Perennial grain sorghum

[walt]

The Land Institute, Salina, KS, USA, has been breeding for perennial sorghum for 35 years, and have made some success.  But no varieties or breeding stock has been made available to the public.  And none will be released soon.
But when I visited with Dr. Stan Cox a couple of days ago. he gave me seeds of a tetraploid grain sorghum, that is public domain.
Tetraploid domestic sorghum crosses easily with Johnsongrass, a perennial weed, and the hybrids are fertile.  So I'm once again a sorghum breeder!
I'll keep you up to date on this.  If anyone is interested in joining this project, seed will be available at each step of the way.  Seed will not be useful for several generations, though.

[reed]

Wow, turning Johnson grass into food! I about jumped off my chair reading that. Then I realized, if the sorghum readily crosses then the hybrids likely would also. Because of that, the Johnson grass forests that are spreading across my neighborhood would soon overwhelm any project I attempted.

[walt]

Yesterday at the Land Institute, there were public tours of the research plots.  
The perennial grain sorghum plants were quite diverse.  With grain sorghum X Johnson grass you would expect that.  But they tended to be tall with loose heads.
Johnson grass seeds run about 2-3 mg each.  Domestic run 20-30 mg.  Until this year, the hybrids were in the single digits.  But this year 6 breeding lines broke into double digits. 
Kernza intermediate wheatgrass is being grown and used commercially now.  I don't know how many of us were at the Prairie Festival but we were each allowed 2 big pancakes with butter and Candaian maple syrup  The pancakes were made from Kernza flour.  Very good.  Kernza is being used commercially in muffins, beer, and a few other things commercially.  It is the first perennial grain to go commercial, that I know of.
On display were large plots of just Kernza, and Kernza and alfalfa in alternate rows.  The Kernza-alfalfa combination is yielding about 70%  as much grain as the pure Kernza, but Kernza is usually grazed after seed harvest.  So cattle would be eating both the Kernza grass and the alfalfa.  It is hard to figure out exactly how it compares economically.  Plots just like these are being replicated in several states and several countries.
They have started breeding Alfalfa (Medicago sativa) X Medicago arborea.  M. arborea seeds are 10 times the mass of M. sativa.  It is being looked at as a high protean food or food additive.
They have stooped breeding perennial sunflowers and substituted Silphiums as a perennial oilseed crop.

[fliver]

Did they say which Silphium they were using?

[walt]

I don't recall them giving the scientific name.  As I remember them, the leaves were not as big and compass plant.  I didn't see the cup of of cup plant (or is it pitcher plant).  I have never tried to get to know the silphiums. 
I do recall that they aren't crossing species, though the silphium species do generally cross and have some fertility in the hybrids.
I do recall years ago eating siphium seeds.  I picked a head in the pasture and quickly ate a few seeds.  The kernals were about the size of domestic food sunflower kernals, but easier to de-hull.  Long time ago, but it seems they didn't have hulls.
Silphiums are much longer lived than perennial sunflowers.

[walt]

A few weeks ago I potted up a couple of pots of Johnson grass rhizomes.  I put them inside hoping the warmth would start them growing.  I want to get some F1 seeds by spring, though I doubt I will. 
I am suprised that one is making a head now, making a head on a stem that is only about 1' tall.  I supose it is daylength that is rushing it along.  Or possibly transplant shock, but I doubt it as I transplanted 6 inches of bare rhizome.
This head will not cross with the tetrploid grain sorghum, as the grain sorghum is still at the 1 leaf stage.  But I expect repeatedly cutting off the head of Johnson grass will stimulate branching and new heads.  That works for grain sorghum.

[walt]

I just got the latest issue of The Land Report, the quarterly journal from the Land Intitute.
".....in 2014, 3/4 of 165 new hybrids looked much more like crop plants.  So did their offspring.  And genetic testing that - for reasons not yet fully understood - these new hybrids were diploids."
This makes perennial sorghum breeding much easier for 3 reasons.  1. Now about any of the world's domestic sorghum varieties can be crossed with perennial sorghum.  2. Diploids segregate 1AA:2Aa:1aa.  Tetraploids segregate 1AAAA:8AAAa:18AAaa:8Aaaa:1aaaa.  3. Tetraploid sorghum often has poor seed set.  
I don't know if, or when, diploid perennial lines will be available.

