesis to 6 days after anthesis.

Tomato plants can set fruits without insect pollinators, primarily through natural pollen release when anthers dehisce (open) or the flower is shaken by wind Footnote 40. While pollination efficiency improves with insect visits (increasing fruit set by 7-70%, depending on the environmental conditions), wind remains the dominant factor in field production Footnote 40. Effective pollination requires flower shaking, which can occur naturally through wind movement or be facilitated by certain insect pollinators that vibrate their flight muscles to release pollen Footnote 40. According to Toni et al. (2021) Footnote 40, 77 insect species worldwide can pollinate tomatoes, all belonging to the order Hymenoptera, including 16 well-identified bumblebee species.

Environmental conditions such as high temperature, sunlight, and humidity can affect tomato flower production, pollen viability, and fruit development Footnote 9. At temperatures ranging from 18 to 25°C, pollen retains its viability for 2 to 5 days Footnote 7; however, above optimal temperatures can decrease both the quantity of pollen grains released and pollen germination Footnote 41 Footnote 38, resulting in flower abortion and parthenocarpic fruits Footnote 37.

4.2 Breeding and seed production

As a major crop grown worldwide, the tomato has been subject to intensive breeding efforts since the early 20th century Footnote 22 Footnote 42.

As tomato is subject to many diseases, resistance to pathogens is a major breeding objective. Many disease resistance genes from wild tomatoes have been introgressed into the genome of cultivated tomato Footnote 43 Footnote 44.

Fruit quality has been another major focus of breeding programs (reviewed in Foolad, 2007) Footnote 6. Traits of interest include fruit size, colour, shape, firmness, uniform ripening, nutritional quality (for example, high lycopene content), flavour, and increased total solids (in particular for the processing industry). Cultivars with extended shelf-life that can be harvested at a later maturity stage have been developed by conventional breeding Footnote 6 Footnote 42 and genetic engineering Footnote 45.

Several traits have been selected to develop cultivars suitable for machine harvesting, including determinate growth habit, concentrated fruit set, small vine size, and uniform fruit maturation.

Since the 1970s, fresh market and greenhouse tomato production has been mainly based on F1 hybrids Footnote 42, and in 1990 F1 hybrids became widely used for processing tomatoes (Steven A Loewen, personal communication). The development of male-sterile lines has facilitated hybrid seed production Footnote 46 Footnote 47; however, generation of F1 hybrids still rely largely on manual emasculation, which involves removing the anthers from the flowers of the female parent to prevent self-pollination.

Developing commercial cultivars resistant to abiotic stressors such as drought, salinity, mineral deficiency, or extreme temperature has proven difficult and remains challenging using conventional breeding Footnote 6 Footnote 48.

The tomato genome was entirely sequenced in 2012 (The Tomato Genome Consortium) Footnote 49, and several pangenomes that encompass multiple individual genomes that are representative of the genetic variation within a species have been published (for example, Gao et al, 2019; Zhou et al, 2022) Footnote 50 Footnote 51. Reference genomes of 11 wild species have also been generated (reported in Wang et al., 2024) Footnote 47. These advancements have increased the efficiency of breeding programs through both marker-assisted selection and genomic selection, and pave the way to breeding based on targeted gene-editing Footnote 52 Footnote 47 and de novo domestication Footnote 53 Footnote 54.

Tomato is amenable to transformation by Agrobacterium tumefaciens Footnote 55 and many studies have reported the development of genetically modified tomato lines for a range of traits (reviewed in Gerszberg et al., 2015)Footnote 56. Some tomato lines developed using recombinant DNA technology have been authorized for food use in a few countries, including Canada; however, their commercial release has been very limited. Most of these lines exhibit delayed ripening and one line exhibits insect resistance Footnote 57 Footnote 58. After a period of over 20 years without commercial applications for genetically modified tomatoes, a purple tomato with increased levels of anthocyanins in the fruit was authorized by the USDA in 2022 Footnote 59 and the FDA in 2023 Footnote 60.

