Green tipped woronowii

[Martin Baxendale]

Dimitri, if the green outer segment colouring (virescens) in snowdrops like Green Mile was caused by phytoplasma, surely those snowdrops with green outers would pass the infection to other snowdrops through sap-sucking insect vectors, and through mixing of sap by the hands of growers when picking flowers, propagating bulbs etc. ? But in gardens this does not seem to happen.

Can phytoplasma infection be transmitted in seed?

[Oakwood]

Dimitri, if the green outer segment colouring (virescens) in snowdrops like Green Mile was caused by phytoplasma, surely those snowdrops with green outers would pass the infection to other snowdrops through sap-sucking insect vectors, and through mixing of sap by the hands of growers when picking flowers, propagating bulbs etc. ? But in gardens this does not seem to happen.

Can phytoplasma infection be transmitted in seed?

Martin, please see here http://papilio.ab.a.u-tokyo.ac.jp/planpath/phyto-genome/what.htm

and this one short thesis as to someone gardener green-flowered snowdrop breeding programs http://www.placanet.org/archivo/_EN/Workshop_abstracts.pdf

Are phytoplasmas transmitted through seed?

Joseph Owusu Nipah1, Phil Jones2, Jennifer Hodgetts1 and Matt Dickinson1
 
1 Plant Sciences Division, University  of Nottingham, Sutton Bonington Campus,
Loughborough, LE12 5RD, UK
2 Plant Pathogen Interactions Division, Rothamsted Research, Harpenden,
Hertfordshire, AL5 2JQ, UK

The principal means of transmission of phytoplasmas between plants is by phloemfeeding insects, although there are many phytoplasmas for which the vectors have yet to be identified. In addition, they can be transmitted experimentally by plant parasitic
dodder plants and by grafting infected plant material onto healthy plants. Recently there have been reports in which phytoplasma DNA has been detected in the seed and embryos of plants such as coconuts, alfalfa, tomato, oilseed rape and lime, along with
unconfirmed reports of phytoplasmas in progeny plants from this seed. Such a mode of transmission had previously been regarded as unlikely because there is no direct connection between the phloem sieve elements of plants and the developing embryo
or seed, but there have been reports of phytoplasmas in companion cells and parenchyma cells. The possibility of seed transmission has wide ranging implications for quarantine services worldwide, since seed is not routinely tested for the presence
of phytoplasmas. In this study, we have used nested PCR to detect phytoplasma DNA in peduncles, spikelets, male and female flowers, and 9 out of 52 embryos of West African Tall coconut palms infected with Cape St Paul Wilt Disease in Ghana and
also to detect Candidatus Phytoplasma asteris DNA in kernels from infected maize plants in Peru. In germination studies, fruits from infected coconut palms had higher germination rates than those from healthy palms indicating that infected fruits retain
the ability to germinate. However, no  phytoplasmas were detected in seedlings derived through embryo in-vitro culture and we have as yet been unable to find any conclusive evidence that these pathogens are transmitted to cause disease in progeny
palms. 

regards,
Dimitrio.

edited to fix broken link
M

[Oakwood]

I rather prefer to collect and select not green but like this one nivalis form found by me in one forest in the wild in Kiev vicinities  Is it really beautiful???  that I really fear to infect it via this Chugaister one....

[Brian Ellis]

That is lovely Dimitri, I really like long petalled snowdrops and when they are swept up like that they are very attractive.

[kentish_lass]

I rather prefer to collect and select not green but like this one nivalis form found by me in one forest in the wild in Kiev vicinities  Is it really beautiful???  that I really fear to infect it via this Chugaister one....

I really like that too Dimitri - very pretty.

[Oakwood]

I really like that too Dimitri - very pretty.

well done, guys!      3:0 in favor of not-500 euro-green-flowered snowdrops!!!!!!!!!

[Oakwood]

Dimitri, if the green outer segment colouring (virescens) in snowdrops like Green Mile was caused by phytoplasma, surely those snowdrops with green outers would pass the infection to other snowdrops through sap-sucking insect vectors, and through mixing of sap by the hands of growers when picking flowers, propagating bulbs etc. ? But in gardens this does not seem to happen.

Can phytoplasma infection be transmitted in seed?