[walt]

Today I planted some tetraploid sorghum for crossing with Johnsongrass, and some ms8 sorghum for crossing with Johnsongrass and with other sorghum varieties to increase the genetic diversity in my population.
The ms8 gene is a newly found male-sterile gene that prevents formation of anthers.   This gives a male sterile plant a distinct look so it can be identified from a meter away.  Much better than the genes that make normal-appearing anthers not function.
A different gene called antherless used to be routinely used by sorghum breeders, but it was found to have undesired side effects in many breeding populations.
Using pollen from tetraploid Johnsongrass on male-sterile diploid sorghum gives very few seeds, but a good percent of such seeds are fertile tetraploids.  The rest are sterile, or nearly sterile, triploids.  Just destroy the sterile plants and you have your fertile tetraploids, or nothing.  It doesn't always work.  Dr Stan Cox says he averages maybe a seed per head.  But it is easy to pollinate many heads this way, so I'm good with this.

[walt]

Dr. Cox has discovered that some of his perennial sorghum has reverted to diploid, and remained perennial.
Some history.  domestic sorghum bicolor is generally a short-lived perennial in the tropics.  Growing it in a temperate region, it is killed by winter cold.  If crossed with a winter hardy S. halepense, which is tetraploid, strains of winter-hardy grain sorghum have been developed. 
But until a few years ago, no winter-hardy lines of diploid winter-hardy sorghum had been developed, in spite of some efforts to do so.  There were 3 reasons to prefer diploids.  1. Diploid sorghum has higher percent seed set, therefore higher yield.  2. bringing in new genes from domestic sorghum into the perennials is slowed by having to get it to tetraploid level .  3. Diploid genes segregate in 3:1 ratio, tetraploid genes segregate at 35:1 ratio.
So a couple of years ago, Dr. Cox noticed some of his perennial strains of domestic sorghum looked more like common domestic sorghum.  This year he checked chromosomes and discovered that these breeding lines are diploids.  Good for him.
So I've been thinking about how this could have happened.
Possibility 1.  Corn pollen can pollinate sorghum, though the resulting hybrid embryos can seldom survive even with the most high-tech embryo culture technics.  But sometimes, in grasses at least, a foreign pollen grain can stimulate a seed to develope that is not hybrid, but is haploid.  Cereal breeders have used this to create "instant inbreds" by doubling such haploids.  But a haploid from a tetraploid is a diploid.  This could have lead to Dr. Cox's perennial diploid sorghum.  
But while a possible way it happened, it is not the likely way, because Dr. Cox's sorghum breeding fields aren't near much corn growing.  But it is a way one might get the same result.
Possibility 2.  Dr. Liang, at Kansas State University, studied sorghum chromosomes for decades.  He noticed that while triploids from S. bicolor x S. halepense are highly sterile, they do sometimes set a seed.  And the seed always had only one set of chromosomes from the hybrid parent.  Triploid x diploid is diploid.  Triploid x tetraploid is triploid.
So although I don't actually know how Dr. Cox's perennial diploid sorghum came about, nor does he or anyone else, I see 2 possible ways to get to the same result.
This costed me a night's sleep.  Damn well worth it though.
Probably could have asked Dr. Cox if he had any guesses how it happened.  Likely would have gotten the same answers, with more besides.

[walt]

I've been seeing Johnson grass blooming for a week now. But my tetraploid grain sorghum I want to cross with Johnson grass hasn't been blooming. In fact my tetraploid grain sorghum is only about knee high or less, in spite of being started early inside.
So with the rain here I haven't been in the garden for 3 days. This morning I went to the garden, and 2 tetraploid grain sorghum plants have fat heads poking through their flag leaves. And the plants are still knee high or less, but vigorous and healthy looking. So in a week or less, I should be making the cross.

The male sterile#8 plants aren't showing signs of fat flag leaves yet.

[fliver]

My tetraploid sorghum is only about knee high and has been blooming for about a week. Is that height normal or is it a result of a dry spring/early summer?

