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GRADUATE UNIVERSITY SCIENCE AND TECHNOLOGY
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LE THI MAI LINH
STUDY ON DIVERSITY OF ROOT–KNOT NEMATODES,
Meloidogyne spp., IN TAY NGUYEN HIGHLANDS
Major: Nematology
Code: pilot
SUMMARY OF BIOLOGY DOCTORAL THESIS
Ha Noi – 2019
MINISTRY OF EDUCATION
AND TRAINING
VIETNAM ACADEMY
OF SCIENCE AND TECHNOLOGY
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The thesis was completed at the Graduate University of Science and
Technology, Vietnam Academy of Science and Technology
Scientific Supervisor 1: Dr. Trinh Quang Phap
Scientific Supervisor 2: Assoc. Prof. Dr. Phan Ke Long
Review 1: …
Review 2: …
Review 3: ….
The dissertation will be defended at the Council for Ph.D. thesis, meeting
at the Viet Nam Academy of Science and Technology - Graduate
University of Science and Technology. Time: Date …… month …. 2019
This thesis can be found at:
- The library of the Graduate University of Science and Technology
- National Library of Viet Nam
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INTRODUCTION
1. Essence of the thesis
Root-knot nematodes from the genus Meloidogyne are a cosmopolitan
group of obligate plant-parasites. Meloidogyne species are able to
parasitize virtually all species of higher plants in the world. Moreover,
Meloidogyne species are considered to be an important limiting factor in
vegetable protection. So, Root knot nemaotde Meloidogyne is a serious
threat to agriculture worldwide. Till 2006, 111 species had been
decribed, in which 18 species were found on coffee.
Till 2000, five species of the genus Meloidogyne were recorded on
coffee including M. incognita, M. javanica, M. exigua, M. coffeicola and
M. paranaensis. Among five species above, M. incognita causes damage
on almost all the coffee growing areas as well as all other crops. Many
studies on coffee and pepper in Vietnam indicated that M. incognita is
the most important species causing damages. Trinh et al. (2013) also
announced the presence of two species of M. exigua and M. coffeicola on
coffee, and indicated the presence of harmful Meloidogyne species in
Tay Nguyen Highlands is pretty serious and needs to be investigated in
more detail. And, there are many species of Meloidogyne have not been
discovered and published.
Morphological analysis of perineal patterns from adult Meloidogyne
females is often used as a rapid diagnostic tool. However, there are some
major limitations with this approach, including overlapping of
morphological characters, which can lead to misidentification. Some
coffee-parasitising nematodes, such as M. izalcoensis, M. paranaensis,
and M. incognita, have the overlapping of characters related to female
perineal patterns. Additional diagnostic power can be used such as
molercular characterisation of some genes including 18S, ITS, and 28S
of rDNA and COI, COII of mtDNA.
Prevention of these nematodes species in agricultural crops mostly
based on chemical pesticides that is affecting the environment as well as
causing the loss of beneficial organisms. Moreover, using chemicals is
expensive and also depends on the activity of chemicals in the soil and
depends on country-specific rules. Therefore, searching for the solutions
to effectively control nematodes will have a great significance in the
production, contributing to limit the use of chemical drugs, safeguarding
the environment. One of the effective methods of controling this
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nematode group is the method based on the biological control of
antagonistic microorganisms that can destroy and limit the development
of nematodes.
Due to the diversity of plants and topography in Tay Nguyen, as well
as the variety of root-knot nematodes and their potential damages, we
implemented the project:: "Study on diversity of root –knot nematodes
(Meloidogyne spp.) in Tay Nguyen Highlands "
2. Objectives of the thesis
Identifying the Meloidogyne species causing damage on main
crops in Tay Nguyen Highlands
Analyze the diversity of Meloidogyne species based on
morphology and molecular classification.
Assessing the preventative ability of antagonistic
microorganisms to Meloidogyne incognita in laboratory condition.
3. Contents of the thesis
Study on distribution, frequency and density of root-knot
nematodes on some important crops: coffee, pepper, vegetables and
intercropping crops in Tay Nguyen.
Study on the morphology and diversity of root-knot nematode
Meloidogyne in Tay Nguyen.
Study on the genetic diversity of root-knot nematode
Meloidogyne in Tay Nguyen based on analyses of rDNA and mrDNA
genes.
Evaluate the prevention of Meloidogyne incognita by using some
antagonistic microorganisms such as Paecilomyces javanicus,
Lysobacter antibioticus and 4-HPAA antibiotics.
4. Scientific significance and practical meaning of the thesis
Scientific significance:
New root-knot nematodes were recorded for science not only in
Vietnam but also in global.
New morphological and molecular characters of root-knot
nematodes in Tay Nguyen Highlands were provided. Database for
sequences of Meloidogyne spp. in Vietnam is added to the International
GeneBank. Phylogeny of root-knot nematodes in Western Highlands
with Meloidogyne species in the world was created.
The opportunities to apply useful microorganisms for root-knot
nematodes control.
Practical meaning
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Exactly classifying Meloidogyne species and their density
creating a basic for effective prevetion. Providing data on parasitic
ability, hosts, damages of root-knot nematodes, preventing their spread,
avoiding early infection. Creating a basic to select appropriate farming
methods for each crop especially for coffee and pepper as well as
intercropping and rotation crops.
Providing database of morphological and molecular
characteristics of Meloidogyne spp. in Vietnam, serving as a good source
of reference.
Evaluating the antagonistic microorganisms (Pacylomyces
javanicus and Lysobacter antibioticus HS124) in preventing
Meloidogyne spp. creating a basic for selecting prevention measure,
reducing the use of harmful chemicals, maintaining ecological balance
for sustainable development of staple crops in Tay Nguyen
5. New contributions of the thesis
The thesis provided a complete data of the distribution, host and
morphological and molecular characteristics of root-knot nematode
species on coffee, pepper and intercropping plants in Tay Nguyen for the
first time. More new host plants infected with Meloidogyne nematode
have been recorded in Tay Nguyen as well as in Vietnam. Deposited 145
sequences of ITS, D2D3, COI, COII-16S, NAD5 gene regions of root-
knot nematode species from Tay Nguyen to Genbank.
A new species of root knot nematode has been recorded on
coffee that has been described, published and named by Meloidogyne
daklakensis n. sp. and 01 other new species has been described and
submitted.
For the first time in Vietnam, the ability to control Meloidogyne
incognita of Pacylomyces javanicus, Lysobacter antibioticus HS124 and
4-HPAA antibiotic was assessed in laboratory conditions.
6. Composition of the thesis
The thesis is composed of 179 pages: Introduction (4 pages); chapter
1: Literature review (22 pages); chapter 2: Methodology (13 pages);
chapter 3: Resutl and discussion (119 pages); Conclusion and
recommendation (2 pages). The thesis consists of 34 tables, 39 figures,
and 183 references. In addition, the thesis has a list of publications and
appendices