How do you know your cross is a success?

[kevokie]

So, like the topic says, when you make a cross between two plants, how do you know that the cross is successful? I assume practice makes perfect and you just "know". You would also know later if crossing a PL and RL.

Ok, enough beating around the bush. Someday, I'm planning on crossing two RL plants. One is a striped tomato, and the other is a red oxheart tomato. I assume that I would have to wait for the fruit from the F1 to set before I knew exactly if the cross took? Maybe I'm getting in way over my head, but who knows. Thanks

Kevin

[Raymondo]

Exactly right, you'd have to wait for fruit if you're crossing two RLs to know. This assumes they're different enough to tell. Sounds like yours will be.

[Tom Wagner]

How do you know your cross is a success?

Kevin writes;

So, like the topic says, when you make a cross between two plants, how do you know that the cross is successful? I assume practice makes perfect and you just "know". You would also know later if crossing a PL and RL.

Successful Cross? I certainly agree that practice makes perfect, and the "know" is questioned even by an experience breeder as myself. I spent the greater part of this week looking at hybrid seedlings of both tomatoes and potatoes, parsing over visual characters as to the veracity of a cross.

I suppose I should do a systematic exposition or argument in writing including a methodical discussion of the facts and principles involved and conclusions reached about crossing. That someday isn't now, however.

It all starts with a timely emasculation effort on the flowers before the anthers shed their pollen. It follows with one or more applications of pollen at the beginning day of the cross followed (if possible) by a repeat pollination a day or two later.

I prefer to do a cluster cross rather than a single flower cross. My odds go way up when I do this. Long story about this isn't now either.

I like to save seed from the same mother plant as the cross for reference purposes. When I really want to know if the cross "took" I sow almost immediately a triad of the cross and both of the respective parents. As the seedlings emerge I look for major, minor, diminished, or augmented trait differential notes. If you "hear" the music chords about now, you "know" the cross took.

How old do the seedling plants have to be before you recognize affirmation? Depends. Continue on...

Ok, enough beating around the bush. Someday, I'm planning on crossing two RL plants. One is a striped tomato, and the other is a red oxheart tomato. I assume that I would have to wait for the fruit from the F1 to set before I knew exactly if the cross took? Maybe I'm getting in way over my head, but who knows. Thanks

Yeah, crossing two regular leafed tomatoes makes for a more difficult proof of the cross, such as between potato leaf and regular leaf. Nevertheless, your choice of a striped tomato and a oxheart type is advantageous for this juncture. The wispy, long, and narrow leaves of an oxheart tomato will be evident in a cross with a striped tomato as long as it isn't Banana Legs, Striped Roman, Green Sausage, or some other narrow leaf striped tomato line.
The direction of the cross should not matter, as the hybrid leaf pattern should be showing nicely in about 4 weeks or less after sowing. If you take digital photos of the cross compared to the parentals, you should see the incomplete dominance of the leaf shapes.

There are a whole host of other morphological traits that one could see within about 8 weeks of sowing but that is for another time.

That book ain't been writ yet.

Tom Wagner

[Vince]

I just started some sungold F1 X Cherokee Purple I crossed this fall. In this case I guess you would expect the resultant F1 not to look homogenous. What Tom just suggested ...

"I like to save seed from the same mother plant as the cross for reference purposes. When I really want to know if the cross "took" I sow almost immediately a triad of the cross and both of the respective parents. As the seedlings emerge I look for major, minor, diminished, or augmented trait differential notes. If you "hear" the music chords about now, you "know" the cross took".

is an excellent idea, but in this case the most useful information for my cross would come from growing the uncrossed sungold F2 seed for comparison. I Really wish would have saved some uncrossed sungold F2 seed, oh well. If Any body has any other suggestions about how to tell if the cross I mentioned took, please let me know.

Thanks

Vince

[Tom Wagner]

I just started some Sungold F1 X Cherokee Purple I crossed this fall. In this case I guess you would expect the resultant F1 not to look homogeneous.

Yes and No. Anytime one would use a stable variety such as Cherokee Purple in a hybrid, there is a "blanketing" effect on the resultant hybrid seedlings. By "blanketing" I mean that offspring share a morphologically similar appearance. The other parent, an F-1 Sungold, will throw a strong cherry tomato foliage, since both of its parents are cherry types. So what you will be looking for is that "look" that is not quite cherry but certainly not like the leaf types of a large fruited tomato like Cherokee Purple.