[walt]

This is my first time growing it, and mine is coming through the flag leaf knee high.  So I think that is normal for it, since it is happening for both of us.
I also had a very dry spring, but I watered whenever I saw leaf rolling, which indicates drought stress.  So I think this is its normal height.
Not to worry, the Johnson grass will mask the dwarfing genes. which are recessive in S. bicolor.  So I'm sure the F1 will be tall.  The F2 will be almost all tall, but 1/36 or more should be somewhat shorter than the F1.  I say or more, because S. bicolor this short probly has 3 or 4 dwarfing genes, all recessive and additive.  One homozygous dwarfing gene might get it down to 2M., more or less.  Two homozygous dwarfing genes might get the plant down to 1 1/2 M, more or less.  Three will make it shorter still.  Knee high is likely four dwarfing genes working together, each homozygous.

My 4X S. bicolor will be blooming in a couple days, I think.  These are plants I started inside and transplanted.  So I think they would have been later if direct seeded.  Local Johnson grass has been blooming about 10 days already.  I'll be snapping the heads off J. grass, so it will bloom again later.  The S. bicolor will also bloom again later, though I won't be snapping its head off.  It has several tillers on most plants.  J. grass will continue blooming for a while, so I should get some crosses.

The male sterile 8 s. bicolor is not showing any swellings indicating heads yet.  I think they will be significantly taller and later.  We'll see.

[fliver]

I went out today and noticed some of my male sterile plants just now starting to push flower heads out. They are about 4 ft tall now.

[walt]

Jul 1, 2018 15:02:59 GMT -5 fliver said:

I went out today and noticed some of my male sterile plants just now starting to push flower heads out. They are about 4 ft tall now.

Congratulations.  How tall is it?

[walt]

I think the 4X sorghum is not only 4 dwarf, but also has 4 recessive maturity genes.

I'll give a short history of sorghum in the USA, in case anyone is interested.
When sorghum was first brought to the USA, it could be farmed only along the southern border.  But after many years, a farmer noticed a plant a single hear that was ripe earlier than the rest.  It stood out because ripe heads of sorghum are generally tan or brow, unripe heads are green.
So the farmer saved it and grew it out separately.  It bred true.  So north of the old sorghum belt, a new sorghum belt came into existence, using the earlier sorghum.
After many years, the same thing happened in the early sorghum, giving an even earlier maturing sorghum.  The sorghum belt extended even further north.
And again it happened, and the sorghum belt extended even further north.  
A fourth mutation happened.  I don't know if all 4 maturity genes are in use commercially.  There is a limit to how short a season sorghum can use and make a commercially useful crop.  But for experimental work, 4 maturity genes can give a really short generation to sorghum breeders.
The 4 maturity genes are recessive and can work together to give earlier sorghum.  Of course, without those 4 mutations, the hundreds or thousands of sorghum landraces grown for thousands of years in Africa, India, China, and elsewhere, each has its own maturity time, but these 4 genes make any of those landraces earlier.

The sorghum brought to the USA was tall, few if any were as short as 2 M.  In those days, sorghum, and all grains, were hand harvested. 
A farmer noticed a shorter plant and saved the seed.  It bred true, and it became popular because harvesters didn't have to reach as high to harvest, and the shorter plants were less likely to break or bend.  It was still over 2 M tall, but got the name of Dwarf Milo.  It had been found in a field of the Milo variety of sorghum.  And except for shorter internodes, it was just like Milo.
So later another farmer noticed a shorter plant, in a field of Dwarf Milo.  This became the variety Double Dwarf Milo.
So during all this time, the field harvester called the combine came into use.  When a third dwarf mutant was found, by this time there were sorghum breeders, the 3 dwarfing genes were bred into an old variety called Kaffir.  The resulting variety was short enough to use the combine to harvest it.  It was given the name Combine Kaffir.
A fourth dwarfing mutation was found.  It was used to replace one of the others, as one of them wasn't stable, giving plants that stuck up above the rest of the field, looking like the farmer didn't keep his seed pure.  Horrors!

So it appears that the 4X sorghum we have is 4 dwarf, and 4 maturity.  In the later generations from the hybrid with Johnson grass, we'll likely want 2 or 3 maturity genes, and 2 or 3 dwarfing genes.  They will be in the mix.  They just have to be sorted out.