Monday, 24 May 2010

Oh Heck, Here's Mecha-meck

In my quest to create the perfect sweetpotato for our unsympathetic climate, I've been doing a bit of hunting around for some of its wild relatives. This is an approach used by proper plant breeders to introduce genes for disease resistance and adaptability into major crops. I'm not sure whether this means that I'm now dragging myself up to their level, or whether the plant breeding brethren (and sistren) will be tainted by association with my madcap antics. If you don't tell, I won't either.

Mecha-meck or bigroot morning glory (Ipomoea pandurata) is one of the most cold tolerant sweetpotato relatives, being found in parts of the Eastern USA and Canada which have much colder winters than we do here in the UK. Its roots are edible and taste, unsurprisingly, like a sweetpotato, although several references mention that they are often somewhat bitter. Although said roots can survive sub-zero temperatures with ease, it doesn't mean that the vines that issue from them are going to like our cloudy, cool summers. It's what I call the Maypop Paradox, after the "hardy" passionflower Passiflora incarnata. It comes from the same neck of the woods as mecha-meck and although it can easily survive our laughably mild winters in a dormant state, our summers (or lack thereof) are fatal to it. At least whenever I try and grow it. I'm reminded of Mark Twain's supposed quip about the coldest winter he ever spent being a summer in San Francisco. He should have visited Cornwall. Anyway, my guess is that mecha-meck is cast in the same mould and at best its vigour will be severely checked by that lack of summer warmth. Time will tell.

It does, however, have a close relative, Ipomoea leptophylla, which grows out in the western USA at quite high altitudes, up to 2000 metres or so in Colorado, for instance. It has been described variously as delicious, or as a famine food - take your pick. One of I. leptophylla's vernacular names is "manroot" - I suggest caution when Googling that name and make no claims expressed or implied as to what sort of images or text may storm your computer as a result.

Rather than a vine, I. leptophylla is distinctly bushy, which might make it easier to manage as a garden plant. It might take cooler summer temperatures in its stride. That set me thinking about how it might be fun to have a go at crossing the two species and seeing what comes out. That's a lot of mights for one paragraph, but three mights don't make me wrong do they?

These are the seeds of mecha-meck, looking like shaggy understudies for Cousin Itt from The Addams Family. I'm not sure what the purpose of the coiffure is - the seeds are about 1cm long - quite substantial - and I can't imagine that even this amount of fluff would carry them very far on the breeze.

Here are some mecha-meck seedlings with the distinctive delta wing cotyledons which all the Ipomoea species I've ever grown seem to display.

Sweetpotato is a hexaploid with six sets of each chromosome (2n = 6x = 90) whereas mecha-meck and manroot are both diploid (2n = 30); most of the literature suggests that interspecies crosses between sweetpotato and its wild relatives are hard to achieve anyway - never mind the differences in ploidy - which isn't really what I wanted to hear. However, last year's impossibility is this year's commonplace: I recently came across a paper by some Chinese researchers where they had managed to do exactly this. The abstract is here. The actual paper lurks behind a paywall, thumbing its nose, no doubt, at us mere mortals who don't fancy spending $34 on the full text.

This idea of using I. pandurata to increase the cold hardiness of sweetpotato is nothing new - I'm merely ram-raiding the vaults of yesteryear and grabbing whatever takes my fancy. In a 1935 paper in the Journal of Heredity, M G Tioutine outlines his work on breeding sweetpotatoes in the USSR and goes on to describe his attempts at crossing I. batatas with I. pandurata. A few pods were formed, but there's no mention of whether they contained viable seeds or not. I haven't found any other papers referring to his further research on this front either. Judging by the fate of Vavilov, working as a plant breeder and geneticist at this time was not, perhaps, the safest career path in Soviet science. (There's more on Vavilov at Vaviblog - a great, great man).

Tovarishch Tioutine does, however, describe the roots of I. pandurata as tasting similar to Jerusalem artichokes, which doesn't sound so bad after all. Perhaps it's just a case of harvesting them young, before they become tainted with whatever it is that makes them bitter.

So all I need to do now is get hold of some I. leptophylla seeds, grow the plants to maturity, then set up an Ipomoea menage a trois with I. pandurata and the best adapted I. batatas varieties, including ones from the highest sweepotato plots in the Highlands of Papua New Guinea.

Should be an absolute breeze. In the meantime, I'm waiting on the universe to deliver me seeds of yet another Ipomoea: the fabled sweet-tasting, high altitude Andean species I. minuta. I'll throw that into the mix when it finally arrives. I don't know what the collective noun for a disparate bunch of ipomoeas is - could it be an entanglement? What I do know is that I'd like the chromosomes of this motley crew of morning glories to commingle and maybe create something interesting in subsequent generations. You say potato, but I say batatas - and I won't call the whole thing off.


Vegetable Heaven said...

Makes me wish I liked sweet potato!

Mark said...

Sweet potato is delicious if roasted, although given the choice I would still go for roasted parsnips.

Owen, you should start an agricultural botanic garden devoted to tubers in your part of the world. Then we can all come and live and work there in a tuberous heaven.

Ray said...

An enjoyable read and interesting adventure.

Rhizowen said...

Hi Vegetable Heaven

Maybe you should try a variety like T65 which is drier and not as sweet as the typical orange moist fleshed ones. It's similar to the "Boniato" types found in Latin America.

Hi Mark
When I've got the logistics of that proposition sorted out, I will certainly be contacting you.

Hi Ray
Glad you enjoyed it.

Rebsie Fairholm said...

