Sunroot and Sunflower Crosses

[starry]

Excerpted from 'Progress in breeding perennial grains' from the Land Institute www.landinstitute.org/pages/progressperennial.pdf

"The parallel route to perennial sunflower is through hybridisation. Domestic sunflower, a diploid,can be hybridised with several perennial species in its genus, including Maximilian sunflower and two hexaploids: rigid-leaf sunflower [H. rigidus (Cass.) Desf.] and Jerusalem artichoke(H.tuberosus L.). Hybrids between annual and Maximilian sunflower are highly sterile. The strategy we have followed in producing perennial, partially fertile plants involves crossing both annual and Maximilian sunflower to H. rigidus and H. tuberosus to produce tetraploid plants, which we then inter-pollinate. Large perennial populations thus produced are now undergoing selection for greater seed fertility. In 2007, 102 interspecific hybrid plants produced more than 100 seeds each, and 26 produced more than 500 each. Those are small seed numbers compared with the annual parent, but large compared with most such hybrids. "

This supports what you were saying agrorev. 


Looks like large scale planting and selection is the key to fertility.

I have been reading through a few papers from the Land Institute...they are doing some really cool stuff!

[starry]

I have 5 varieties of Sunroot ('Clearwater', 'Stampede', 'Skorospelka', 'Passamaquoddy Potatoes' and one unknown variety) that I will be attemtping to cross with various sunflower varieties this coming growing season. I think I'll grow them in pots like Paolo (on the facebok group) has been doing.
It was really interesting to learn that Stampede is day neutral as well.

[nicolas]

What are your plans for your future crosses ? What cultivars of sunflowers ? Do you know any cultivar of sunchoke that are more fertile than the average ?

[agrorev]

Peace Seeds offers a Helianthus annuus x H. argophyllus mix called "China Cat Sunflower." Not sure how it may effect the project, but seems a good idea to add as much diversity as we can into the sunroot x sunflower F1s initially.  


On the other hand, if we are trying to hone in on the seed/flower qualities of the sunflower, we probably should not use such a mix.  It could overcomplicate things.  But I still wonder, would there be greater or sustained hybrid vigor among the offspring of such a hybrid [H. tuberosus x (H. annuus x H. agrophyllus)].

[nicolas]

For my part, because you drove me into this anyway, i still search for good cultivars of sunflowers. I hesitate between cultivars breed for snack vs ons breed for oil content. Size is less a concern in the second case so maybe ...
I've read in one of Joseph articles that hybrid sunflowers are usually affected by cytoplasmic male sterility so i'll stick with open pollinated.


I need to find fertile sunchokes cultivars too. I've some cultivars but havent yet looked if there were fertile. I plan also to try H. strumosus in place of the tuberosus because i think it is more fertile based on a comment of a nursery. But its just a guess. Maybe it will help to diversify the mother of the F1 to try crosses between the F1s (as it appears to be the best strategy to restore fertility if i've understood correctly).

This is a great community project because one has interest in sharing the hybryd offsprings to have the maximum genetic diversity.

[agrorev]

Peace Seeds OP sunflower seems like a good place to start. I don't know about the fertility of sunroots, but I've heard that do they make seed if there are more than one variety around. Maybe their fertility is underestimated in this way, or maybe their fertility has been decreased through clonal propagation (or both?).  I haven't grown enough sunroots to evaluate this, but fertility shouldn't pose a great obstacle for them since we know at least several types do make seed.  Late flowering would be another thing depending on variety/location.  I personally would be inclined to use tuberosus as the seed parent because I'm curious as to what could be the tuber palatability of the hybrids. 

[agrorev]

Also this would be a prime experiment to evaluate Michurinian selection theory/graft hybridization. The F1s should be highly influenceable with their new chromosome numbers and heterozygosity. If we graft the F1s to a robust dahlia or yacon, or a contrariwise a yacon onto a new hybrid, then per Michurin we would see a deviation on the form of the hybrid to the yacon/dahlia/other relative.

[starry]

I haven't really thought too far into the future other than to get the 5 different sunroot and sunflower crosses.
Sunroots are not self fertile but by using 5 different sunroots I hope to increase the chance that I can cross them to each other in the second generation.
Once the initial crosses are made I should at least have some perennial sunroot x sunflowers that I can perpetuate and play with down the road.
If I can get seed from these I will hopefully have lots to share for others to play with.

[agrorev]

Sounds good Fruit Snacks. The is an interesting example of an easily obtainable (fairly) wide cross. I think you'll have good luck. I will attempt it also if I'm in town and the timing works out. I do plan on evaluating the graft hybrid ideas with this cross, as I've been very curious to but haven't had the time it takes to do such work with fruit trees. This year I'll grow out some of the China Cat Sunflower mix from Peace seeds. Sunchokes I have are stampede, white fuseau, and supernova (doesn't flower).

[nicolas]

A very good resource :

Evaluating an interspecific Helianthus annuus × Helianthus tuberosus population for use in a perennial sunflower breeding program

Field trials indicated that seed yield traits were positively correlated with head
traits. Tuber traits, which are required for perenniality, and seed yield traits were not
correlated, indicating that simultaneous selection may be able to target high yielding lines
that also tuberize. The F 1 individuals were intermated for one generation and the
intermated F 1 (IM 1 F 1 ) showed increases in head size (up to 20%) compared to the best F 1
individual. The lack of correlation between tuber and seed traits coupled with phenotypic
improvement after one generation of intermating suggest that the best improvement
strategy for perennial sunflower is a recurrent selection program focusing on yield.


