Head of male Meloidogyne
floridensis (original magnification 7,500x). Scanning electron microscope
image courtesy Zafar Handoo.
Click to view a larger version.
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Root-Knot Nematode Species
Identified By Sharon Durham August 20, 2004
A root-knot nematode species, previously unnamed and assumed to
be race 3 of Meloidogyne incognita, has now been classified
as its own species, M. floridensis.
The discovery is based on studies by an international team
including scientists from the Agricultural Research Service (ARS) in Beltsville, Md., and Byron, Ga.,
Laboratoire de Biologie des Invertébrés in France, and
Plant Research International
in the Netherlands.
The newly named nematode was isolated from nematode-resistant
Nemaguard and Okinawa peach rootstocks in Gainesville, Fla. This explains why
nematodes were infesting and reproducing in these root knot nematode resistant
rootstocks.
ARS plant pathologist Andrew Nyczepir, of the
Southeastern Fruit and Tree Nut
Research Laboratory in Byron, Ga., found the pests penchant for
nematode-resistant rootstock uncharacteristic and formed the group to conduct
various studies. Morphological, cytological, molecular and host-range studies
conclusively determined the taxonomic position of the nematode.
Through the use of a scanning electron microscope, the team, led
by ARS microbiologist Zafar Handoo of the
Nematology Laboratory in
Beltsville, Md., showed important physical differences between M.
floridensis and M. incognita.
Nyczepir used host-range testing to determine that M.
floridensis didnt exhibit the same host affinities as M.
incognita. For instance, M. floridensis reproduced abundantly on
Nemaguard and Guardian peach rootstocks, whereby M. incognita does not.
Alternately, M. floridensis doesnt reproduce in peppers as M.
incognita does.
Molecular studies confirm the uniqueness of M.
floridensis from M. incognita and other root-knot nematodes.
ARS is the U.S. Department of
Agricultures chief scientific research agency. |