Pocket Plum query

[diggleken]

Hi all,

has anyone any idea whether Pocket Plum – Typrina pruni and T padi can be told apart in the field or in hand?

And what the difference is microscopically too?

Andy Overall pointed out on another forum, rightly, that there can be an overlap with hosts of Prunus genus, – P domestica , spinosa, padus etc and we thought someone out there may have some specific knowledge to make life easier in the field.

Cheers

Ken

[Chris Yeates]

Hi Ken

I get the overlap between Prunus spinosa and P. domestica, indeed the latter may have been bred from the former and you do get confusing intermediates (hybrids?). But both are host to Taphrina pruni.

Prunus padus should normally be easy to separate in the field; whereas P. spinosa has its flowers in ones or twos, and P. domestica generally in twos and threes, P. padus has long racemes of up to 20+ flowers/fruits and is host to Taphrina padi. One microscopical difference is that the asci of the latter are usually considerably larger than those of the former, but as the hosts are easy to distinguish: spinosa/domestica and padus there shouldn’t be any confusion.

Where it gets tricky IMO is when it comes to rusts – note what I say in the Yorkshire Rusts paper I sent you. The two Tranzschelia species one on spinosa and one on domestica look suspiciously similar to me and I’m never really happy that two separate fungal species are involved. I must try and see if any molecular work has been done on this, especially as plums are of economic importance . . .

cheers

Chris

[JennyS]

Hi Chris – what’s the position with rusts on other prunus species as I found some (still in the microscope queue) on a hedge prunus that might perhaps be P. cerasifera ….. ?

It definitely isn’t spinosa and didn’t look like domestica either

[diggleken]

Hi Chris,

Andy did point out that T padi can be on both bird cherry and domestic plum, padus and domestica, which is what the original query was about.

Whether there is any way to differentiate in the field between the pocket plum types, T prunus and T padi, not the host as it could be either affecting the tree/bush – we’re quite happy differentiating the Prunus species.

Sorry I may well have confused……..

Cheers

Ken

[Chris Yeates]

In that case I’m confused – what is the basis for the idea that “T padi can be on both bird cherry and domestic plum, padus and domestica“? I’ve seen some records reflecting this but in the (apparent) absence of published, peer-reviewed, papers I’m sceptical.

To go back to the OP I am certain that the differences will be at the microscopical or molecular level; after all one can find such a morphological range of T. pruni on a single blackthorn bush that field characters would be unusable.

If anyone knows of any published papers I’d be interested (and surprised).

Chris

[diggleken]

Hi Chris, I cant remember where we both saw that guidance (oh dear) about variable hosts – it wasn’t Wikipedia – but I agree with you, it needs sorting, in the absence of anything specific to quote, Andy has said he will ask at Kew if they can throw any light on any differences in the field and presumably about host specificity.

When I hear anything , I’ll let you know, but don’t hold your breath.

Cheers

Ken

[pyrenopeziza]

Hi all,

This piqued my interest, so here’s some bits of the puzzle perhaps…

One paper from 2003 addressing the issue: http://ijs.sgmjournals.org/content/53/2/607.full

. It supports the phylogenetic distinction of T. padi (restricted to Prunus padus), and T. pruni (on P. domestica/spinosa (very closely related) + other close relatives), in Europe. There’s only a few sequences for each species, so although this appears to be consistent it isn’t necessarily the whole story.

Mix’s 1949 monograph (where the species were originally differentiated) can be found here, with asci figures:

Taphrina padi: http://www.biodiversitylibrary.org/page … 8/mode/1up

Taphrina pruni: http://www.biodiversitylibrary.org/page … 1/mode/1up

There are also some summaries of all of this online from 2011 in the partially available “Yeasts – A Taxonomic Study” (if you google either species you’ll find the links to this book, and the relevant pages are visible).

Mix says the two species are morphologically different, but doesn’t clarify whether this is from microscopic characters, or with regards to the disease symptoms. There could be justification in identifying them as T. pruni if the asci are very small or very big, since the size ranges are reportedly greater than in T. padi. However, I wouldn’t think this is enough proof to indicate T. pruni is on Prunus padi without other evidence. I would be even more reluctant to make the other conclusion (T. padi on Prunus domestica/spinosa) since these ascospore measurements fit within the concept of T. pruni. I personally wouldn’t be able to tell them apart microscopically from these details with any confidence, but I’m no Taphrina expert!

