Cold tolerant tomatoes, right down Joseph's alley.

[DarJones]

Habrochaites varies as much within the species as all the variation across species. In other words, some Habrochaites lines will have good resistance, others poor.

Are you measuring the right thing? The physical structure of a tomato plant does not include antifreeze which is usually some form of sugar accumulated in the leaves. Take a tomato plant below 25 degrees and it will almost always freeze and die to the ground. Some work in Russia indicates epigenetics play a large part in tomato cold resistance. There are reports of plants thriving after overnight temps as low as 17F.

I think it would be better to focus effort on the area where tomatoes need the most help. 32°F to 50°F is the range where normal tomato plants show severe cold stress. Leaves shrivel, turn yellow, wilt, stems lose turgor, roots stop absorbing water. Rubisco is deactivated by free radicals with byproducts accumulating which causes the leaves to die. If you want to change the paradigm with tomato, breed for the ability to thrive at 35°F. This would require growing lots of seedlings under standardized conditions and exposing them to low temps for gradually increasing intervals. Earlinorth has the ft gene which triggers fruit set at 40°F. Combining ft with genes in LA3969 plus genes for stress tolerance should be possible in a few years.

[mjc]

May 24, 2017 14:19:47 GMT -5 William said:

Could Epigenetics explain this or is it the physics of ground level temp?

My guess is that physics would be the major player here...

[keen101 (Biolumo / Andrew B.)]

I suspect any varieties with the atv and Aft or other anthocyanin genes will have a greater degree of cold stress tolerance as that is the trend observed with many of my varieties such as indian corn (maize). The anthocyanins are able to function at colder temperatures than chlorophyll so they can still convert some sunlight to sugars but they may also act as a sort of antifreeze of sorts.

Solanum lycopersicoides, S. chilense, S. peruvianum may have the best chance in this regard.

LA1996 is one of the ones i'm growing this year. It has lots of anthocyanin in the leaves and was one of many that survived our late frost with no sign of annoyance. Interestingly i didn't know until now that LA1996 is a S. chilense hybrid. tgrc.ucdavis.edu/data/acc/AccDetail.aspx?AccessionNum=LA1996. I believe the S. pennellii hybrid also shows anthocyanins in the leaves.

[DarJones]

Anything that helps prevent frost forming on the leaves will increase survival of tomatoes. When frost forms, the ice crystals trigger crystal formation inside the leaves which then kills them. This is a different paradigm than that presented at temps between 32F and 50F where most tomato plants undergo rubisco deactivation. Some work done years ago showed that bacteria on the leaf surface are the primary trigger for frost crystals to form. Spraying the plants with competing bacteria that do not act as nuclei for crystal growth protects the plants from frost killing.

[keen101 (Biolumo / Andrew B.)]

Interesting... So if we take that info and run with it a bit then that means that theoretically by breeding with wild tomatoes that have different chemicals and biochemistry that it could be possible to breed a tomato plant that has a different chemical makeup and therefore would be a host to a different range of bacteria. And by continually selecting for those plants that survive frost and ice we unknowingly could be selecting for bacteria that do not help form ice crystals...

[walt]

Or just had different kinds of bacteria on it.
Not expressing an opinion, just pointing out another possablity.

[philagardener]

Legumes have a huge advantage from their ability to form root nodules that host nitrogen-fixing bacteria.

Leaf surfaces that suppress ice crystal formation (whatever the mechanism) or herbivory (via hosting Bt types of bacteria or just having lots of hairy trichomes) could be quite valuable.

[keen101 (Biolumo / Andrew B.)]

Jun 1, 2017 5:37:34 GMT -5 philagardener said:

Leaf surfaces that suppress ice crystal formation (whatever the mechanism) or herbivory (via hosting Bt types of bacteria or just having lots of hairy trichomes) could be quite valuable.

Speaking of interesting leaf surfaces and perhaps haivng lots of hairy trichomes.. i noticed today a few plants that looked to have silvery leaves. When i inspected closer it may have just been water condensation on top of lots of little hairs. But the silvery looking tomatoes were best to least: LA4135 the F1 S. pennellii hybrid, S. Peruvianum, and one of the S. galapagense lines. Since Solanum pennellii is supposed to have waxy leaves that help in dry desert climates this is not surprising and is actually exciting. I also have one small S. pennellii seedling in a pot. Hope it survives so i can try doing a one-direction backcross LA4135 x S. pennellii.

S. chilense and S. pennelli are indigenous to arid and semi-arid environments of South America. Both species produce small green fruit and have an indeterminate growth habit.S chilenseis adapted to desert areas of northernChile and often found in areas where no other vegetation grows (Maldonadoet al.2003), has finely divided leaves and well-developed root system andhas a longer primary root andmore extensive secondary root system than cultivated tomato(O’Connellet al.2007).•Drought tests show that S. chilenseis five times more tolerant of wilting than cultivated tomato.S.pennellii has the ability to increase its water use efficiency under drought conditions unlike the cultivated S. lycopersicum (O’Connelletal.2007). It has thick, round waxy leaves, is known to produce acyl-sugars in its trichomes, and its leaves are able to take updew (Rick 1973).

Source: www.pphouse.org/admin/uploadpdf/IJEP%204.pdf

[Joseph Lofthouse]

Here's what one of my Solanum chilense plants looked like a few minutes ago. Those are rather silvery leaves!

