Genetic Diversity of Halophilic organism in Chinese Salt lakes and application prospect for plant salt resistant genetic engineering

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Genetic Diversity of Halophilic organism in
Chinese Salt lakes and application prospect for
plant salt resistant genetic engineering
Fanjing Kong R D Center of Salt lake and
Epithermal Deposits,CAGS
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Main Contents 1. Outline of Chinese salt lakes 2.
Genetic diversity of halophilic organism in
Chinese salt lakes 3. Main methods and strategy
to clone genes
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Four salt lake regions distinguished (I). the
Qinghai-Tibet Plateau Region (II). the
Northwestern Region (III). the North-Central
Region (IV). the East Region
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Quaternary saline lake regions in China(After
Mianping Zheng,2001)
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Characteristics of chemical composition type 1.
All types of chemical composition are present in
Chinese salt lakes 2.From the quaternary
arid center of Qaidam Basin- Tarim Basin outwards
the following zones occur a chloride-sulphate
subtype zone, a chloride-bearing Mg-sulphate
subtype zone or Na-sulphate zone, and a carbonate
type Na-sulphate subtype or carbonate type
zone 3.Some are except which reflect the
influence of complex local geographical and
geological conditions
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Distribution of salt lakes according chemical
types in China (After Mianping Zheng,1993)
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Methods of the genetic diversity study Random
Amplified Polymorphic DNA (RAPD) Restriction
Fragmental Length Polymorphism (RFLP) DNA
Amplified Fingerprinting (DAF) Amplified
Fragmental Length Polymorphism (AFLP).
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The Genetic diversity of halophilic bacteria was
studied by RFLP
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Halophilic bacteria analyzed by16 S r DNA
PCR-RFLP 28 moderately halophilic bacteria
isolated from salt lakes in Xinjiang Regions
analyzed The results showed that all tested
strains were cluster into three groups at 74
similarity level. Group I included two reference
strains, Chromohalobacteria marismortui,
Nesternkonia halobia and new isolate C1. Group
II included seven type strains belonging to
Halomonas and eight new isolates. Group III
included nineteen new isolates
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Dendrogram of halophilic bacteria in Xinjiang
Region
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Table 1 The new halophilic microorganism species
from Chinese Salt lakes
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The genetic diversity of Artemia was studied by
AFLP
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Table 2 The Artemia strains for the AFLP analysis
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The result with 12 primer combinations showed
that 594 bands were detected, and 480 bands are
polymorphic. The polymorphic level was
31.819-55.10. Average bands for 1 pair are 49.5.
The genetic distance ranged from 0.069-0.678,
average 0.423 The result demonstrated that the
genetic diversity among Chinese Artemia was very
rich.
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Table.3 Genetic distance based on AFLP data of 15
strains of Artemia
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Dendrogram Of Artemia in Chinese salt lakes based
on AFLP data (After Yi Sun, 2000)
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The plant genetic engineering for salt
resistance 1. Cloning of the salt resistance gene
2. constructs of target gene with vector 3.
transformation 4. Identification of
transgenetic plants. The key step is the cloning
of salt resistance gene.
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The main methods and strategy to clone gene Map
Based Cloning Transposon Tagging Difference
Display Gene Chip
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Map Based Cloning Three main factors should be
prepared 1.high destiny physical maps and
molecular markers linked tightly with aimed gene
2.clones with large insert DNA fragment 3.
efficient transformation system.
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The steps of map based cloning 1.identify a
molecular marker that lies close to targeted
gene. 2. saturate the region around that original
molecular marker with other markers. 3. screen a
large insert genomic library (BAC or YAC) with
your marker to isolate clones that hybridize to
molecular marker. 4.The steps that follow are
termed chromosomal walking.
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Differential Display Differential Display was
invented in 1992 by Drs. Arthur Pardee and Peng
Liang to allow rapid, accurate and sensitive
detection of altered gene expression
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Differential Display comparaed with other methods
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Gene chip Traditional methods a "one gene in one
experiment" basis, throughput is very limited
the, "whole picture" of gene function is hard to
obtain. Gene chip promises to monitor the whole
genome on a single chip a better picture of the
interactions among thousands of genes
simultaneously.
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Gene chips are fabricated by high-speed
robotics, generally on glass but sometimes on
nylon substrates, for which probes with known
identity are used to determine complementary
binding, thus allowing massively parallel gene
expression and gene discovery studies.
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Summary 1. Most Chinese salt lakes occur in the
west and northeast. They belong to many types
according to their chemical composition. 2. The
genetic diversity of halophilic organisms in salt
lake may provide gene resource for genetic
engineering . 3. The strategy and methods for
cloning gene are map based cloning, difference
display, transposon tagging, DNA chip.