Colourful runner beans and interspecific crosses

[triffid]

Posted originally on the OSSI plant breeding forum if anyone wants to follow it there too:

"Runner beans, Phaseolus coccineus, are a garden and allotment staple of the British summer. They thrive in the cool and wet weather of the Isles, and struggle to set fruit properly in hot and dry spells.
However, with climate change, that characteristic cool and wet is not necessarily guaranteed anymore.
Runner beans are also boringly green.

Tozer Seeds has bred a number of runner beans with ‘French bean genetics’ that set in hotter, dryer weather and self-pollinate without insect aid.
These are boringly green too, and I’d like to change that.

‘Aeron Purple Star’ is a purple-podded runner bean discovered by (and available from) Aeron Vale Allotments Trust Chairman, Gwilym ab Ioan, in a crop of ‘Polestar’.
It has since grown true and is said to be extremely vigorous, stringless, and superior to ‘Polestar’ in flavour and tenderness.
Whether this variety is the result of a mutation or cross is unknown.

I suspect it is a mutation for the following reasons. There are extremely few purple-podded runner bean varieties with which this variety could have inherited its genetics.
I only know of three sorts; ‘Black Pod’ and ‘Chapman’s Purple’, kept by the Heritage Seed Library, and one which translates to ‘Blue Pod’, available from a Danish grower.
I’m also doubtful that ‘APS’ is the result of an intrageneric cross with P. vulgaris. Perhaps not impossible, but I have read that without embryo rescue it is unlikely to develop viable offspring with P. vulgaris as the pollen parent.

However, as one of Tozer’s newly bred self-setting runner beans, the ‘APS’ progenitor ‘Polestar’ may have P. vulgaris genetics, and if so it may be more receptive to P. vulgaris pollen.
‘APS’ could in fact be the result of a cross with a purple-podded French bean, nullifying my previous reasoning.

So, there are a lot of unknowns and suppositions, but this year I will attempt to make a start on unraveling some of these mysteries:

• I am hoping to find out if anthocyanin expression in the pod is dominant, co-dominant or incompletely dominant by crossing ‘APS’ with green runner beans. There's a variety called 'Yardstick' that has purple striping.
• I will attempt to test whether the P. coccineus x P. vulgaris varieties bred by Tozer set viable seed when subsequently pollinated by P. vulgaris. There are many of these runners available in the UK - this year I will be making crosses with ‘Moonlight’, ‘Firestorm’, ‘White Lady’, and ‘Wey’, but also on the market are ‘Aurora’, ‘Celebration’, ‘Firelight’, ‘Saint George’, ‘Snowstorm’, ‘Stardust’, ‘Sunset’, ‘Tenderstar’ and ‘Snowdrift’.
• Veitch’s Wonder’ is a vulgaris x coccineus dwarf green bean of J. Veitch & Sons, 1910, that I will be using in some experiments as a ‘bridge’ between the two species. The seeds of this variety bear striking resemblance to runner beans.

I’ll be making crosses to the Tozer runners with yellow, red and purple-podded French beans. Also crossing the Tozer runners with common runner beans to see if the F1 progeny is receptive to vulgaris pollen.

There are experts and professionals on this forum who have the knowledge to correct my mistakes and point me in the right direction regarding this project, perhaps even to make most of the experiments unnecessary.
What is unknown to me is likely common knowledge in literature, but I haven’t yet found the studies. Any advice and comments, as always, are greatly appreciated."

[triffid]

A note on 'Veitch's Wonder' aka 'Nain de Veitch' - I obtained seed from Guy Dirix (belleepoquemeise.be). It is claimed to have been rediscovered in a Colombian genebank by the seed hunter Lieven Decrick, in 2015.

[Galina]

Triffid, these are very interesting plans. Addressing the question whether these self setting runner beans really are crosses and breeding more colours into pods if the cross can be done with French bean pollen and runner bean mother. I think I may have already mentioned that I got very different setting rates when bagging runner bean flowers without hand pollination, just by shaking the baggies. Painted Lady for one did self set quite well, others not much.

Just a few comments about the Aeron Purple Star runner bean. I asked for a sample when they were first available and grew them. There were some which had purple pods, others green, some with long pods others shorter and some with partially purple pods. I believe a lot of selection has been done since then to get a properly purple new variety. Long story short, had it been a mutation to purple, I would have expected uniformity rather than what I saw in the first generation that was shared. Secondly have you contacted Gwilym Ab Ioan, the breeder? His own gardening group has closed due to illness, but he is on facebook and can hopefully be reached to answer your questions. You may be aware of the breeder's posts on A4A https://www.allotments4all.co.uk/smf...wposts;u=52363

A very interesting project and I wish you all the best of luck with it.

