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Knowledge of genetic diversity has been successfully used for efficient germplasm
management and utilization, genetic fingerprinting and genotype selection (FAO, 1998). The study
of phenotypic and genetic diversity to identify groups with similar genotypes is important
for conserving, evaluating and utilizing genetic resources further for developing new crop
varieties and for determining the uniqueness and distinctness of the phenotypic and genetic
constitution of genotypes with the purpose of protecting a breeder's intellectual property rights
(Maric et al., 2004).
Since Jatropha is an exotic introduced in India, the diversity prevailing among the
local population is debatable. Thus in India, the genetic background of the physic nut grown
is unclear and the extent of genetic variation prevailing in these areas is not known. A
prerequisite for genetic variation studies is the ability to isolate DNA of adequate quality and
quantity. Purified genomic DNA required for many applications in molecular genetics is frequently
more difficult to obtain from trees than from most other plants. DNA yield and quality often
vary among species of the same genera and among tissues from the same tree (Henry, 2001).
Problems with extracting tree DNA are due to impurities such as terpenes,
polyphenolics, and polysaccharides, which are often abundant in the foliage of perennials and coextract
with DNA. As a consequence, many tree species require more complex extraction methods
than do annual plants, requiring special grinding procedures (Scott and Playford, 1996) or
an initial organelle isolation step under acidic conditions (Graham et al., 1994; and Guillemaut and Marechal-Drouard, 1992). Like many other species, Jatropha contains high levels of polysaccharides. Polysaccharides interfere with the polymerase chain reaction (PCR)
by inhibiting Taq polymerase activity (Fang et al., 1992). In this context, the present study
aims at optimization of DNA extraction procedures from Jatropha curcas for PCR-based DNA marker studies. |
