Batatas x pandurata attempt

[Chance]

The is my first year growing out sweet potatoes from seed, maybe 25 or so plants.  One of these plants I potted and placed at another property that has a wild I. pandurata.  This lone sweet potato is forming plenty of seed.  It could be self compatible.  But the seed coat on those seeds is also unusual, mottled brown with slightly larger seeds.  I'm not growing enough numbers of different seedlings to say if it's really that unusual, but the seeds from my patch are basically all black, a few on the brown side but nothing like the lone plant's seed.  Here's a photo of some of the seed with the two mottled brown ones very distinct.  I remember Reed did this experiment and wonder if he observed something similar.

[reed]

Interesting, I've never seen seeds that look quite like that. Generally, they look like batatas, basically shaped right for it but the colors are a bit off. The extra puckers, a batatas seed just has the one, look like the embryo might not be completely formed. All I have ever seen have the classic shape but are always a single solid color. Most are just black but lighter colors show up sometimes. I've never seen one as light colored as those in the middle. Pandurata seed have the same basic shape but are larger and have a little beard of fuzz around the edge.

I attempted that cross two or three times and "I think" might have been successful. I think, because I only got about five or six seeds all together. They all looked like healthy batatas, but none sprouted and without that there was no confirmation of the cross. 

I also successfully grafted the two species just to see if I could but did not go ahead and grow them out to flowering. I think the cross might be possible, but I was still discovering how genetically weird batatas is, not to mention the weird mutation that goes on with them and decided to wait till I have a better handle on that before moving on to seriously trying it again.

I suspect, based on how batatas acts on its own it might take decades to select something out of a batatas x pandurata cross. That is assuming my same goal of a seed grown annual is applied. If we forget that then a new extremely interesting clone might show up much sooner. I may try this again next year. 


 

[Chance]

Thanks for your input Reed.  I was inspired to try this experiment after you saying you got seed before.  Some of the seeds are definitely undeveloped but the 2 brown speckled seeds in that photo are the ones grown nearby pandurata pollen.  It's interesting that you haven't seen that seed coat before.  I decided to germinate them immediately in case they contain fragile hybrid embryos, and so far there are 3 seedlings.  There don't appear to be any new seeds forming on the solo batatas now that pandurata has stopped flowering. They might not be hybrids though because the pandurata pollen could have triggered selfing.


Another seed from that plant:

[Chance]

Update: so far there are 5 seedlings growing.  4 of them had very tenacious seed coats which didn't want to easily shed from the cotyledon leaves.  Two of them look malformed with crinkled leaves, another seedling looks like a low chlorophyll mutant.  The other 2 look somewhat normal except one with irregular lobes. 

I wish I had some other sweet potato seeds growing now to compare.  My initial impression is that these have less vigor than normal sweet potato seedlings, more irregular growth, as well as being smaller.  Since I've only grown sweet potato seedlings a couple times however I'm not totally confident in this. 

If they are distant hybrids there should be enough general weirdness that continues to reveal itself.

[reed]

They look like normal batatas seedlings at this point, although they seem to be in a bit of distress. Can't guess from a photo but maybe a little too damp. Trouble shedding the seed coat is common, I mostly cured it by planting a little deeper, so it gets dragged off as the sprout emerges. Lacking chlorophyl happens, I say somewhere less than one percent of the time. I call them vampires, and they will grow slowly or rather not die, unless touched by just a bit of direct sunlight.

You're growing these now in October, in the Blueridge Mountains? 

[Chance]

I agree there is a stress condition, visible by a general crinklyness to the cotyledon leaves and shared by basically all of them.   I don't think it's growing conditions because I've grown sweet potato seedlings and currently grown other plants under the same conditions.  My impression is it's more of an intrinsic condition.  I am growing now in the blue ridge, heat mat etc., reason being that distant hybrid embryos don't necessarily survive drying. 


It will be interesting to see. All together there is stressed phenotype, weird seed coat, the mother plant stopped setting seed right when the pandurata next to it stopped flowering.  Whereas in my batatas patch of like 20 some seedlings they all set way more seed in exactly this time frame.  This seems to suggest a couple possibilities. To me it would either mean the seed are true hybrid embryos or foreign pollen induced selfing with genome shock. 

[Chance]

Reed, have you ever seen polyembryonic sweet potato seedlings?  The newest seed apparently had two embryos in it, both with slightly different colors.

[Chance]

The two embryos were grafted together in the seed at the cotyledon, making a tri cotyledon at the top (2 from the red stem and one from the white)

[reed]

I didn't know that is what it's called but I've seen similar looking things. I've seen the cotyledons fused in sort of a rosette around the stem. I've seen as many as seven distinct cotyledons, more than one tier of cotyledons, and the weirdest of all is when another stem with cotyledons ruptures the skin and splits out of the first stem. Bifurcated stems are not terribly uncommon. Most all of these things end up with poorly growing plants and some just die later on.

One time a stem instead of just bifurcated, had several stems fused together, that plant did live and grew robustly. It ended up with a flat stem about a 1/4-inch thick and over an inch wide.  When it bloomed lots of the flowers were also fused together in groups of two or more, clusters of flowers grew in straight lines along the stems, I mean a lot of them, and it made a lot of seeds.  It made twisted up storage roots completely covered in little feeder roots, and it tasted awful.

Come to think of it that one came up during the years I had pandurata growing at the edge of the garden. I don't know if that means anything, but sweet potatoes do weird things and that was extra weird. I got rid of pandurata because it was getting too big and attracted a little gold colored beetle that then found their wat to my other plants. When I dug it up it had roots about the size of my little finger, going straight down. If it had big storage roots they were far too deep for my tastes, but it must have because it kept coming back up for two or three years.

 

[Chance]

Here are two seedlings with the dominant phenotype.  This phenotype wasn't present in the previous generation seedlings but now it predominates.  The seedling parent has only light purple leaf margins.

[Chance]

A funny leaf shape emerging in a new seedling

[Chance]

Current state.   Up close photos of the underside of the leaves show vein traits that indicate some divergence from batatas.

[UnicornEmily]

This is seriously cool.  I've been curious for ages about what a cross between the two species might be like!