[triffid]

Thank you Galina. So APS was segregating early on.. interesting.. yes I would have to agree with you that based on this observation I would also presume it's a cross rather than mutation. So it's a question of where did the purple come from? I've haven't contacted Gwilym yet, aside from my initial request for a few seeds. Do you still grow APS?

[Galina]

Just found Polestar in a 1996 Marshall's catalogue. (Love old catalogues and have kept far too many). They say it is stringless and sets very easily. None of the runner beans with French bean genes in them existed or were offered by Marshall's at that time.

[triffid]

Great detective work!

[Jang]

Yes, great research! But I’m struggling to follow the implications of your comment.
Are you concluding that stringlessness and ease of setting are features which have been selected for within coccineus and that the claims of vulgaris genes in other such varieties are thrown still more into doubt?

Is it that your experience would suggest that there were no naturally occurring crosses with stable predominantly coccineus features? But Is it possible that whatever Tozers has been doing more recently was being done previously but seed companies didn’t bother to present it as a selling feature?

Please could you just spell it out for me. 🙏🙏

[Jang]

I've asked for a few APS seeds too. I got interested in it a couple of years ago but didn't quite get to it. It will be interesting to compare notes on how stable it turns out to be. As you say, if it's purple, stringless and long podded it will be to be treasured. And great perhaps for some breeding explorations.

I've never grown Polestar so haven't experienced the stringlessness. A friend has given me a few seeds of Galaxy which also claims to be stringless. However both of these fit into the boringly green category, of course! But interesting that you think stringlessness might have been introduced by the introduction of Ph vulgaris genes

I also received Nain de Veitch this year but from Bohnen-Atlas so I'm very interested in your plans to use it in further interspecific crossing. I hope it goes very well; the results could be very illuminating.

"I’m also doubtful that ‘APS’ is the result of an intrageneric cross with P. vulgaris. Perhaps not impossible, but I have read that without embryo rescue it is unlikely to develop viable offspring with P. vulgaris as the pollen parent". Does this mean that in any crossing you do you will need to take the pollen from the Ph coccineus and make the Ph vulgaris the mother plant?

[triffid]

I don't necessarily think that stringlessness is a quality introduced by vulgaris genes, though it may well be the case. I'm more focussed on the ability to self-pollinate as the result of vulgaris genes. Tozer themselves declare a number of varieties have this trait as a result of their interspecies breeding. If you look through RHS AGM trail records they also mention certain varieties have incorporated vulgaris genetics.
Yes, if one was to cross a regular runner bean with a French bean, one would expect some success with vulgaris as the mother plant. I believe galina has had some fortuitous natural crosses occur. I don't know why it doesn't seem to work the other way around. But I would like to try with the 'French bean genetics' runners, in case what changed to make them self-pollinating also will make them receptive to vulgaris pollen. But as galina said, some regular runners are quiet adept at self-pollinating.

[Jang]

I’m several steps behind here with much more enthusiasm than experience but have been looking for further information on these supposedly crossed varieties coming from the Tozer stable.

I know, Galina, that you have expressed quite strong doubts about whether they are in fact bona fide crosses, on the grounds, I think, that crosses in your experience have been unstable and soon reverted to more of a vulgaris type in successive generations (correct me if I’m not accurately representing your reservations)

I haven’t been able to find any direct reference from Tozer themselves to be basing their newer strains of runner beans on crossing with vulgaris. Perhaps references have lapsed or perhaps I’m just not finding them. There is a third party assertion here: https://www.innovationfarm.co.uk/pag...-proteins-2012
but I don’t know how authoritative it is.

I imagine the RHS trial report of 2013 should be authoritative and it seems that all the new varieties presented that year for assessment for AGMs ( http://apps.rhs.org.uk/planttrials/TrialReports/Bean%20runner%202013.pdf ) were claimed to be crosses: Moonlight, Snowstorm, Stardust, Firestorm, Flavourstar. (Tenderstar and White Emergo don’t seem to have been presented for assessment and I don’t know where Polestar fits in. Three earlier varieties already with AGMs were claimed to have ‘some French bean parentage)

Deppe perhaps led the way with the idea that companies feign hybridisation in order to deter seed-saving and I suppose RHS can only pass on the information they’re given. But if such fudging/dishonesty exists in such high places that is extremely dispiriting.