4.3 Cultivation and use as a crop

Use

Tomato ranked as the second most grown vegetable or fruit in Canada in 2022 with 528,777 tons in marketed production of fresh tomatoes Footnote 29. Of this amount, nearly 294,000 tons (56%) were produced in greenhouses Footnote 61. Canada's greenhouse tomato production increased to 315,000 tons in 2023, surpassing the production of cucumbers (289.5 million kilograms) and peppers (169.9 million kilograms) Footnote 62. The majority of Canada's field tomatoes (92%) are destined for the processing market (juice, paste, ketchup, etc.) Footnote 61, whereas tomatoes for fresh markets are primarily grown in greenhouses. In 2022, nearly all tomatoes (97.6%) were grown in Ontario, with the remainder grown in Quebec and British Columbia Footnote 29.

Greenhouse production

Greenhouse tomatoes account for 35% of Canada's greenhouse vegetable sales, with Ontario, British Columbia, and Quebec leading production Footnote 61. Tomatoes are typically grown in hydroponic systems, reaching heights of up to 12 meters through vertical trellising. Common varieties grown include cherry, grape, and beefsteak Footnote 63. The production cycle typically lasts 6 to 8 months, with the use of climate control and integrated pest management systems for year-round production and high-quality output Footnote 63 Footnote 61. For more detailed information on greenhouse tomato production, refer to resources from:

Field production

This document focuses on field production. Outdoor cultivation practices for tomatoes, including transplanting, fertilization, irrigation, harvesting and pest management, are discussed in detail in provincial crop production guides and extension material. For example:

In Ontario, tomatoes are typically transplanted to the field early to late May and harvested when they reach maturity within 60-90 days after transplant Footnote 27. Fresh market typically starts in late July, and goes through to late September or the first frost, depending on the planting dates, year, and cultivars Footnote 32.

Additionally, using plastics such as ground mulches, row covers, and tunnel houses can be advantageous for tomato cultivation Footnote 28 Footnote 26.

Crop rotation

Recommended crop rotations include beans, Brassica crops, cereals, corn, peas, and soybean Footnote 27. Rotating with crops of the same family such as eggplants or peppers should be avoided due to their susceptibility to the same or similar diseases Footnote 27 Footnote 26 Footnote 25.

Weeds

Many dicots and monocots may be problematic weeds in tomato fields in Ontario Footnote 64.

Weed control is achieved through an integrated approach using mechanical, manual, and chemical methods Footnote 26. Plastic soil mulches are also used to weeds in fresh market production.

Health Canada's Pest Management Regulatory Authority maintains a database of approved herbicides Footnote 65. Please refer to this database for current information on registered herbicides for weed control in tomato plants. Some herbicides may only be registered for use and sale in certain provinces.

Herbicides may be applied to the soil before planting, immediately after planting tomato plants (pre-emergence), or after tomato plants and weed emergence (post-emergence) to control weeds. Active ingredients include those listed in Table 1.

Table 1: Herbicide active ingredients registered for use on tomato plants. This table is based on products registered as of January 2024 Footnote 65.