Martin - one more paper on phytoplasma transmission via seeds from here http://www.bulletinofinsectology.org/pdfarticles/vol64-2011-S157-S158calari.pdf

Molecular evidence of phytoplasmas in winter oilseed rape, tomato and corn seedlings

Alberto CALARI1, Samanta PALTRINIERI1, Nicoletta CONTALDO1, Dimitrijka SAKALIEVA2, Nicola MORI3,
Bojan DUDUK4, Assunta BERTACCINI1
1Dipartimento di Scienze e Tecnologie Agroambientali, Patologia vegetale, Alma Mater Studiorum-University of
Bologna, Bologna, Italy
2Department of Phytopathology, Agricultural University, Plovdiv, Bulgaria
3Dipartimento di Agronomia Ambientale e Produzioni Vegetali, Entomologia, University of Padua, Italy
4Institute of Pesticides and Environmental Protection, Banatska, 31b, 11080 Belgrade-Zemun, Serbia

To evaluate the seed transmission of phytoplasmas in three herbaceous hosts material from different geographical origin but all
collected from infected or symptomatic mother plants was used. Almost 1,000 seeds were germinated under controlled conditions
and 652 seedlings were obtained. Samples were grouped in 214 samples and 74 of them resulted positive to phytoplasma presence
after three to 90 days from germination by nested PCR assays on 16S ribosomal gene. All the tested species i.e. winter oilseed
rape, tomato and corn resulted carrying phytoplasmas belonging to the ribosomal groups retrieved in the infected mother plants.

[Oakwood]

Moreover, I suppose that all yellow-flowered snowdrop cultivars (e.g., Wendy's Gold, sandersii, etc...) might also be infected with phytoplasmas as this pathogen not only generates phyllodia-like perianth segments but equally impairs chlorophyll synthesis in some cases.....   


Dimitri the Evil.

[Oakwood]

Dimitri, if the green outer segment colouring (virescens) in snowdrops like Green Mile was caused by phytoplasma, surely those snowdrops with green outers would pass the infection to other snowdrops through sap-sucking insect vectors, and through mixing of sap by the hands of growers when picking flowers, propagating bulbs etc. ? But in gardens this does not seem to happen.

Can phytoplasma infection be transmitted in seed?

Martin, it could be explained quiet easily: the plant immune system effectively protects the snowdrops from pathogen invasion and potential persistence and multiplying in their tissues. BUT in very rare cases the plant innate immunity could be weakened in some exemplars that allows to the pathogen survive and effectively colonize the whole plant and their progeny both asexual (seeds) and sexual (bulbs, rhizomes, cuttings, etc.).... Diverse pathogens all deliver effector molecules (virulence factors) into the plant cell to enhance microbial fitness. Briefly, to overcome plant protection line it is not easy, but if it can be done by successful pathogen in a unique case, it chooses a strategy of complete and irreversible colonization of favorite plant entity with its further all descendants' infection..... so, the presence of a such plant in some local garden population highly increases the risk of pathogen transmission and phytoplasma syndrome expression at some rare plants in such population...
more details on a matter with described mechanisms are here http://www.nature.com/nature/journal/v444/n7117/full/nature05286.html

[MR GRUMPY]

At last here are a couple of photos(i hope?) of our green tipped woronowii.It is just a day or two from flowering this year,and this will be it's sixth year of flowering.This has been chipped,but it only makes pips not bulblets,so you will have to wait while for one of these.It is a hardy plant with me in north yorkshire and hope you all like it.

[Martin Baxendale]

Dimitri, this link doesn't work: ttp://www.placanet.org/archivo/_EN/Workshop_abstracts.pdf:

Do you have another link to this document?


edited to show correct link, as shown by alanb, below

http://www.placanet.org/archivo/_EN/Workshop_abstracts.pdf

[Martin Baxendale]

Dimitri, so basically the answer is that it's much more difficult for phytoplasmas to infect a plant than a virus, so that transmission of phytoplasma infection from one plant to another, through an insect vector or any other means of sap transfer, is much less likely to happen than transmission of a viral infection? So I could have a virescent phytoplasma infected snowdrop in my garden amongst other snowdrops for many years but the chances of that phytoplasma infection spreading to other snowdrops nearby would be quite low? Also, the chances of seedlings carrying the phytoplasma infection are low but not impossible, again because it's even less easy for phytoplasmas to be transmitted to seeds than for viruses to be transmitted to seeds (but again, not impossible).

Yet yellow snowdrops will often produce yellow seedlings if crossed with other yellow snowdrops.

Virescent snowdrops, on the other hand, do not seem to readily produce virescent seedlings (from the results of seed raising by myself and others).

I suppose you may be right about the possibility of virescens being caused by phytoplasma infections. With the yellow mark colouring, it still looks like something genetic is happening.

[Maggi Young]

At last here are a couple of photos(i hope?) of our green tipped woronowii.It is just a day or two from flowering this year,and this will be it's sixth year of flowering.This has been chipped,but it only makes pips not bulblets,so you will have to wait while for one of these.It is a hardy plant with me in north yorkshire and hope you all like it.

Great pictures, Steve !! Clear as a bell......

[Alan_b]

http://www.placanet.org/archivo/_EN/Workshop_abstracts.pdf

(remove the trailing colon).

[Martin Baxendale]

Thanks Alan, That link works.