Frogsleap Farm

Frogsleap Farm

Saturday, January 25, 2014

Hybrid vs O.P. tomato varieties

Tomato hybrids are F1 crosses between two stable inbred lines.  Since tomatoes are primarily self-pollinated, O.P. (open-pollinated) varieties are stable inbred lines – with perhaps a little variability from low level chance outcrossing.

The vast majority of all of the commercial tomato production in the world is with F1 hybrids, whether the hybrids are designed for processing or fresh market use.   Higher fruit yield in F1 hybrids is probably the biggest driver here, but stacking disease resistance genes is another benefit.  Since most commercial breeding companies are breeding for traits other than flavor – most F1 hybrids, with a few outstanding exceptions, are lousy in that regard.

Heirloom types, developed over many generations by families and/or communities, have been selected primarily for flavor.  These are all O.P. types, though I know there are some companies talking about heirloom hybrids - heirloom x heirloom I suppose.  Heirloom varieties typically have their own set of challenges: low yield, disease susceptibility, short shelf life, and/or fruit quality (cracking/catfacing, etc.) problems.

In the last several years several breeders have begun crossing commercial hybrids with heirloom types to get the best of both worlds – but that’s a different story.

As a tomato breeder I see intrinsic advantages in F1 hybrids – some obvious, others not.

Hybrid vigor or heterosis.   This is usually simply defined as performance in the F1 that is better than either of the parents.   Numerous scientific studies report and commercial tomato breeders have demonstrated the potential for heterosis for fruit yield, and there is substantial evidence of heterosis for other
traits (reference; pages 115-127), including sugar and acid content - key drivers for flavor (reference).  We make several dozen new F1 crosses every year and in many cases we see exceptional flavor in the F1 generation that we never successfully stabilize in succeeding filial generations.  Several years ago my friend Bill Jeffers sent me seed of a F1 cross he made (Indian Stripe x Sungold).  Flavor in the F1 generation was out of this world, and to our mutual disappointment we were never able to capture anything close to this in F5/F6 lines.  Another breeder friend Keith Mueller has commercialized the F1 hybrid “Purple Haze” derived from a cross between Black Cherry and a (Brandywine x Cherokee Purple) line he developed.  He says that this specific combination demonstrates heterosis for flavor that stands out from other similar crosses he tested.  I am confident there is heterosis for flavor in tomato, but realize it will require a lot of test crossing to identify parents that fully capture this.

    Stacking disease resistance traits.  Wild relatives of tomatoes have been a rich source of genes for resistance/tolerance to key tomato diseases.  With few exceptions these disease resistant genes are inherited as dominant alleles – e.g. Resistant x Susceptible = Resistant.  In a F1 hybrid typically one parent will be resistant to one set of diseases (e.g. ABC), the other resistant to another set of diseases (e.g. DEF) with the hybrid then resistant to both sets of diseases (e.g. ABCDEF).  This has proven to be a very effective way of stacking disease resistance in tomato varieties.

Some genes are desired in the heterozygous state.  In inbred (i.e. O.P.) lines the plants are homozygous at virtually all loci.  For a particular gene/locus the heterozygous condition is only possible in a hybrid, or an unstable segregating population.  The recessive rin allele is involved in fruit ripening.  In the homozygous state the fruit never ripens, in the heterozygous state (rin/+) there is delayed ripening of the fruit, providing extended shelf life.  Many of the vine ripened tomatoes (cherry, grape and cluster) now being marketed in grocery stores are rin/+ F1 hybrids.  The NC State rin/+ hybrid Mountain Magic is an excellent example of a tasty tomato with exceptional shelf life (and state of the art multiple disease resistance).   More recently a discovery was reported that a loss of function mutant allele in the gene SFT, which codes for the flowering hormone florigen, had a profound effect on plant growth in tomatoes.  Homozygous sft/sft plants had significantly delayed flowering and low yield, heterozygous plants sft/+ (in determinate plants)  had 60% higher yield (photo above) and enhanced flavor (reference).

New F1 hybrid (Aft/+)
Complementary traits.  Some of our best inbred lines absolutely nail some traits (e.g. flavor and/or fruit type), but have one or more key weaknesses (e.g. splitting, poor seed yield, late fruiting or plant architecture).  By selecting hybrid parents that compliment each other for key traits, we’ve identified F1 hybrids that are clearly superior to the parents.  This is perhaps another ramification of the heterosis discussion above.

There are only two disadvantages of hybrids vs O.P. varieties that I can think of:  a) seed production is more complicated and more expensive.  Related to this grower saved seed is not an option, and b) a significant portion of the customer base for tasty locally grown (homegrown or farmers markets) fresh market tomatoes has an anti–hybrid bias, unfortunately often confounding F1 hybrids with GMO traits, organic vs conventional, or big biz vs family owned operations. 