Active ingredient Herbicide group/description Weeds controlled
Metribuzin Group 5 (photosynthetic inhibitors at photosystem II)
  • Annual grasses
  • Broadleaf weeds
Trifluralin Group 3 (inhibition of microtubule assembly)
  • Annual grasses
  • Broadleaf weeds
Napropamide Group 15 (inhibitors of cell growth and division)
  • Annual grasses
  • Broadleaf weeds
S-Metolachlor and R-enantiomer Group 15 (inhibitors of cell growth and division)
  • Annual nightshades
  • Nutsedge
  • Annual grasses
  • Broadleaf weeds
Isoxaflutole Group 27 (inhibition of hydroxyphenyl pyruvate diozygenase)
  • Lamb's quarters
  • Redroot pigweed
  • Common ragweed
  • Eastern black nightshade
  • Velvetleaf
  • Barnyard grass
  • Green foxtail
  • Wild buckwheat
  • Yellow foxtail
  • Lady's thumb
Carfentrazone-ethyl Group 14 (inhibition of protoporphyrinogen oxidase)
  • Lamb's quarters
  • Nightshades
  • Pigweeds
  • Purslane
  • Cocklebur
Sulfentrazone Group 14 (inhibition of protoporphyrinogen oxidase)
  • Redroot pigweed
  • Lamb's quarters
  • Wild buckwheat
  • Eastern black nightshade
  • Smooth crabgrass
  • Large crabgrass
  • Green pigweed
  • Purslane
Halosulfuron (canyon) Group 2 (inhibition of acetolactate synthase)
  • Nutsedge
Pelargonic acid Group 26
  • Eastern black nightshade
  • Purslane
  • Smooth crabgrass

4.4 Gene flow during commercial seed and fruit production

Although tomato is predominantly self-pollinated, natural cross-pollination among commercial varieties may occur in the field. Various natural outcrossing rates have been reported in the scientific literature, ranging from 0 to 15%. For example, Horneburg and Becker (2018) Footnote 66 observed outcrossing rates between 0.0% and 5.2% with plants seeded 1 m apart, with a strong effect of the cultivar and the environment. Distance between plants, variety characteristics such as style length, climatic conditions, presence of pollinators, and wind direction, influence the level of natural cross-pollination Footnote 67 Footnote 68 Footnote 7.

The rate of cross-pollination decreases rapidly with the increased distance from the pollen source Footnote 69 and minimal viable pollen is transferred beyond 30 m from the pollen source Footnote 5. In Canada, tomatoes cultivated for pedigreed seed production must be separated from other tomato plants by an isolation distance of 30.5 m (Canadian Seed Growers' Association, Circular 6, 2017 – PDF) Footnote 70.

S. lycopersicun is not invasive to natural habitats in Canada. Therefore, the potential risk of gene flow from cultivated to wild populations of S. lycopersicum is negligible.

4.5 Cultivated tomato as a weed

Weediness

S. lycopersicumis not listed in the Weed Seeds Order, 2016 Footnote 71. It is not reported as a pest or weed in managed ecosystems in Canada, nor is it recorded as being invasive of natural ecosystems. No reports of significant feral populations in natural environments in Canada were found.

Tomato volunteers

Tomatoes are cold sensitive and will typically be killed by frost. Spring frost often kills tomato volunteers and there is no evidence that volunteer tomatoes establish themselves as persistent weeds in Canada. Additionally, tomatoes are very sensitive to many herbicides Footnote 72 Footnote 73 and chemical weed control applications on the subsequent crop will typically eliminate all volunteer tomatoes if any survive the spring frosts.

Seed dormancy

Tomatoes undergo primary dormancy during seed development Footnote 74. This dormancy may be broken by various seed priming methods that involve controlled hydration and dehydration of seeds, or subjecting seeds to various treatments Footnote 75 Footnote 76. Factors influencing tomato seed viability and germination have been extensively studied Footnote 74 Footnote 44 Footnote 77 Footnote 78, however, there were no studies found that evaluated the length of time tomato seeds could remain in the seedbank, in the Canadian environment, or elsewhere. Due to the low national occurrence and impact of tomato volunteers, research and control practices discussed in the following sections are somewhat limited.

4.5.1 Cultural/mechanical control

Reducing harvest losses will minimize the number of potential tomato volunteers. Surviving tomato volunteers in other crops can be easily controlled using mechanical means or hand weeding.

4.5.2 Chemical control

No herbicides are currently registered for the control of tomato volunteers specifically Footnote 65. As tomatoes are highly sensitive to many herbicides, tomato volunteers are generally eliminated by herbicide applications on the subsequent crop Footnote 72 Footnote 73.