[Galina]

Yes I have expressed doubt based on experience that for example Painted Lady self sets quite well and others like Butler for example does not. Also Tozer and others have never spelled out clearly whether they crossed their new runner beans or by which other means they arrived at a 'has French Bean genes in it'. Gene editing or splicing between different species of bean, rather than traditional crossing. My naturally occurring crosses have been runner to French bean and most of the runner bean characteristics got lost the further down the generations I followed up. Different from French beans in early generations especially in flower colour and more robust plants, but later on much more French bean like, with the exception of showing no inclination to becoming a stable variety. I would like to know much more about the process by which French bean genes have been inserted into a runner bean to believe it. Interesting reading Jang. I studied the photos in the RHS reference. The fleshier, rounder pods of the interspecies hybrid varieties look the same to me as the traditional thing. And there is no mention that these are hybrids, so presumably they must be true breeding.

Have finally bought seeds for one of them. Will be interesting growing them and saving seeds from them. I found and have heard from others that purple podded varieties are more prone to cross with runner beans. So one experiment could be grow a purple podded French bean with one of these new runners on the same wigwam away from others, and then grow out seeds from both and hope for a natural cross. Hand pollination should be better, if I can teach myself how to do it reliably, similar to peas but the flower anatomy makes it more difficult. Should I get a cross both ways that would convince me that they are indeed interspecies hybrids after all. Maybe not an experiment for this year, but something to consider.

It is easy to recognise a cross with runner in a French bean, because there are no French beans with red or red and white flowers. I wonder how you recognise a French bean cross in a Runner bean should it have worked that way round too.

[Jang]

I’ve reread your detailed initial reply here Galina. Lots in it to think about.
You mention gene editing and splicing. Presumably gene editing is done in a lab, but splicing would be a grafting technique of some kind?
This raised questions in my mind as to how genes might be shared between two plants used in a splice. I’m only really familiar with apple tree grafting where as far as I know it’s just the dwarfing of the rootstock which is passed on. Are there examples of a more general sharing of characteristics I wonder.

[Galina]

Without knowing anything about the process, the terms splicing and editing I have used for the process of taking some genes and replacing with some others. Being mindful that I do not know whether this is what Tozers are doing, and that it could equally be traditional breeding by crossing. The fact that they do not spell out how these French bean genes got into their runner beans makes me wonder whether they have done breeding with any preexisting interspecies crosses. Or whether and by which methods they themselves added French bean genes into their runners.

[Jang]

Ah well, the mystery and obfuscation remain. I don't suppose it's even worth sending them an enquiry. They clearly don't want to share their insights and techniques.

[Galina]

Deppe perhaps led the way with the idea that companies feign hybridisation in order to deter seed-saving and I suppose RHS can only pass on the information they’re given. But if such fudging/dishonesty exists in such high places that is extremely dispiriting.

One of the European seed rules is that information about whether a plant is a hybrid or not should be clearly displayed on a seed packet. I agree that on occasion it is not.

Still begs the question. What is this Tozer bred runner bean which has 'French bean genes in it' and how did they get there. Do other traditional runner beans also have these genes in them and Tozer made use of it by breeding with those varieties or did they do their own interspecies work and if so, by what means?

[triffid]

Saw in an Unwins catalogue sent to me, a pea named 'Snow Wind' F1. Somehow I don't believe them.

[Galina]

I don't either, but with their hypertendrils, some folk would believe that this is a hybrid, because they look different. Googling them, most seed companies who sell them do not label them as F1. It is clearly wrong.

[jayb]

Taste. Probably nothing to do with it but

I adore runner beans and I love their taste better than french beans. I can't think of a single french bean variety which would knock spots of a runner but plenty of runner varieties which ace the Frenchies. However, the modern wave of "self setting" (possibly with french gene in) varieties I find that they generally taste inferior to other runner varieties. I've now grown several different varieties of the "new" runners, they just don't have the same wow factor. Though I do like Red Rum perhaps influenced as they make a good early and then late variety for the polytunnel.

[Jang]

Interesting. I’ve found Red Rum very acceptable - and useful - in the past too.
I’ll be growing a couple more of the ‘self-setters’ this year. I shall subject them to more careful taste scrutiny.

