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hugh.harries · hugh.harries@gmail.com | Group Owner  - Edit Membership Start a Group | My Groups
CICLY · Lethal Yellowing Disease of Coconut Palm

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Re: C I C L Y Early diagnosis of LY   Message List  
Reply | Forward | Delete Message #2087 of 2180 |
RE: C I C L Y Early diagnosis of LY

Matt

Welcome to CICLY and many thanks for giving members
the encouraging news that there are plans for
continuing research in Ghana.

Your resumé of the genetic theories of resistance
covers the essential points - but they are no more
than theories that still require testing.

The production of large F2 populations, back-cross and
even three- or four-way crosses, is technically
straightforward, using existing mass controlled
(assisted) pollination methods.

But screening large numbers of field planted palms is
not a practical possibility.

And since those theories were advanced the disease (in
Jamaica) has overcome many coconut varieties once
considered to be resistant. A more virulent strain of
LY or a more infective vector have not yet been ruled
out.

Personally, I do not think that seednut transmission
is important in nature but I accept that tissue
culture of infected embryos could be a useful tool in
any investigation.

What needs to be looked for are differences between
palm species that are immune to LY, those that simply
resist infection (but may be overcome when
environmental factors are unfavourable) and those (if
any) that tolerate infection without symptoms (death
being the ultimate symptom).

Please do not hesitate to write to
cicly@yahoogroups.com for any information. I urge
other CICLY members to respond with their own
opinions.

Regards

Hugh
====
--- Dickinson Matthew
<matthew.dickinson@nottingham.ac.uk> wrote:

Dear Hugh

Many thanks for the emails re the CICYL group, and for
putting me on the list. This is particularly helpful
and timely as I am currently putting together a full
application for BBSRC/DFID funding to carry out some
further work on seed transmission of LY and also
sustainable breeding of tolerant / resistant varieties
in Africa, based on an ongoing collaboration with
CSIR-OPRI in Ghana. This was following approval of a
concept note that I put in before Christmas.

I was therefore wondering whether you could provide me
with a bit of further help toward this proposal,
particularly on the resistance in coconuts side, as
one of the aims is to try and improve our
understanding of the genetics of resistance and
develop some tools for marker assisted breeding.

As I understand it, resistance to LY in Jamaica is
believed to be controlled by a single major
co-dominant gene locus with the influence of minor
modifier loci, whilst in Tanzania there are two or
more partially dominant genes involved. Is this still
the case, and in these breeding programmes were F2's
produced and any work done on confirming the
heritability? I know there was some attempt to develop
RAPD markers associated with resistance (Cardena et al
2003) but this was done using palms that had been
exposed to LY and had survived as the resistant
material.

My colleague in Ghana has produced WAT / SGD and WAT /
VTT hybrids that are resistant / tolerant, and we are
proposing to take these to F2, and at least look at
the segregation of molecular markers in them although
there will not be time within the project to look at
their resistance/susceptibility to disease, so we will
also be using a similar approach to Cardena to find
linked markers.

Look forward to hearing from you

Best wishes

Matt Dickinson





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Tue Jan 16, 2007 6:02 pm

Hugh Harries <harrieshc@yahoo.com>
hugh.harries
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Message #2087 of 2180 |
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Dear Hugh Many thanks for the emails re the CICYL group, and for putting me on the list. This is particularly helpful and timely as I am currently putting ...
Dickinson Matthew
dickinsonmj
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Jan 16, 2007
1:51 pm

Matt Welcome to CICLY and many thanks for giving members the encouraging news that there are plans for continuing research in Ghana. Your resumé of the...
Hugh Harries
hugh.harries
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Jan 16, 2007
6:21 pm

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