It might also be that Mix meant the gall morphologies were distinct, but I would suspect a lot of the morphological differences would be due to the underlying host morphology, so I wouldn’t necessarily interpret that as conclusive evidence anyway. There may be some associated disease symptoms (e.g. leaf/twig disease) that could differentiate them, but I haven’t followed that up yet. A big part of his justification (I think) is that Prunus domestica and Prunus padi are distantly related (albeit in the same genus), and since most Taphrina species are quite host-restricted then they’re probably different.

There’s also a 2000 paper that I haven’t got access to online, and I suspect it’ll be difficult to read without translation: Prillinger, H., et al. (2000) “Taphrina padi in Bayern und der Slowakei.” Hoppea 61,: 275-294.

The current state of play in published literature/Genbank seems to be the same as in the 2003 paper. I may have missed something, but there are no additional Genbank sequences other than from the 2003 paper (i.e., still only a couple for each).

Kew’s Herbtrack database of the Fungarium doesn’t seem to have any specimens that would suggest anything different to any of this.

Taphrina species do seem very highly co-evolved with their hosts, and some may possibly be systematic and generally latent endophytes of some hosts – see http://sipav.org/main/jpp/index.php/jpp … oad/173/40 ). So I would have expect the default position would be that T. padi does not occur on P. domestica unless clearly demonstrated otherwise, and the same for T. pruni and P. padus. Andy Overall’s suggestion that some on P. domestica/spinosa may be T. padi or something else may be true, but there’s no evidence to support this at the moment that I’m aware of, and given the morphological variation of the asci in Mix’s monograph I would suspect any evidence would have to be molecular or culture-based and therefore peer-reviewed and pubished.

According to the FRDBI, there’s one T. padi on Prunus spinosa (FRDBI: 1206618) , which is from Andy, and one from P. avium (FRDBI: 732709), which I suspect could be more likely to be a misinterpretation of “Bird Cherry” and really P. padus). I wouldn’t want to doubt Andy’s ID, other than I’m not convinced the microscopy can readily differentiate the two species based on current literature. I would be interested to know how he came about that ID…

I hope that helps, and please correct me if you think any of it is wrong! At the very least, the links may be useful in coming to your own conclusions.

Cheers,

Brian

[diggleken]

Brilliant synopsis Brian, gives some clarity to take forward.

I hope Andy sees this too…..

Cheers

Ken

[Andy Overall]

My ID of T. pruni on P. padus is incorrect, the collection is of T. pruni from P. domesticus (hybrid). This needs to be and will be amended in the FRDBI.

In recent communication with Paul Cannon at Kew, much of the information that Brian lays out was corroborated by him.

Microscopically and Morphologically the two species are difficult to tell apart. However, as Taphrina species are deemed as being strongly host specific, it is unlikely that T. padi would turn up on P. domesticus or P. spinosa. P. padus (its host) is in a different section of the genus. Likewise, T. pruni is unlikely to turn up on P. padus. Due to suggestions in past papers, that these two species were synonymous, confusion over hosts has arisen.

Best

Andy

[Chris Yeates]

pyrenopeziza wrote:

Hi all,

Taphrina species do seem very highly co-evolved with their hosts, and some may possibly be systematic and generally latent endophytes of some hosts

. . . .

I hope that helps, and please correct me if you think any of it is wrong! At the very least, the links may be useful in coming to your own conclusions.

Cheers,

Brian

Hi Brian

I think you mean ‘systemic’ – apart from that an excellent summing up, and I’m glad to see I was right to stick to my guns.

On a similar matter it’s interesting to see how molecular and critical morphological work by Hermann Volgmayr and others on downy mildews (and yes I know they’re not fungi) is showing that many of the former splits based on narrow host relationships which were subsequently lumped (e.g. those on clovers) are proving distinct.