Helianthus tuberosus (2n=6x=102), is an autoallohexaploid
with three sub-genomes. The three sub-genomes have been traditionally designated as A 1 ,
A 2 , and B t (Kostoff, 1939). The B t sub-genome is thought to be very similar to the H.
annuus genome (Kostoff, 1934; Kostoff, 1939; Scribria, 1938), which may help stabilize
meiotic chromosome pairing in interspecific hybrids between the two species.


H. annuus x H.
tuberosus hybrids generally have a stable intermediate number of chromosomes
(2n=4x=68), although meiotic abnormalities can reduce fertility and decrease stability in
initial generations



F 1 plants typically flowered earlier than H. tuberosus. The F 1 hybrids were not statistically different from H. tuberosus for spread ability but
were for branching type. F 1 plant spreading and head number varied greatly between
environments. Hybrids displayed fewer total flowers, but not the single head type preferred in H. annuus cultivars. Three tuber traits were examined: tuber number, total
tuber weight and individual tuber weight. The F 1 hybrids had greater tuber number,
individual and total tuber weight than H. tuberosus. Head size exhibited a wide phenotypic range both
within plants and among families. The largest heads among the F 1 individuals were 5-6
times bigger in diameter than H. tuberosus (Figure 2-3). The majority of F 1 plants had
few seeds (0-25), yet some individual F 1 plants yielded ten times this amount. There was
differential shattering or predation among environments that likely increased seed yield
variability.


F 1 individuals were intermated to generate an IM 1 F 1 population. We continued to
observe improvements for yield traits in this generation, despite the absence of artificial
selection pressure in choosing parents for the IM 1 F 1 . However, differences in pollen
fertility may indicate that inadvertent selection for viability of pollen occurred. Three plants were ranked in the
top 10% for largest head diameter, seed weight, and seed per ten head for the IM 1 F 1
population. The largest head was 20% larger than any head observed in the F 1 . Positive
correlations between head size, seed weight, and seed per head were maintained. The best
IM 1 F 1 individuals exhibited numerically higher values than the best F 1 individuals for all
seed traits, indicating the potential power of a recurrent selection program. While all F 1 individuals exhibited perenniality through tuber sprouting, the IM 1 F 1
population segregated for the perennial habit. In the winter of 2009-2010, 71 plants were screened for winter survival with 77% (55) surviving


Based on our investigation, we found that when F 1
plants (tetraploid) were crossed with H. annuus plants (diploid), weak annual triploid
plants were generated. Therefore, we refocused our efforts on selection and intermating of the best F 1
individuals. Furthermore, wider ranges were observed in the IM 1 F 1 compared to the
F 1 for some traits, indicating that recurrent selection on intermated materials may
successfully take advantage of the wide genetic variation for further improvement.

our breeding design is unique in that it uses interploidy
hybridization and maintains the populations as polyploids. The ability to drive the
phenotypic traits toward the ideotype using our intermating scheme will depend on the
rate at which the H. tuberosus genetic material can be purged from the genome (and
replaced by the H. annuus genetic material), while maintaining perenniality. There are
two factors that will determine this limitation: 1) The amount of H. tuberosus genetic
material that is required for perenniality and 2) The meiotic pairing behavior of
homeologous chromosomes.


In the present study, all Helianthus F 1 plants were
perennial and the IM 1 F 1 population segregated approximately 3:1 for tuber production
with tuber survival (over-wintering ability) differing among seasons.


The
intermating (IM 1 F 1 ) approach exhibited the greatest potential, as domestication traits
were improved in the IM 1 F 1 while maintaining perenniality in a high proportion of the
population. The improved phenotypic traits in the IM 1 F 1 may be indicative of the loss of
wild chromosomes or portions of chromosomes in favor of domestic chromosomes.
Therefore, recurrent intermating and selection of advanced intermated lines appears to be
a promising approach for further improvement. Perenniality may segregate in a relatively
simple way even if the underlying genetics are complex. Our data indicate that we have
started our program with limited diversity, but despite this we have seen gains in initial
generations

[starry]

Great post nicolas. Sounds like the strategy I was going to attempt will have a good chance of success.

[nicolas]

Yes, the important thing is to mate between F1s (and following generation) and not to try to backcross with sunflowers.

[MikeH]

Biology and Chemistry of Jerusalem Artichoke

[paolog]

While it is true that the majority of F2 plants are sterile, if I remember correctly a single very fertile specimen out of a few hundred sterile ones was found. It's not really a dead end, but simply a matter of big numbers.
There are some very productive supposed H. tuberosus varieties that always puzzle me for their high sterility and unusual tuber shape. I'm under the impression that these are really interspecific hybrids...
Another possibility is that they self-pollinate too quickly to allow different pollen in and thus are "physiologically" sterile..

[agrorev]

Paolo, the F2 you mention is the backcross to either of the parents? Getting fertile lines among the tetraploid F1s themselves doesn't appear too difficult.


Nicolas, thats a great resource indeed.  So the largest flower head of the F1s was 5-7 cm, and in the next generation already they improved this by 20%...not bad!