...in this case the most useful information for my cross would come from growing the uncrossed Sungold F2 seed for comparison. I Really wish would have saved some uncrossed Sungold F2 seed, oh well. If Any body has any other suggestions about how to tell if the cross I mentioned took, please let me know.

I have saved seed from the F-1 Sungold and F-1 Sun Sugar to self out more uniform candidates for crossing. I still see the cherry leaf habit in the F-2 population and I have a fair amount of experience crossing the original hybrids and selfed lines of both tomato varieties.

What to look for? Flatten leaf shapes, not the dipping, rolling, large lobed tomato leaves of a Cherokee Purple. You might look for the serration habit, the veination, and overall color of the green leaves at the second and third true leaf stage. Later on you will see stem differences, auxiliary stem formation, on up to the first flower buds, which will look more like a cherry tomato flower than the larger Cherokee Purple flower size.

Last year I looked at hybrid seedlings of several hybrids like what you have made.

Sun Gold OP X Matchmaker
Sun Gold OP X Jubilee
Agate Grape X Sun Sugar OP
Greenwich X Sun Sugar OP
Sun Gold F-1 X Stupice
Sun Sugar F-1 X Stupice
Sun Gold F-1 X Waterstone
Debaro X Sun Sugar OP
Pectin Grape X Sun Sugar OP
Garden Lime X Sun Sugar OP
Green Zebra X Sun Gold OP
Stripes Forever X Sun Sugar OP

Each of these appeared correct at the seedling stage and were validated at harvest time as well. This year many of those are in F-2 populations and F-1 populations of F-1/F-1 hybrids, which greatly complicates the issue.

As far any further suggestions to Vince, some photos posted might help tremendously, and that includes top views as well as side views of the seedlings.

Tom Wagner

[amideutch]

Tom, 2 questions.

1. What was the origin of your Sungold OP?

2. What is your criteria after you select the crosses you want to make as far as which variety will be the "Donor" and which will be the "Mother" or does it matter? Thanks, Ami

[Raymondo]

Fantastic. I've learned a lot from this thread. Thanks Tom, and thank you to Kevin for posting the original question.

[Tom Wagner]

Ami,

The Sun Sugar OP and Sun Gold OP that I mentioned are just some segregated lines that are several filial generations away from the hybrid plants I had a number of years ago. I wanted to lock in whatever traits that I found and wanted for further breeding and variety development.

As to the second question, it doesn't make a whole lot of difference to me which variety is the pollen donor. I do, however, prefer to use as the female plant one that carries a lot of recessive traits that 'lose out' in the hybrid. Makes it easier to see if the cross took in the seedling stage. Examples are dwarf, jointless, determinant, stripes, woolly, male sterile, potato leaf, wispy leaf, prostrate vine habit, non-ripening genes, sepal size, petal color, etc. The more I can see due to the efficiency of the cross, the less I have to wait until the plant blooms or even grows an immature fruit.

I don't make enough pre-determined directional crosses since I kinda like the serendipity or gut feelings that happens when I take the time to cross.

I will be making crosses soon since my Feb. sowing tomato group is showing a few early bud formations. In this case, the crossing will commence with early blooming traits dictating the first round of crosses. It appears that the frost resistant lines are beating the others to the blooming stage since my plants are in an unheated greenhouse and the temps outside are still dropping into the mid thirties.

If anyone learns anything from the drivel I write, you must be reading between the lines.

Tom Wagner

[Raymondo]

A few questions please Tom. Does jointless refer to the stalk to which a fruit is attached? And what are the dominant/recessive characteristics of sepal size and petal colour?

[dice]

For crossing a cherry with a non-cherry where both are PL
or both are RL, I would make the cherry tomato the pollen
donor and the non-cherry the female parent, for two reasons.

One is that cherry size is dominant, and if nothing else you
should be able to tell from the size of the first F1 fruit whether
the cross took. (If the fruit of the F1 is the same size as the
non-cherry parent, the cross probably failed.) The other reason
is that you probably get more seeds of a successful F1 cross
from a fruit of the larger fruited parent than from a fruit of
the cherry tomato parent. (Not an absolute truth; some larger
fruited cultivars have very few seeds per fruit.)

If the cherry has lots of recessive traits aside from size, like
those Tom mentioned, then maybe do it the other way around
and not have to wait for fruit to know whether the cross took.

I would guess that larger flowers are easier to emasculate
successfully at the bud stage, too.

[Tom Wagner]

Thanks, Dice, for bringing up your points..