4.5.3 Integrated weed management

Integrated weed management (IWM) uses a combination of biological, mechanical, and chemical weed control tactics to manage weed populations and maximize economic returns. There are no IWM strategies specific to the control of tomato volunteers. Tomato volunteers will likely be controlled by IWM programs used for managing other weed species.

4.6 Means of movement and dispersal

There is little data relating to tomato seed movement and dispersal in the literature. The contribution of various vectors to tomato seed dispersal remains largely undetermined, although S. lycopersicum seeds are likely to be dispersed by animals that consume the seeds.

5. Related species of Solanum lycopersicum

All wild tomato species and close relatives are native to western South America and are found in various ecosystems from sea level to altitudes up to 4,000 meters Footnote 79 Footnote 80. The taxonomic classification of wild tomatoes has varied based on the authors. Peralta et al. (2008) Footnote 81 have proposed the following classification for the cultivated tomato, 12 wild tomato relatives, and 4 closely related species. See also Knapp and Peralta 2016 Footnote 82.

Solanum section Lycopersicon includes:

  • the cultivated tomato, S. lycopersicum, including S. lycopersicum var. cesariforme (cherry tomato)
  • 12 wild tomato species
    • S. arcanum
    • S. cheesmaniae
    • S. chilense
    • S. chmielewskii
    • S. corneliomulleri
    • S. galapagense
    • S. habrochaites
    • S. huaylasense
    • S. neorickii
    • S. pennellii
    • S. peruvianum
    • S. pimpinellifolium

All are endemic to western South America from Ecuador to northern Bolivia and Chile, with 2 that are endemic in the Galapagos Islands. S. arcanum, S. corneliomulleri, S. huaylasense, and S. peruvianum were previously grouped within a single species (S. peruvianum) Footnote 81.

The nearest relatives of wild tomatoes are:

  • 2 species of Solanum section Juglandifolia, distributed in Colombia, Ecuador, and Peru:
    • S. juglandifolium
    • S. ochranthum
  • 2 species of Solanum section Lycopersicoides, distributed in southern Peru and northern Chile:
    • S. lycopersicoides
    • S. sitiens

5.1 Inter-species/genus hybridization

Reciprocal crosses are possible between the cultivated tomato and wild relatives of the Lycopersicon section including:

Crosses with S. arcanum Footnote 86, S. neorickii Footnote 84, or S. chmielewskii Footnote 83 Footnote 84 may only be successful when S. lycopersicum is the female parent.

Crosses with S. chilense, S. corneliomulleri, or S. huaylasense as male parent are unsuccessful or necessitate embryo rescue Footnote 83 Footnote 84 Footnote 85. Crosses with S. lycopersicoides as the male parent are possible, but S. sitiens is not directly crossable with cultivated tomato Footnote 87.

5.2 Potential for introgression of genetic information from Solanum lycopersicum into relatives

Tomato wild relatives are native to South America and are not naturally present in Canada. Therefore, introgression of genetic information from S. lycopersicum into wild tomatoes is not anticipated in Canada.

As indicated in Section 2.2, S. lycopersicum is a member of the Solanaceae family. Weed species in the Solanaceae family include Footnote 88:

  • S. americanum (America black nightshade)
  • S. carolinense (Carolina nightshade, horse nettle or ball nettle)
  • S. dulcamara (bittersweet nightshade)
  • S. emulans (eastern black nightshade) (syn: S. ptychanthum)
  • S. elaeagnifolium (Silverleaf nightshade)
  • S. interius (plains black nightshade)
  • S. nigrum (black nightshade)
  • S. nitidibaccatum (hairy nightshade)
  • S. physalifolium (ground-cherry nightshade)
  • S. rostratum (horned nightshade)
  • S. sisymbriifolium (sticky nightshade)
  • S. sarrachoides (hairy nightshade)
  • S. triflorum (cut-leave nightshade or wild tomato)

The following details the distribution and habitat for each of these species in Canada.

