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CICLY · Lethal Yellowing Disease of Coconut Palm

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Fwd: C I C L Y News from Jamaica   Message List  
Reply | Forward | Delete Message #2147 of 2180 |
Re: C I C L Y News from Jamaica

Dagmar, Hugh,

Cicly members who are doing research on some difficult problems like the lethal yellowings of coconut cannot spend their time in front of their computer... They generally think they have too much messages to read… specially when they are back from a survey! That is the main and good reason why they don’t comment all the messages published on Cicly. Anyway, this question on LY destroying presumed “resistant varieties or hybrid” for sure was important enough for us, to look at what could be the cause of these losses. The question was put on the table at the CFC/FAO meeting on LY in Jamaica in 2002.

What is called the “new outbreak” of LY Jamaica, in fact, is not new any longer. It started at the end of the 80s in Florida. (Howard et al. 1987, J. Plantation Crops, 15 : 86-100. Unusually high lethal disease incidence in Malayan Dwarf coconut plams…). They reported that “ losses ranged from 42.9 to 100%”. This was confirmed by Broschat et al. in 2002 ( Palms, 46 :185-189 : Losses to lethal yellowing cast doubt on coconut cultivar resistance). In this article it is written: “Losses of 74 of the 106 Malayan Dwarf (70%) and 10 of the 12 hybrid Maypan –Malayan Yellow Dwarf x Panama Tall-  (83%) to the disease.” These data concerned trees planted in 1982. LY became active on these palms from the mid 1980’s (on 5 years old coconuts) until about 1999. “Malayan Dwarf” were Green, Yellow and Red Dwarf from Jamaica.
These events occurred about 4 years after the publication of Basil Been in Oléagineux (Been , 1981, 36 : 9-12). Anyone reading carefeully this article could see that Malayan Dwarf varieties in
Jamaica were not “immune”. According to the different places where they had been planted between 1962 and 1970, at six trials sites, the % of losses after 9 to 17 years was between 0 (in Orange River, on 29 trees)  to 11% (in Caenwodd, on 96 trees). Average for Jamaica was  4%.For the hybrid Maypan the losses were betwenn 4% (in Kildare, on 67 trees )  and 21% (in Caenwood on  39 trees). Average :10%

For such a disease three components must meet : the host; the inoculum, the vector. It is known that  the presumed vector in the Carribean –America (Myndus crudus) is present as far as Brazil and Colombia. But there is no LY south of Nevis, on the East border, and South of Honduras, on the West border. The inoculum must not be present. In Jamaica there are a lot of valleys downwards the central mountains. Most of them are isolated from the next one. Then it is possible the LY developed in one valley and not in the next one (This was clear at the end of the 90’s beginning of the 2000’s). It means that perhaps inoculum was pesent in some trials sites  and  absent or rare in the others. So, perhaps the vocabulary adopted in the 70’s was not the best one. As a matter of fact varieties were desigend as “Highly resistant” when the average mortality in Jamaica was less than 15%  after 9 to 17 years. But 21% of the  Maypan were killed in caenwood. Or people have used the terms “higly resistant” as “resistant” while in fact they were “less attacked”,  or “later attacked”  than other varieties such as the local Jamaica Tall. But I don’t wish to come back on the eternal debat of what means resistant and tolerant in phytopathology…

To go further on this aspect of “ presumed resistant varieties or hybrids” killed by the disease, Cirad and the Coconut Industry Board, undertook a research on the molecular characterization of the Malayan Yellow Dwarf  from Jamaica, used to produce the hybrid . The results are that most of these MYD are not “true MYD” (compared for instance to the MYD of the Marc Delorme germplasm collection in Côte d’Ivoire where 100% of the MYD have the same molecular –microsatellites-  pattern. The results have been submitted to publication, in Tree Genetics & Genomes , in May 2006 accepted after two successive revisions and accepted in March 2007. Only this week I got the permission of the Editor to post the abstract on the Web. (No news on when it will be published… it is also why we have no time to comment Cicly messages).

Here is the abstract :

Malayan Yellow Dwarf Coconut no longer resistant in Jamaica?

P. Lebrun, L. Baudouin, W. Myrie, A. Berger, M. Dollet.

Abstract

 In Jamaica, the MAYPAN, a hybrid of Malayan Yellow Dwarf (MYD) and Panama

 Tall coconut, previously considered highly resistant, is currently being devastated by an

epidemic outbreak of lethal yellowing disease (LY). There are several possible causes

for this change. In this study, we checked that affected planting material in Jamaica is

genetically the same as the material shown to be resistant. We compared the DNA of

MYD sampled in four locations in Jamaica with a reference DNA of the same cultivar

collected in five different countries. The results of our analyses showed more variation

at 34 SSR loci in Jamaica than in the rest of the world providing clear evidence for the

presence of about 10% of alleles that do not match the usual typical MYD genotype.