[Jang]

A further thought about the ‘self-setting’, apparently stringless beans which are being fairly widely marketed.
The two I have are Galaxy and Firestorm, and although I can’t find an explicit reference to Galaxy having either been bred by Tozers or being claimed to definitely have some French bean parentage , I’m assuming it’s been created in the same way.
But my observation is how similar the seeds are and that they’re unlike any other runner bean seed I’ve met (not a huge range). I wonder whether all the beans of this type look similar and whether the appearance of the seeds might say anything about their parentage.

[Galina]

Prizewinner and from HSL Lord Mildmay's have the same pattern. This is a traditional runnerbean seed coat pattern.

Still the question what do all the different seedcoat patterns signify, is a very valid one and interesting. Does anybody know?

[Jang]

Ah thanks. Interesting but not in the way I was was wondering about.

Opens up a much wider question but difficult to know how to pursue it....... ?

[jayb]

I'm not sure what the differences mean, though to me the two examples above are similar they are not the same. Perhaps they could be subdivided further. I know I have with what I think are similar patterns, I'll check them out and see if I can get a couple of pictures.

[triffid]

I've come across a study from 1995 regarding the breeding of dwarf runner beans. It lays out how they crossed various dwarf French beans with 'Bianco di Spagna', a type of dry shelling runner bean, in order to achieve determinate runner beans suitable for mechanical harvesting. It's all achieved with conventional breeding - vulgaris x coccineus F1, then three backcrosses with P. coccineus as the male parent, and finally a backcross with P. coccineus as the female parent to change the cytoplasm. This resulted in plants with the phenotypic characteristics of a runner bean, including hypogeal germination, but with a dwarf habit. https://doi.org/10.21273/HORTSCI.30.7.1483
This is along the lines of why I had suspected Veitch's Wonder, as a vulgaris x coccineus, might be useful as a mediator between the two species.

There are quite a few dwarf runner beans on the market and if this is how they were all bred, then there are many 'French bean genetics' varieties out there that are not even marketed as such. If it's so commonplace, and has been a commercial breeding practice from at least the 80s (http://www.hortorumcultus.actapol.net/pub/9_3_117.pdf), I have much less reason to doubt that the Tozer varieties are hybrids. Who knows, one could speculate the tall hybrid runners were an unintended product of the determinate runner bean projects with their own marketable merits.

[Galina]

I am happy that you are getting to the bottom of these interspecies crosses triffid. Proves me wrong, but that is fine in the face of proper evidence to the contrary. Thank you.

[triffid]

Doesn't unequivocally prove you wrong. I still don't have a source to substantiate the claims that Tozer's varieties are truly hybrids, apart from their own marketing. But my personal reasoning leads me to believe that they had no reason to fabricate the claim, if the literature shows professional plant breeders have been doing it for decades.

[Galina]

That makes very good sense Triffid

[Galina]

A complete aside. The plastic bag containing last year's runnerbean roots has sprung into life, got watered and is now placed next to a window. The first shoot has sprung up from the overwintered roots. Considering I really have not paid any attention to this bag and certainly not watered, this is such a welcome harbinger of spring and of new life.

[Galina]

No, I am used to mid May as the last frost date. But we had several occasions of an early June frost and associated losses. Had one bean that I grew for the first time where half the plants perished. The next time I grew the variety (this time from my own seeds) by chance we also happened to have a very late frost year and not a single plant of that variety perished. The power of selection.

[Jang]

That sounds tough but I love your example of selection adapting to local conditions in a single generation.

Since you wrote this I’ve looked more carefully into expected last frost dates for where I live and for England and Wales generally.
I find I’m right on a border between a coastal strip which has last week of April expected frosts and the more inland area which has second week of May. So it’s a little difficult to gauge. But I’ve freshly realised that this strip, which follows the coast, is quite well favoured in that respect.

So maybe you gain a week or two extra of growing season. 🤞🤞

[Galina]

Jang, there is the last frost date and there is the more practical consideration of 'what can I protect and how can I do it, should I have to'. In the case of those beans, they were already out of their bottles and had started climbing up the poles. More difficult to protect. Stuff under bottles or for example potatoes that can be protected with a sheet of fleece are easier to do. I think wherever we garden, a remote outside thermometer is very useful. I also found, for example, that squashes that were not established and growing before the second half of June, would never catch up properly. Had I planted those out 'after all risk of frost has gone' I would have never had any success with them. Normally our first courgettes were harvested in August, by planting before the last frost date and protecting. Sorry this is now a serious thread drift, but (awkward sharp turn about ) fortunately runner beans are a little more frost hardy than French beans.