S. americanum is an introduced species in British Columbia and Manitoba Footnote 88. It is an annual species and is considered rare in Canada Footnote 89. It is a Tier 3 designated noxious weed in Manitoba Footnote 90.

S. carolinense is an introduced species in Ontario, Quebec, and Nova Scotia. It is a perennial species found in cultivated fields, pastures, gardens, nurseries, riverbanks, roadsides, and disturbed areas Footnote 91 Footnote 92. It is a prohibited noxious weed, Class 2 in the Canadian Weed Seeds Order, 2016 under the Seeds Act Footnote 91.

S. dulcamara is an introduced species in British Columbia, Saskatchewan, Ontario, Quebec, New Brunswick, Nova Scotia, Prince Edward Island, and Newfoundland Footnote 88. It is also present as an ephemeral species in Manitoba Footnote 88. It is a perennial species found in wet soils, cultivated fields, pastures, gardens, hedgerows, fencerows, shores, forests, ditches, roadsides, and disturbed areas Footnote 89. This species is considered an invasive plant of concern in British Columbia Footnote 93.

S. emulans is native to Saskatchewan, Manitoba, Ontario, and New Brunswick and an introduced species in British Columbia, Quebec, and Nova Scotia Footnote 88. It is an annual species found in cultivated fields, gardens, shores, open forests, roadsides, and disturbed areas Footnote 89. Some populations of this weed are resistant to Group 2 and Group 22 herbicides Footnote 94.

S. elaeagnifolium is not currently present in Canada Footnote 95. It is a prohibited noxious weed, Class 1 in the Canadian Weed seeds order, 2016 under the Seeds Act Footnote 95. It is also listed on the List of pests regulated by Canada established under the Plant Protection Act Footnote 95.

S. interius is an introduced species in Saskatchewan Footnote 88.

S. nigrum is an introduced species in British Columbia, Ontario, and Nova Scotia Footnote 88. It is an annual species found mostly in cultivated fields, old fields, roadsides, and disturbed areas Footnote 89. This is an invasive plant of concern in British Columbia Footnote 93.

S. nitidibaccatum is an introduced species in all provinces except Prince Edward Island and Labrador. It is also present as an ephemeral species in Newfoundland Footnote 88.

S. physalifolium has been reported in Canada, but its presence has not been confirmed or may have been incorrectly identified Footnote 88.

S. rostratum is an introduced species in British Columbia, Manitoba, Ontario, Quebec, New Brunswick, and Nova Scotia Footnote 88. It is an annual species occasionally found in pastures, gardens, roadsides, and disturbed areas Footnote 89.

S. sarrachoides is common to the Prairie provinces and southern British Columbia, but rare elsewhere Footnote 89. It is a Tier 3 designated noxious weed in Manitoba Footnote 90 and is considered an invasive plant of concern in British Columbia Footnote 93.

S. sisymbriifolium has been reported in Ontario, but its presence has not been confirmed or may have been incorrectly identified Footnote 88.

S. triflorum is native to Alberta and Saskatchewan and an introduced species in British Columbia, Manitoba, Ontario, and Quebec Footnote 88. It is an annual species commonly found in cultivated fields, dry plains, open forests, roadsides, and disturbed areas Footnote 89. It is a Tier 3 designated noxious weed in Manitoba Footnote 90.

No report or scientific publications were found regarding the ability of S. lycopersicum to hybridize with any of the above-mentioned species. While there is sexual compatibility between S. lycopersicum and wild tomatoes (section 5.1), even artificial crosses are challenging to make. Therefore, the potential for the unintended introgression of genetic information from S. lycopersicum to its more distant relatives in Canada is unlikely.