The other reason
is that you probably get more seeds of a successful F1 cross
from a fruit of the larger fruited parent than from a fruit of
the cherry tomato parent. (Not an absolute truth; some larger
fruited cultivars have very few seeds per fruit.)

Seems to me that nothing is simple and straightforward when it comes to crossing platitudes.

It depends on the ampleness of pollen gathered. If one can collect more pollen from a cherry type versus the large fruited type for the cross, that very detail will afford a good seed set. The smaller head (stigma) on a cherry flower needs less pollen to effect good pollen fixation.

Cherry flowers seems to be quicker on developing a fruit after crossing sometimes, and ripen earlier. I can do more crosses on a cherry tomato vine than a large fruited type since only so many fruit seem to want to take on those.

Some cherry tomato varieties set lots of seed and are less apt to drop due to abscission under stress.

Emasculating some cherry tomato type are extremely difficutlt, so for a novice a large fruited flower is sure easier to avoid anther extraction accidents.

Raymondo asks:

A few questions please Tom. Does jointless refer to the stalk to which a fruit is attached? And what are the dominant/recessive characteristics of sepal size and petal colour?

Fruits harvested from wild-type plants (read normal tomato varieties), retain the calyx and the distal end of the pedicel, whereas jointless fruits are "stemless" when harvested. This characteristic is very common for mechanically harvested fruit. The jointless mutation does not affect other abscission zones, such as those of leaves, style, or corolla. You know you have the jointless trait when you go to pick. One grabs the tomato into the palm of his/her hand and uses the thumb nail the position at the stem juncture to more or less, clip the tomato free. With the jointless trait you have to cut the stem or break the stem clean away from the fruit.

I use the jointless trait to confer (On the Vine) cluster picking to many older heirloom type tomatoes. I can get more blemish free, longer laster tomatoes to the table or market.

I use primarily the j-2 gene, which is located on chromosome 12. The other jointless gene, j-1, is on chr. 11.


Now all this talk is not without consequences. The j-2 gene may cause, in some tomato pedigrees , significant yield reduction. But, it was demonstrated in isogenic studies that this gene couldn’t exert any important pleiotropic influence on any of the processing characteristics evaluated. So go figure! Wait a minute, you might ask, what the @*&% does pleiotropic mean? Should I define the term? Yes, No? OK, enough with the glazed eyes, already!



Here is a quote from the Internet:

Pleiotropy occurs when a single gene influences multiple phenotypic traits. Consequently, a new mutation in the gene will have an effect on all traits simultaneously. This can become a problem when selection on one trait favors one specific mutant, while the selection at the other trait favors another mutant.

A definite association between jointless pedicel and node number leading up to the first flower cluster. There are often leaf bracts associated with some jointless lines around the inflorescence (flower cluster).




In nearly every case of mutations one needs to look for disadvantages of gene substitution. Jointless tomato varieties seem to be more prone to catfacing than jointed varieties, according to a Maryland study. I do not, however, support that observation 100%. If I had to offer my objections and exceptions, I would be here all day typing!



Sepal size, shape, counts, etc., is something I am using more of in my crossing and segregation studies. Excellent use as most are quite recessive. And many of these sepal characteristics are linked with other desirable traits.



Petal color. The Old Gold color of high lycopene varieties have this color rather than the standard yellow flower petal.
Also a good recessive. I like to add the og gene into all kinds of heirloom bloodlines.

As a plant breeder, I tend to like to slam a whole bunch of recessives into a single clone for introgression works, ie og, rin, j-2, triple fusarium res. ve, stripes, different flesh colors, and so on. That way almost anything that I develop will have no look-a-likes out there to be confused with.




Most of what I am talking about, since my writing is close to talking, supports my contention that the female parent in most crosses should be the most recessive laden variety of the hybrid seed bulking. With a quick germination study immediately afterwards of picking the fruit and lasting just a few weeks, this effort will prime the next year's seed dissemination without qualm as to the proof of F-1 status.



Tom Wagner

[Raymondo]

Thanks Tom. Much appreciated.

[Vince]

In reply to Tom,

"As far any further suggestions to Vince, some photos posted might help tremendously, and that includes top views as well as side views of the seedlings"

The seedlings are just at the first leaf stage, so I will wait a few days to post some pics. Thanks for your help.

Vince

[Vince]

OK Tom, here are some pics of the sungoldXCP seedlings. The three big ones look almost identical. The two runts look a little sickly and different. So from these pictures can you tell if the cross was succesful. Thanks for your opinion.

[Vince]

just bumping it up