Cream of the Crop Tomatoes

Sunday, November 4, 2018

Cream of the Crop Tomatoes – Extended Shelf Life XSLTM Tomato

Tomato fruit generally peak in flavor and texture at the “full ripe” stage.  Post-harvest deterioration is due to a number of natural processes that include fruit softening and dehydration, and infection of the fruit by post-harvest disease organisms.  In tomatoes shelf life is typically defined as the period of time between when the fruit is at full ripe stage and when the fruit deteriorates to the point of becoming undesirable.  Although many heirloom types only maintain good fruit quality for a matter of a few days, some improved types can maintain quality for several days longer.  

The ripening process in tomatoes is greatly influenced by the plant hormone ethylene.  Increased levels of ethylene in the plant promote both the positive changes associated with ripening, such as fruit coloration, sugar accumulation and production of flavor compounds – but also negative post harvest changes, such as fruit softening.  RIN (Ripening Inhibitor) and Nor (Non Ripening) are two master regulatory genes in tomato that control both ethylene production and numerous downstream ripening processes. Mutations in the RIN and Nor genes have been identified as candidates for extending shelf life in tomatoes.  The rin and nor mutants (alleles) cause a non-ripening phenotype in the inbred parent, but an extended shelf life phenotype in hybrids with a rin or nor inbred parent.

In our breeding program we have identified both rin and nor parent lines that, in combination with careful selection of conventional parents, provide for a fully flavored hybrid fruit with a very significant (14-21 day) improvement in shelf life.  We are using the XSL trademark and logo to identify our hybrids that have this extended shelf life trait.

fruit of wild type parent and XSL hybrid 35d after harvest

Sunday, July 16, 2017

Cream of the Crop Tomatoes

In 2015 A.P. Whaley Seed Company and Frogsleap Farm started a joint project on tomatoes.  Most large fresh market tomato breeding programs have focused primarily on three things: high fruit yield, shipping-friendly fruit, and disease resistance.  Consumers are demanding better flavor, and the larger companies are struggling to meet this new market demand.  On the other hand there are several small breeding programs with some excellent heirloom-derived O.P. varieties, but generally without broad spectrum disease resistance and new technology that enables extended shelf life.  We sensed an opportunity to combine modern breeding tools with a strong customer related focus on great tasting tomatoes.

Our strategy has been Flavor First.  The breeding program was started about a decade ago by making crosses between our favorite heirloom types (e.g. Cherokee Purple, Brandywine and Kellogs Breakfast) and some of the best tasting striped varieties (e.g. Berkeley Tie Dye, Black Zebra, and Pink Boar).  Sungold, everybody's favorite hybrid cherry, was added to the crossing mix.    During several generations of selection in various breeding nurseries, new lines from these crosses were selected for outstanding flavor, improved plant health, earliness, good fruit yield and high fruit quality.

A few years later the best F4/F5 lines were crossed to a few commercial hybrids with outstanding disease resistance, excellent fruit quality and/or extended shelf life.  Marker assisted selection (MAS) was then employed to effectively concentrate the resistance alleles in segregating progeny – combined with tasting and selection each generation to keep flavor in the forefront.

An example of disease resistant and FLF high flavor parents

The backbone of the breeding program has always been our large breeding nurseries in North Carolina, Pennsylvania and Wisconsin, within which there has been rigorous selection for plant health (biotic and abiotic stress tolerance), fruit quality (tolerance to cracking/splitting and fruit texture), fruit yield and fruit flavor.  By design - tough selection environments, and tough parent lines with extraordinary flavor.

Pennsylvania breeding nursery

North Carolina breeding nursery

2017 Trials and Nursery at Whaley Farm in Mt Horeb, WI

We have multiple target markets: home gardeners, small/medium sized open field commercial producers targeting value-added markets, and small to large scale high tunnel/greenhouse producers.  We will strive to develop products ideally adapted for each of these markets.  Our breeding program includes tomatoes of all sizes and shapes and in every imaginable color, many with gold or green stripes.

Most of the products released by Cream of the Crop Tomatoes will be F1 hybrids.  We have identified parent lines with general and specific combining ability for both fruit yield and flavor.  The increase in fruit yield for F1s was expected, the magnitude of heterosis for flavor was a pleasant surprise.  A hybrid scheme also greatly facilitates stacking of multiple disease resistance traits and is a requirement in deploying some of the extended shelf life alleles for genes controlling fruit ripening.

To achieve our commercial goals we have invested in a state of the art breeding program, with an experienced breeding team using traditional and marker assisted breeding, coupled with year round greenhouse capabilities to enable multiple generations per year.  We are also expanding collaborations to increase our ability to test new products in various open field and protected culture production systems.

Collecting tissue samples for marker-assisted genotyping

Cream of the Crop Tomatoes – Extended Shelf Life XSL TM  Tomato Tomato fruit generally peak in flavor and texture at the “full ...