6. Potential interaction of S. lycopersicum with other life forms

Information on the management of many diseases and pests of tomato can be found in provincial publications (Government of British Columbia, 2024 Footnote 24; Government of Alberta, 2014 Footnote 25; Perennia, 2023 Footnote 96; Government of Manitoba, undated Footnote 26; Government of Ontario, 2024 Footnote 27). Diseases in tomato due to various virulent fungi and oomycetes (see Table 2), bacteria (see Table 3), and viruses (see Table 4) can cause significant yield losses and require careful management. Many tomato varieties have been bred to tolerate certain tomato diseases.

Nematodes including root-knot and root-lesion nematodes (see Table 5) may feed on tomato roots, interfering with the tomatoes nutrient uptake and allowing the establishment of other diseases. Nematodes also can impact the water and nutrient uptake of tomato from the soil, which taken together with root damage may be major contributing factors for declining productivity and tomato production in Ontario Footnote 97.

Insect feeding on tomatoes depends heavily on environmental conditions. Frequent scouting and control during the growing season is needed to protect yield and quality. Insect pests (see Table 6) may kill tomato plants or could increase the plants' susceptibility to disease. Natural enemies present in tomato fields can help to control a number of pests including leaf miners and aphids.

Refer to the tables below for examples of interactions of tomato with other life forms:

Abbreviation list for tables

  • BC – British Columbia
  • AB – Alberta
  • SK – Saskatchewan
  • MB – Manitoba
  • ON – Ontario
  • QC – Quebec
  • NB – New Brunswick
  • NS – Nova Scotia
  • PE – Prince Edward Island
  • NL – Newfoundland & Labrador

Table 2: Fungi and oomycetes

Fungi and Oomycetes Interaction with tomato (pathogen; symbiont or beneficial organism; consumer; gene transfer) Presence in Canada Reference(s)

Anthracnose

  • Colletotrichum spp.
 pathogen widespread Government of Ontario (2024) Footnote 64; Government of Manitoba (undated) Footnote 26; Government of British Columbia (2024) Footnote 24; Perennia (2023) Footnote 96

Black mold (Altenaria fruit rot)

  • Alternaria solani
  • Alternaria alternata
 pathogen ON, AB Government of Ontario (2024) Footnote 64; Government of Alberta (2014) Footnote 25

Botrytis gray mold

  • Botrytis cinerea
 pathogen widespread Government of Ontario (2024) Footnote 64; Government of British Columbia (2024) Footnote 24; Government of Alberta (2014) Footnote 25; Perennia (2023) Footnote 96

Early blight

  • Alternaria tomatophila
  • Alternaria solani
 pathogen widespread Government of Ontario (2024) Footnote 64; Government of Manitoba (undated) Footnote 26; Abbasi and Weselowski (2014) Footnote 98; Government of British Columbia (2024) Footnote 24; Government of Alberta (2014) Footnote 25; Perennia (2023) Footnote 96

Fusarium wilt

  • Fusarium oxysporum
 pathogen MB, ON Government of Manitoba (undated) Footnote 26

Late blight

  • Phytophthora infestans
 pathogen widespread Government of Ontario (2024) Footnote 64; Government of Manitoba (undated) Footnote 26; Government of British Columbia (2024) Footnote 24; Government of Alberta (2014) Footnote 25; Perennia (2023) Footnote 96

Leaf mold

  • Passalora fulva
 pathogen ON Government of Ontario (2024) Footnote 64

Phytophthora Blight

  • Phytophthora capsici
 pathogen NS, ON Perennia (2023) Footnote 96

Powdery mildew

  • Pseudoidium neolycopersici
  • Leveillula taurica
 pathogen ON, NS Government of Ontario (2024) Footnote 64; Perennia (2023) Footnote 96

Septoria leaf spot

  • Septoria lycopersici
 pathogen MB, NS, ON Government of Ontario (2024) Footnote 64; Government of Manitoba (undated) Footnote 26; Perennia (2023) Footnote 96

Verticillim wilt

  • Verticillium dahliae
  • Verticillium albo-atrum
 pathogen widespread Government of Ontario (2024) Footnote 64; Government of Manitoba (undated) Footnote 26; Government of British Columbia (2024) Footnote 24; Government of Alberta (2014) Footnote 25; Perennia (2023) Footnote 96