[walt]

Jun 8, 2017 12:52:44 GMT -5 keen101 (Biolumo / Andrew B.) said:

Jun 1, 2017 5:37:34 GMT -5 philagardener said:

Speaking of interesting leaf surfaces and perhaps haivng lots of hairy trichomes.. i noticed today a few plants that looked to have silvery leaves. When i inspected closer it may have just been water condensation on top of lots of little hairs. But the silvery looking tomatoes were best to least: LA4135 the F1 S. pennellii hybrid, S. Peruvianum, and one of the S. galapagense lines. Since Solanum pennellii is supposed to have waxy leaves that help in dry desert climates this is not surprising and is actually exciting. I also have one small S. pennellii seedling in a pot. Hope it survives so i can try doing a one-direction backcross LA4135 x S. pennellii.

S. chilense and S. pennelli are indigenous to arid and semi-arid environments of South America. Both species produce small green fruit and have an indeterminate growth habit.S chilenseis adapted to desert areas of northernChile and often found in areas where no other vegetation grows (Maldonadoet al.2003), has finely divided leaves and well-developed root system andhas a longer primary root andmore extensive secondary root system than cultivated tomato(O’Connellet al.2007).•Drought tests show that S. chilenseis five times more tolerant of wilting than cultivated tomato.S.pennellii has the ability to increase its water use efficiency under drought conditions unlike the cultivated S. lycopersicum (O’Connelletal.2007). It has thick, round waxy leaves, is known to produce acyl-sugars in its trichomes, and its leaves are able to take updew (Rick 1973).

Source: www.pphouse.org/admin/uploadpdf/IJEP%204.pdf

I have read, I think in the newsletter of the tomato genetics cooperative, that S. pennelli is fron the coastal desert where it almost never rains, but fog comes in from the ocean almost every night.  So the roots are actually not exceptional at soaking up rain water, as one might ordinarily think of being arid-adapted.  The article said that because of this, its F1 and some F2 segregants with S. lycopersicum are more drought tolerant than S. pennelli.

[Joseph Lofthouse]

Jun 8, 2017 18:33:36 GMT -5 walt said:

I have read, I think in the newsletter of the tomato genetics cooperative, that S. pennelli is fron the coastal desert where it almost never rains, but fog comes in from the ocean almost every night.

Thanks Walt! Last time I grew Solanum pennellii, it did extremely poorly for me. Relative humidity here yesterday afternoon was 6%. I don't expect any dew until September. I transplanted some plants the other day. The roots were delicate and weak. They broke off extremely easily. Nevertheless, even with most of the roots gone, the plants are not wilting in the heat. This suggests a strategy of how to grow Solanum pennellii at my place: Give it a misting of water each evening...

[keen101 (Biolumo / Andrew B.)]

Yes, you might be on to something with that! I read in a paper that S. pennellii soaks water through pores in the leaves and that during the day they close up to conserve it.

In addition the S. Chilense are supposed to have one of the largest roots in the tomato family and are excellent at drought tolerance from a root perspective, which is why they are a good hybrid rootstock i guess.

A good drought tolerant cross might be to take the best from each of these families.

S. chilense and S. pennelli are
indigenous to arid and semi-arid environments of South America. Both species
produce small green fruit and have an indeterminate growth habit. S chilense is
adapted to desert areas of northern Chile and often found in areas where no other
vegetation grows. S. chilense has finely divided leaves and well-developed root
system. S. chilense has a longer primary root and more extensive secondary root
system than cultivated tomato. Drought tests show that S. chilense is five times more
tolerant of wilting than cultivated tomato. S. pennellii has the ability to increase its
water use efficiency under drought conditions unlike the cultivated S. lycopersicum
(O'Connell et al. 2007). It has thick, round waxy leaves, is known to produce acylsugars
in its trichomes, and its leaves are able to take up dew. Transfer and utilization
of genes from these drought resistant species will enhance tolerance of tomato
cultivars to dry conditions, although wide crosses with S. pennellii produce fertile
progenies, S. chilense is cross-incompatible with S. lycopersicum and embryo rescue
through tissue culture is required to produce progeny plants. Research at AVRDC
and other institutions is in progress to identify the genetic factors underlying drought
tolerance in S. chilense and S. pennellii, and to transfer these factors into cultivated

www.yspuniversity.ac.in/vgc/caft/Vegetable%20Production%20under%20changing%20climate%20scenerio.PDF

[walt]

Thanks for the link.

In  1979 I was breeding and multiplying seed for export I'm Niger.  It was just south of the Sahara and humidity was around 4% in the dry season.  So of course I tried crossing S.pennellii with S. lycopersicum.
Of the packet of seeds I got only one plant to maturity.  It set one fruit on S. lycopersicum.  The fruit had 3  seeds that looked good.  Only one germinated.  It died in a week or less.
I don't say this to discourage people.  There is much more information available now.  I hope to see people succeed.

And the solution to getting tomatoes and peppers into Nigeriens' diet had a simpler solution.  Almost all Nigeriens bathed daily with a bucket of water each.  This was done outside, with a woven grass mat hung for privacy.  A couple of tomato plants and a couple of hot pepper plants by the bath area was a better solution than breeding drought tolerant tomatoes.

[steev]

So often the solution to our problem is right under our butts, if we can just pull our heads out.

[Earl]

Over 100 determinate varieties here myself...the "high-tunnel"/hoophouse has sent my growth rates OFF the chart! so far so good...Cold Set and Buckbee's New Fifty Day have blossoms ON.....SWEET!