Wow, what groovy seeds. I wonder what evolutionary pressures made them feel the need to disguise themselves as angora guinea pigs?

I completely share your frustration about the paywall for research papers. I was excitedly trying to enlighten myself about potato anthocyanins the other day when I hit the $34 barrier. Maybe it's just a safety device to stop uneducated oiks like me from overloading our brains and suffering an inferiority complex and low sense of self-worth when I find I don't understand a word of it.

Rhizowen said...

Hi Rebsie

It's weird as most other ipomoeas have really smooth seeds.

What was the title of the paper/ authors/ journal?

You can't be an uneducated oik with a shrivelled sense of self-worth - I bet more people have listened to and enjoyed your music than have read the paper on anthocyanins. Your descriptions of your pea breeding experiments are a model of clarity and you come from Cheltenham, which is, to my oikish mind, a superior location. You're doing fine.

Mark said...

our university subscribes to Euphytica. I have downloaded the pdf. I will forward it to you.

Rebsie Fairholm said...

Aww, thanks Owen, I appreciate your encouragement. I'm acutely aware of being an artist dabbling in a scientists' world, often paddling way out of my depth - but I suppose the strength of being untrained is having an open mind and an ability to translate things into layman's terms and open it up to others.

The paper I was trying to access was S. Eichhorn and P. Winterhalter (2005) "Anthocyanins from pigmented potato varieties" in Food Research International, and the catchily titled "Cultivar differences of total anthocyanins and anthocyanidins in red and purple-fleshed potatoes and their relation to antioxidant activity" by J. Lachman et al (2009) in Food Chemistry. There's a fair bit of useful info in the abstracts, and as I know next to nothing about biochemistry I probably won't understand most of the paper even if I could access it, but I like to better myself by struggling along with these things.

Talking of music, it'd be nice to hear your endeavours with the old 12-string.

Mark said...

we also subscribe to food chemistry, I can send the pdf doc to you (email me at . As regards the other, academics are often willing to send their copy of the document to you if you ask.

found another tuberous wonder you can grow Platycodon grandiflorus! It is called doraji in Korea. It is beautiful blue flowered plant and the root is edible.

Rhizowen said...

Hi Mark

I knew Platycodon was medicinal - good for asthma- and it also grows OK here. I'm guessing it would be a bit similar to rampion, Campanula rapunculus in flavour and texture. I seem to have an aversion to eating plants that are particularly slow growing/ornamental and from what I remember, Platycodon resents root disturbance/ division, so I would be afraid of harvesting the root and killing the crown. Maybe I should try it anyway -in the name of science. This proposed garden of tuberous delights is getting bigger by the day. Just need an army of indentured peasants to do the hard graft. Feed 'em maca powder.

Hi Rebsie

Paywallbusterman to the rescue - wonders of the internet manifested. I shouldn't worry about being out of your depth - you're reading relevant literature, carrying out experiments - that sounds like science to me. If you aren't paddling out of your depth, you're not doing it right. No-one is born with this knowledge. As Mark says, most authors are quite flattered when you contact them for copies of their papers - they then know that at least two people out of 6 billion+ have read them.

Haven't touched the 12 string since we went WWOOFing in the antipodes over a decade ago. It's
located in a quaint Cornish cottage with 100% humidity a few miles from here, so I'm expecting the strings will be as rusty, if not more so, than me. It's funny but even really simple things (that's my level) which sound a bit ordinary on a six string, take on a strange, resonant power on a twelve string. Maybe that's because I keep missing the strings I mean to play. Another characteristic of my style.

Rhizowen said...

Meant to say thanks Mark for the paper - very interesting - just apply gibberllins and cytokinins and bingo!

Rebsie Fairholm said...

Thank you Mark, that's very kind of you.

Owen ... you're right, there is a valid place for backyard science, and I shouldn't really feel inferior for being self-educated. There's a lot to be said for studying something because you're passionate about it rather than because you're obliged to. And although most academic papers seem to be over my head, it does still sink in on some level. I will probably read through the potato anthocyanins paper ten times and still be thinking "hnh?" but some time later when I'm gazing at the coloured spuds grown from my own experiments I'll go "yowwww! It all makes sense now!"

Oh the magical sound of a 12-string ... it brings a special resonance to everything. I'm not a very good guitarist, I'm really a singer who has had to learn to accompany myself out of necessity, but the 12-string makes me sound a better player than I am. When people express surprise that I always play 12-string on everything, I say it's because having two strings for each note gives me double the chance of hitting the right one. They usually think I'm joking. I'm not.

Joan Lambert Bailey said...

I thought you might find this organization - PROINPA ( interesting and helpful. The site is all in Spanish, but an heirloom vegetable enthusiast I interviewed for another blog I write for recommended it as a great source. I can send along the other links or the interview if you like. Just let me know. Thinking good sweet potato growing thoughts for you!

Rhizowen said...

Thanks Joan

I know of PROINPA - it is a useful source as you say.

Thanks for thinking good sweetpotato thoughts for me - I do believe it's working.

Ron_Convolvulaceae said...

Hello - My name is Ron (I use Ron_Convolvulaceae on the web or Ron on FB and I am very familiar with the Ipomoea species you are addressing including species identification via seed characteristics.

The seeds you have posted are those of Ipomoea macrorhiza , not Ipomoea pandurata.

I thought you might like to know.



Rhizowen said...

Hi Ron

Thanks so much for pointing this out. It appears to be case of oh, heck, it ain't mecha-meck! If you know of somewhere I can source the true Ipomoea pandurata, I'd be very grateful to know.

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