Making the Modern Tomato

By Annika Peterson

For many Midwesterners, devouring delicious tomatoes that ripen near the end of the summer is a highlight of the year. There are endless ways to enjoy summer’s bounty, from elaborate dishes to just some salt and pepper embellishment. Many varieties of juicy, ripe tomatoes can be found in backyards, farmers markets, and grocery stores. All of the tomatoes we enjoy come from a single species, Solanum lypcopersium. The history of this crop is long, with many changes in shape, color, and geographic location over time. Even now, its identity is still changing!

The tomatoes we enjoy today didn’t exist thousands of years ago. At first, South Americans domesticated the wild ancestors of the modern tomato [1]. Since cultivation proved more efficient than gathering crops, they selected seeds from the plants that best fit their needs. For example, they picked and grew easy-to-cultivate and pleasant tasting tomatoes more often. Nowadays, this selection process continues in modern fields and research labs.

“The process of modern breeding has drastically changed the tomato in the last 100 years [1]. Farmers and plant breeders have selected for larger fruits with a pleasant shape and color, and varieties that are easy to harvest.”

Plant breeders continue to choose traits that improve our crops, but now they use genetic methods to identify genes that cause certain characteristics. They have found the best ways to breed and grow plants to improve qualities like yield, disease resistance, and appearance. Researchers can also identify when and where key changes took place in the evolution of the plant genes [1]. The process of modern breeding has drastically changed the tomato in the last 100 years [1]. Farmers and plant breeders have selected for larger fruits with a pleasant shape and color, and varieties that are easy to harvest.

Because breeding focuses on qualities like yield and size, another key quality–taste–has been lost. Some people may notice that tomatoes bought at a farmers’ market taste better than those purchased at a grocery store. Often, the types of tomatoes sold at farmers’ markets are heirloom varieties, a term that is not well defined, but suggest a tomato variety that has been cultivated and passed down from grower to grower for at least 50 years [2]. On the other hand, tomatoes produced by modern breeding are brightly colored, easy to transport, and are available in supermarkets year-round.

While widely available, they may not be as tasty as those found in the farmers’ market. Though researchers have concluded that the balance of acid to sugar affects the taste of a tomato, smell also plays a significant role. A diverse set of volatile compounds or molecules that we smell when they vaporize, affect the flavor of a tomato [2]. Even though volatile compounds change the way a tomato tastes, plant breeders did not take them into consideration [2]. A recent study explored this through the comparison of heirloom, modern, and the closest wild (not cultivated) relatives to the tomato we know. In modern cultivars, lower levels of flavor volatiles are present, indicating less flavor in these tomatoes. Another difference between older and modern varieties is the genes associated with sugar content. As breeding continued, the average fruit size increased at the expense of decreased sugar content and flavor [2]. Through these changes over time, yield and ease of harvest was increased while flavor decreased. Utilizing modern genetic technologies, researchers can understand how the genetic makeup of a crop causes the qualities we see and taste, and how it changes over time.

“A recent study explored this through the comparison of heirloom, modern, and the closest wild (not cultivated) relatives to the tomato we know. In modern cultivars, lower levels of flavor volatiles are present, indicating less flavor in these tomatoes.”

At the University of Wisconsin-Madison, researchers do consider flavor in deciding what tomatoes to grow and research. An experiment is taking place that includes flavor as one of its main considerations when evaluating tomato varieties. Dr. Julie Dawson in the Horticulture Department here at UW-Madison studies tomatoes under organic or low input conditions. In other words, tomatoes grown with little use of pesticides or fertilizers. At harvest time of the most recent year of the study, Dawson’s team evaluated characteristics of the tomatoes for both yield and disease, but most importantly also taste. In the evaluation, quantitative measurements of sweetness and acidity were matched with qualitative assessments from the public and local chefs [3]. This unique way of measuring the taste of tomatoes gave new and useful information to farmers, plant breeders, and chefs alike. A recent event called Farm to Flavor featured this unique and innovative method of evaluating crops. Chefs prepared unique dishes with local farmers and researchers’ vegetables to celebrate and share this research with the public [4].

This research adds to the story of the modern tomato. The humble tomato has changed over hundreds of years to give us the delicious fruit we enjoy today. From domestication to modern genetic analysis, we have changed this crop to fit our needs. While production and resistance to disease increased, tomato flavor decreased. However, with the exciting recent work to understand the flavor of tomatoes, the future of tomatoes looks delicious.

REFERENCES

1. Blanca J, Montero-Pau, Sauvage C, Bauchet G, Eudald I, José Díez M et al. Genomic
variation in tomato, from wild ancestors to contemporary breeding accessions. BMC Genomics
2015; 16 (257)
2. Tieman D, Zhu G, Resende Jr. M, Lin T, Cuong N, Bies D et al. A chemical genetic roadmap
to improved tomato flavor. Science 2017; 355 (6323): 391-394
3. Silva E, Dawson J. Tomato Variety Trials for Flavor, Quality and Agronomic Performance, to
Increase High-value Direct Marketing Opportunities for Farmers and On-Farm Trialing
Capacity. Sustainable Agriculture Research and Education. 2016 Available from:
https://projects.sare.org/sare_project/lnc14-357/?ar=2016
4. Savidge, N. Chefs, farmers and UW scientists team up for flavorful produce. Wisconsin State
Journal. 6 Dec 2015. Available from:
http://host.madison.com/wsj/news/local/education/university/chefs-farmers-and-uw-scientiststeam-
up-for-flavorful-produce/article_633a2f89-01be-5a12-a237-98cbbef6a09d.html

This piece was featured in Volume III Issue I of JUST.

2017-12-12T23:56:23+00:00 December 14th, 2017|