Frogsleap Farm is a two person husband and wife breeding team, working with the best heirloom and commercial hybrid germplasm we can find, and developing novel varieties (including F1 hybrids) for both organic and conventional producers.   We think both F1 hybrids and O.P. varieties will have a place in an exciting marketplace of unique and tasty tomato varieties adapted for use by home gardeners and small to medium sized tomato producers.

Saturday, October 19, 2013

News from 2013

Cross to commercial F1
It seems like every year there is an 
epiphany in our tomato breeding program that logically sends us in a little different future direction.  Here are a few things we learned this year.

Fruit quality (crack/splitting resistance, lack of catfacing, and improved shelf life) and excellent taste are not mutually exclusive.  We now have several lines derived from heirloom x commercial hybrid crosses that appear to be combining the "best of both worlds".  We've made the greatest progress in saladette, grape and cherry types.

As in most parts of life - you don't know what you don't know.  Everything I thought I knew about fruit color, stripes, and shape - is more complicated.  We are finding unexpected and wonderful combinations of skin/flesh color combinations, patterns of striping, and fruit shape.  The photos below show some of these interesting combinations.

New F1 - green striped w/ red flesh
Orange skin - green flesh
Wonderful stripes - green flesh
red stripes on yellow?
Racing stripes and great flavor
Broad metallic green stripes

Blood red flesh w/ metallic stripes
elongated pear
Bowling pin
derived from Lucky Tiger
Odd trait combo on all fronts

interior of above
Super sweet ugly duckling
Piriform w metallic stripes
New striped heart

I think we have been working with the so called "blue tomato" germplasm as long as anyone outside OSU - where it was invented.  Although there have definitely been some cool looking tomatoes coming from our various crosses (and those we've evaluated from others) - taste has been disappointing.  We continue to backcross the Aft and atv genes into our best tasting lines, and we are finally making progress in flavor
One of our selections from Muddy Waters
One of several indigo striped cherry lines
An indigo version of Freckled Strawberry
Taste test winner this year - a new F1
The elusive Bengal Tiger
In spite of some weird weather - too cool and wet then too hot and dry - we had a great year in our MN and PA breeding nurseries.  We hope to ramp up the breeding program next year with more nursery locations to help in the evaluation of the few hundred FLF breeding lines now in development.

Saturday, March 2, 2013

2012/13 F2 growouts

Every summer we make at least a few dozen new crosses as "breeding starts"; new F1 seed from which to make selections in the F2 and following filial generations.  The goal is to pick F1 parents with complimentary attributes, from which F1 we can hopefully eventually develop stable OP lines combining the best qualities of each parent.  Unfortunately only a small percentage of new breeding starts actually end up producing the exceptional new variety you had in mind when you make the cross - but such is the nature of plant breeding.

With some great help from a friend, this winter we were able to do greenhouse growouts of a handful of new 2012 F1 breeding starts from which we collected F2 seed for 2013 summer selection nurseries.  Here are a few photos.

Chocolitos w/ anthocyanin stripes

A key commercial hybrid x tasty striped cherry

Adding stripes to Tasti=Lee

A tasty salad type w/ anthocyanin stripes

A very tasty GWR cherry w/ anthocyanin stripes

Improved flavor in a red cherry w/ Aft + stripes

Another Striped Chocolitos x Aft

Tasti-Lee x striped cherry

Exceptional flavor w/ improved disease resistance

A new striped heart in the making

Another striped heart cross
A nippled red grape - painted w/ gold

Saturday, November 17, 2012

2012 Highlights

We had a great breeding year.  We continue to fine tune our best lines as they approach genetic stability, identify exciting new lines in large F2/F3 segregating populations, and create breeding starts with new F1 crosses.  Here are some photos from our breeding nurseries in Minnesota, Pennsylvania and California.  They all taste at least as good as they look.

Very unusual exterior/interior color combo
A new F2 - I love the shape/color

A new striped heart

BZD - a large striped cherry with deep red flesh 

One of several new crosses w/ Tasti-Lee

Looking for a GWR striped indigo cherry

F2 sibs in Penna

Golden Grape x Captain Lucky F2

A great new striped heart w/ crimson flesh

Fabulous flavor/great shelf life in this F3

A F3 sister line from the same cross as photo above

Fred Hempel's Green Day

Striped indigo cherry

Stripes and black streaks???


Mark in Penna nursery

Michael Pollan x Cowlicks Brandywine F2 sibs

Our selection from Tom Wagner's Muddy Waters

I love this pattern

A FLF/Baia Nicchia F1

A nice surprise inside

A new striped indigo variant

Stable now - striped Sungold

Striped Piccolo F2

A F1 hybrid striped grape
Freckles and stripes

Two F3 sibs - both w/ bright green flesh

Pandora's Box