Sclerotinia white mold

  • Sclerotinia sclerotiorum
  • Sclerotinia minor
 pathogen ON Government of Ontario (2024) Footnote 64

Table 3: Bacteria

Bacteria Interaction with tomato (pathogen; symbiont or beneficial organism; consumer; gene transfer) Presence in Canada Reference(s)

Bacterial soft rot

  • Pectobacterium carotovorum
  • Dickeya chrysanthemi
 pathogen ON Government of Ontario (2024) Footnote 64

Bacterial canker

  • Clavibacter michiganensis subsp. michiganensis
 pathogen MB, ON, BC Government of Ontario (2024) Footnote 64; Government of Manitoba (undated) Footnote 26; Government of British Columbia (2024) Footnote 24; Government of Alberta (2014) Footnote 25; Perennia (2023) Footnote 96

Bacterial speck

  • Pseudomonas syringae pv. tomato
 pathogen MB, ON, BC Government of Ontario (2024) Footnote 64; Government of Manitoba (undated) Footnote 26; Government of British Columbia (2024) Footnote 24

Bacterial spot

  • Xanthomonas campestris pv. Vesicatoria
  • Xanthomonas euvesicatoria
  • Xanthomonas perforans
  • Xanthomonas gardneri
 pathogen MB, ON, BC Government of Ontario (2024) Footnote 64; Government of Manitoba (undated) Footnote 26; Government of British Columbia (2024) Footnote 24; Perennia (2023) Footnote 96 Abbasi, et al., (2015) Footnote 99

Table 4: Viruses

Virus Interaction with tomato (pathogen; symbiont or beneficial organism; consumer; gene transfer) Presence in Canada Reference(s)
Cucumber mosaic virus (CMV) pathogen ON Government of Ontario (2024) Footnote 64
Tomato mosaic virus (ToMV) pathogen MB, ON Government of Ontario (2024) Footnote 64; Government of Manitoba (undated) Footnote 26
Tobacco mosaic virus (TMV) pathogen ON, BC Government of Ontario (2024) Footnote 64; Government of British Columbia (2024) Footnote 24
Tomato spotted wilt virus (TSWV) Vector: western flower thrips, Frankliniella occidentalis pathogen MB, ON, BC Government of Ontario (2024) Footnote 64; Government of Manitoba (undated) Footnote 26; Pitblado et al. (1990) Footnote 100; Government of British Columbia (2024) Footnote 24
Tobacco ringspot virus (TRSV) pathogen ON Government of Ontario (2024) Footnote 64
Tomato brown rugose fruit virus (ToBRFV) pathogen ON Zhang, et al., (2022) Footnote 101

Table 5: Nematodes

Nematodes Interaction with tomato (pathogen; symbiont or beneficial organism; consumer; gene transfer) Presence in Canada Reference(s)

Root-knot nematodes

  • Southern root-knot nematode, Meloidogyne incognita
  • Northern root-knot nematode, Meloidogyne hapla
 consumer ON Johnson and Potter (1980) Footnote 102; Perennia (2023) Footnote 96

Root-lesion nematodes

  • Pratylenchus spp.
 consumer widespread Potter and Olthof (1977) Footnote 103

Table 6: Insects

Insects Interaction with tomato (pathogen; symbiont or beneficial organism; consumer; gene transfer) Presence in Canada Reference(s)

Aphids including

  • Green peach aphid, Myzus persicae
  • Potato aphid, Macrosiphum euphorbiae
 consumer widespread Government of Ontario (2024) Footnote 64; Government of Manitoba (undated) Footnote 26; Government of British Columbia (2024) Footnote 24; Government of Alberta (2014) Footnote 25; Perennia (2023) Footnote 96