Meanwhile, back at the Prunus Ranch, I’m determined to do some serious collecting of Tranzschelia discolor and T. pruni-spinosae. I seem to find a lot of intermediates/overlaps here and given that the hosts can sometimes be confusingly similar (and are as Brian has pointed out extremely close taxonomically) . . . . . . Again if anyone knows of any recent work on these two ‘species’ I’d be interested.

regards

Chris

[pyrenopeziza]

Hi Chris,

There’s been some molecular work done on the issue, but I don’t think it’s been published yet despite being done years ago.

An overall phylogeny from 2003 can be found here, which seems to be the best published molecular data for these species: http://www.ruhr-uni-bochum.de/imperia/md/content/geobot/2003/maier_2003-phylogeny-of-the-rust-fungi.pdf . Only one representative each of Tranzshelia pruni-spinosae (from Anemone ranunculoides) and T. discolor, both only in the LSU rDNA region (not ideal for species delimitation).

Some 2005 morphotaxonomic work, supposedly leading to a more detailed phylogeny which hasn’t yet appeared in published form: http://biowikifarm.net/studienstiftungswiki/media/1/13/2005_M._Abbasi_and_M._Scholler_-_A_taxonomic_revision_of_the_genus_Tranzschelia_%28Uredinales%29_-_Report.pdf

Then a 2010 conference paper which probably represents this work: Scholler M, Abbasi M, Aime MC. 2010. The genus Tranzschelia: taxonomy, phylogeny and Tranzschels law. International Mycological Congress, Edinburgh Scotland. (Abstract number U8O3) .

There are no Genbank sequences from the second two at the moment. There are lots of sequences of P. pruni-spinosae var. americana, mostly from Anemone quinquifolia from another unpublished study, which splits into three closely related main clades, one being mixed with strains identified as “T. fusca”. The sequences from the 2003 phylogeny seem distinct from both other sequences in Genbank, but I can’t be 100% sure since they were only LSU sequences and lack the ITS2 region. I wouldn’t necessarily put much trust into these identities other than saying they seem distinct species.

This UK article also should be interesting: http://www.cybertruffle.org.uk/cyberliber/59351/0080/001/0021.htm . Prunus domestica ssp. insititia (as bullace) and P. spinosa (sloe) look similar but have at least some incompatible rusts, which may or may not represent distinct species. The authors considered sloe and bullace as being very difficult to differentiate in the field, but I don’t know how true this really is. A further complication could be any hybridisations between bullace and sloe, which might affect host susceptibility. Rusts on Mirabelles might be interesting.

There’s a 2010 paper based on cross-infection studies: http://link.springer.com/article/10.1007%2Fs12600-010-0114-8 . I’ve not read it all since I’ve got no access at home, but the abstract indicates host-specific strains of T.discolor from different crops (plum, peach, apricot, almond, sweet cherry). This paper should have been backed with molecular or sequencing work, but they don’t mention anything like this, and I can’t see any sequences out there for it. Since there are only a few sequences of T. discolor, there’s no way to say if these should be considered distinct species or host-specific strains.

In summary – I think it’s still a murky area at the species level, given the lack of sequences of good representatives of these taxa and potential taxonomic compexities between the Prunus species involved. T. discolor and T. pruni-spinosae are more likely than not to be distinct species in the sense that they’re generally used, but there’s no good evidence to say which sequence is which, or how solid each species concept is. Abbasi, Scholler and Aime know more but haven’t published anything yet or uploaded their sequences, and their data may not conclusive or representative of the UK.

I’d imagine there are a few different species mixed up in the FRDBI, but I have no idea if you’d be able to differentiate them or not. If you got enough samples of these rusts and hosts from the UK, and could or couldn’t differentiate them (i.e. according to Abbasi and Scholler’s concept), then it would make an interesting sequencing project if done right. Sequencing work on the agents of crop Prunus rusts also needs to be done, and it would be interesting to see how this connects to species in the wild. At the very least, both species need proper ITS and LSU sequencing with multiple authenticated specimens to stabilise the concepts, since this is currently lacking. Whether you would be able to make anything out of it using just microscopy is another issue, but you might be able to test Abbasi and Scholler’s concept differentiating T. pruni-spinosae and T. discolor and see if it’s as clear as they say it is.

(Also, if mistyping systemic was my only obvious mistake, then that’s doing OK I reckon! :p)

I hope that helps!

Cheers,

Brian

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