These alleles appear to have already been present in the introduced germplasm. This

rules out a possible cause of the new outbreak: the observed heterogeneity may have

caused some loss of resistance, but is insufficient to explain a massive outbreak of the

disease.

 

(A similar work was done on Panama Tall and was submitted for publication in January 2007 and we are still waiting news from the Editor!...)
 

As it is written, these results alone cannot explain the “new outbreak”. We try to work on the two hypotheses :

-         change in the “strain” of the LY phytoplasmas involved in LY in Jamaica and Florida . But there is a very difficult gap in this research : there is no isolated Phytoplasma DNA from the 60’s.

-         change in the vector populations, but, as it was seen in the 70’s and 80’s in Florida and Jamaica, research on the vector is not an easy and short task.

I hope these informations will be useful.

Regards.

Michel Dollet
Head Research Unit "Coconut lethal Yellowings and Citrus greening"

CIRAD-BIOS
TA A29/F
Campus International de Baillarguet
34398 Montpellier Cedex 5
France

Tel: 33 (0)4 67 59 39 22
Fax: 33 (0)4 67 59 38 19
Research Unit Coconut Lethal Yellowing and citrus greening Web Site





Dagmar Hanold a écrit :
Thanks for this, Hugh!

I am the 'plant moderator' for www.promedmail.org, an information service by the International Society for Infectious Diseases. Since I didn't get any replies to my questions, I decided not to wait any longer and have just posted the Jamaica item on LY - it should be on the web today or tomorrow. Perhaps you could check it out and let me know what you think.

I would be very happy to run a follow-up story including some of your remarks below - I think breakdown of resistance is a very important and scientifically interesting question. If you prefer I could make something up out of what you have written below, but it would be really fantastic if you would like to prepare a small item to be posted directly.

Please let me know if you think this is a good idea.

Thanks again for your help! Looking forward to hearing from you again,

Dagmar


On 22/05/2007, at 8:17 AM, Hugh Harries wrote:

Dagmar

It seems I was wrong to think that CICLY members might
have an opinion on your question "does this . . . mean
that dwarf and hybrid resistance has broken down?"

It is their interest in lethal yellowing disease that
appears to have broken down. But just wait until
another Latin American and/or West African country
becomes host to the next epidemic outbreak!

My own opinion is that because there have always been
examples of individual dwarf and hybrids dying from LY
they all vary in their level of resistance. None are
immune and when infection does occur none live long
enough to be called tolerant.

Resistance and susceptibility are like the two faces
on a spinning coin - which way it lands depends on
external circumstances.

So what happens when more than a few - perhaps most
dwarf and hybrid varieties in Jamaica die from LY
while some countries - Cuba and Dominican Republic -
can co-exist with this disease and another country -
Ivory Coast - remain free even when it is on their
border with Ghana for years?

It must be the external circumstances.

What has changed in Jamaica since the successful 60s
and 70s? Has the phytoplasma mutated? Has the vector
become more effective? Has another vector joined the
attack?

I don't suppose CICLY members have opinions on these
possibilities either.

But just wait until another Latin American and/or West
African country becomes host to the next epidemic
outbreak!

Regards

Hugh
====

--- Dagmar Hanold <dagmar.hanold@adelaide.edu.au>
wrote:

> Hello all,
> I would appreciate any comments or information on
> the issue below.
> Thanks and regards,
> Dagmar Hanold
>
> Begin forwarded message:
>
> > From: Hugh Harries <harrieshc@yahoo.com>
> > Date: 10 May 2007 3:17:45 PM
> > To: Dagmar Hanold <dagmar.hanold@adelaide.edu.au>
> > Subject: Re: C I C L Y News from Jamaica
> >
> > Hi Dagmar
> >
> > It is still a matter of opinion. Why don't you
> send
> > your question to cicly@yahoogroups.com to generate
> an
> > exchange of opinions?
> >
> > Hugh
> >
> > --- Dagmar Hanold <dagmar.hanold@adelaide.edu.au>
> > wrote:
> >
> >> Dear Hugh,
> >>
> >> I may have missed previous stories on this - but
> >> does this paragraph
> >> below
> >>
> >>>> It says the continued failure is linked to
> >> farmers' reluctance to
> >>>> plant the Malayan Dwarf and Maypan hybrid,
> which
> >> are still dying from
> >>>> lethal yellowing disease.
> >>
> >> mean that dwarf and hybrid resistance has broken
> >> down?
> >>
> >> Kind regards,
> >> Dagmar Hanold
> >>
> >>
> >>
> >>> From: "hugh.harries" <harrieshc@yahoo.com>
> >>> Date: 6 May 2007 4:48:28 PM
> >>> To: CICLY@yahoogroups.com
> >>> Subject: C I C L Y News from Jamaica
> >>> Reply-To: CICLY@yahoogroups.com
> >>>
> >>> "Sat May 5, 2007
> >>> Farmers' reluctance stymies efforts to re-grow
> >> coconuts
> >>>
> >>> The Coconut Industry Board, which is staging
> the
> >> annual general
> >>> meeting of the Growers Association on Saturday,
> >> has indicated that it
> >>> is experiencing problems with its planting
> >> programmes.
> >>>
> >>> It says the programmes introduced as part of
> >> efforts to maintain the
> >>> number of trees which existed immediately
> before
> >> the latest outbreak
> >>> of yellow leafing in 1997 have seen little
> >> success.
> >>>
> >>> According to the Board, it did not achieve its
> >> targeted planting of
> >>> 100,000 seedlings per year, and this has been
> the
> >> experience every
> >>> year since the establishment of the programmes.
> >>>
> >>> It says the continued failure is linked to
> >> farmers' reluctance to
> >>> plant the Malayan Dwarf and Maypan hybrid,
> which
> >> are still dying from
> >>> lethal yellowing disease.
> >>>
> >>> Planting under the old programme should have
> >> ended in 2004, but the
> >>> Board decided that the period should be
> extended.
> >>>
> >>> This, as the targeted 300,000 seedlings over
> the
> >> five years had not
> >>> been achieved.
> >>>
> >>> Under the programme, the Board is continuing to
> >> offer 60,000 seedlings
> >>> per year and fertilizer for 80 per cent of the
> >> seedlings."
> >>>
> >>>
> >>
> >
>
http://www.rjr94fm.com/news/story.php?category=2&story=35569
> >>>
>
> Dr Dagmar Hanold
> Plant Virology
> School of Agriculture, Food and Wine
> The University of Adelaide, Waite Campus
> Glen Osmond SA 5064, AUSTRALIA.
> Tel: +61 8 8303 7307; Fax: +61 8 8303 7109.
> E-mail: dagmar.hanold@adelaide.edu.au
> website:
>
http://www.agwine.adelaide.edu.au/research/plant/path/pv
> CRICOS Provider Number 00123M
> _________________________________________________

__________________________________________________________
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Dr Dagmar Hanold
Plant Moderator, ProMED-mail




--
Michel Dollet
CIRAD-BIOS
TA A29/F
Campus International de Baillarguet
34398 Montpellier Cedex 5
France

Tel: 33 (0)4 67 59 39 22
Fax: 33 (0)4 67 59 38 19
Research Unit Coconut Lethal Yellowing and citrus greening Web Site



Tue Jul 24, 2007 10:29 am

DOLLET Michel <michel.dollet@cirad.fr>
michel.dollet@cirad.fr
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Hello all, I would appreciate any comments or information on the issue below. Thanks and regards, Dagmar Hanold ... Dr Dagmar Hanold Plant Virology School of...
Dagmar Hanold
dagmar.hanold@adelaid...
Send Email
May 10, 2007
1:41 pm

Dagmar It seems I was wrong to think that CICLY members might have an opinion on your question "does this . . . mean that dwarf and hybrid resistance has...
Hugh Harries
hugh.harries
Offline Send Email
May 21, 2007
11:50 pm

Thanks for this, Hugh! I am the 'plant moderator' for www.promedmail.org, an information service by the International Society for Infectious Diseases. Since I ...
Dagmar Hanold
dagmar.hanold@adelaid...
Send Email
May 23, 2007
7:18 am

Dagmar Your ProMed-Mail seems very comprehensive and I hope other CICLY members will find it at http://tinyurl.com/2djc7d I agree that it would be a good idea...
Hugh Harries
hugh.harries
Offline Send Email
May 24, 2007
8:35 am

Dagmar, Hugh, Cicly members who are doing research on some difficult problems like the lethal yellowings of coconut cannot spend their time in front of their ...
DOLLET Michel
michel.dollet@cirad.fr
Send Email
Jul 24, 2007
4:31 pm

Hello Michel, Thank you very much for this information, it is most interesting. Do you think it would be ok if I did a follow-up story posting your abstract...
Dagmar Hanold
dagmar.hanold@adelaid...
Send Email
Jul 25, 2007
8:52 am

... Cicly members who are doing research on some difficult problems like the lethal yellowing of coconut cannot spend their time in front of their computer... ...
Hugh Harries
hugh.harries
Offline Send Email
Jul 26, 2007
12:55 pm

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