Cabbage looper

  • Trichoplusia ni
 consumer widespread Government of Ontario (2024) Footnote 64; Perennia (2023) Footnote 96

Colorado potato beetle

  • Leptinotarsa decemlineata
 consumer widespread Government of Ontario (2024) Footnote 64; Government of Manitoba (undated) Footnote 26; Government of British Columbia (2024) Footnote 24; Government of Alberta (2014) Footnote 25; Perennia (2023) Footnote 96

Corn earworm / tomato fruitworm

  • Helicoverpa zea
 consumer widespread Government of Ontario (2024) Footnote 64; Perennia (2023) Footnote 96

Cutworms

  • Black cutworm, Agrotis ipsilon
  • Variegated cutworm, Peridroma saucia
  • Dingy cutworm, Feltia jaculifera
 consumer widespread Government of Ontario (2024) Footnote 64; Government of Manitoba (undated) Footnote 26; Government of British Columbia (2024) Footnote 24; Government of Alberta (2014) Footnote 25; Perennia (2023) Footnote 96

European corn borer

  • Ostrinia nubilalis
 consumer widespread Perennia (2023) Footnote 96

Flea beetles

  • Potato flea beetle, Epitrix cucumeris
  • Palestriped flea beetle, Systena blanda
 consumer MB, OB, QB BC, MB, ON, QB Government of Ontario (2024) Footnote 64; Government of British Columbia (2024) Footnote 24; Perennia (2023) Footnote 96
Grasshoppers and crickets consumer widespread Government of Manitoba (undated) Footnote 26; Government of Alberta (2014) Footnote 25

Spotted wing drosophila

  • Drosophila suzukii
 consumer BC, MB, ON, QB, NS, PEI Perennia (2023) Footnote 96

Stink bugs

  • Brown marmorated stink bug, Halyomorpha halys
  • Brown stink bug, Euschistus servus
  • One-spotted stink bug, Euschistus variolarius
  • Green stink bug, Chinavia hilaris (formerly Acrosternum hilare)
 consumer widespread (Euschistus variolarius only in BC, MB, ON, QB) Government of Ontario (2024) Footnote 64; Perennia (2023) Footnote 96

Tarnished plant bug

  • Lygus lineolaris
 consumer widespread Government of Ontario (2024) Footnote 64; Government of Manitoba (undated) Footnote 26

Tobacco hornworm

  • Manduca sexta
 consumer MB, BC, ON, QB Government of Ontario (2024) Footnote 64; Government of Manitoba (undated) Footnote 26; Government of British Columbia (2024) Footnote 24; Perennia (2023) Footnote 96

5-spotted hawkmoth

  • Manduca quinquemaculata
 consumer BC, ON, QB Government of Ontario (2024) Footnote 64

Western flower thrips

  • Frankliniella occidentalis
 consumer widespread Government of Ontario (2024) Footnote 64; Kirk and Terry (2003) Footnote 104

Wireworms

  • Limonius spp.
  • Ctenicera spp.
  • Agriotes spp.
 consumer widespread Government of Ontario (2024) Footnote 64; Government of Alberta (2014) Footnote 25

Table 7: Animals

Animals Interaction with tomato (pathogen; symbiont or beneficial organism; consumer; gene transfer) Presence in Canada Reference(s)

Animal browsers including

  • deer
  • rabbits
  • raccoons
  • groundhogs
  • rodents
 consumer widespread

Facultative frugivorous birds

  • American crow (Corvus brachyrhynchos)
 consumer widespread Birds Academy (2021) Footnote 105
Insectivorous birds beneficial widespread

Mites including

  • Tomato russet mite, Aculops lycopersici
  • 2-spotted spider mite, Tetranychus urticae
 consumer widespread Government of Ontario (2024) Footnote 64; Government of British Columbia (2024) Footnote 24; Government of Alberta (2014) Footnote 25; Perennia (2023) Footnote 96
Slugs consumer widespread Kazak et al. (2015) Footnote 106
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