GENETIC MODIFICATION OF TOMATO (Solanum lycopersicum) TO INCREASE THE UPTAKE AND TRANSLOCATION OF ZINC
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Date
2015-09-09
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK, BENGALURU
Abstract
Zinc (Zn) is one of the essential micronutrient with major biological roles both in
plants and humans. Deficiency of Zn is by far the most ubiquitous problem in the world
affecting the plant and human nutrition. Zn deficiency in humans can be addressed
through dietary diversification, mineral supplementation, food fortification and
biofortification. Among these, biofortification of food crops either through genetic
engineering or molecular breeding approaches is considered to be promising and
sustainable. To achieve this better understanding of molecular mechanisms regulating the
Zn uptake and transport in plant is most crucial. In the present investigation an attempt
was made to identify the candidate Zn transporter gene in tomato responsible for high
fruit Zn content. Initially 41 tomato genotypes were screened for Zn content. The contrast
lines identified based on the fruit Zn content were subjected for Zn deficient and
sufficient conditions and analysed for Zn transporter expression through RT- PCR. The
candidate Zn transporter genes up-regulated in the high Zn type germplasm lines, SlZIPL
and SlZIP4 were identified and cloned. Further the genes were sub-cloned to pBINPLUS
binary vector driven by constitutive promoter (CaMV35S) and the two independent gene
constructs PCaMV35S: SlZIPL: TpolyA and PCaMV35S: SlZIP4: TpolyA were used for plant
transformation. To develop transgenic tobacco and tomato plants, Agrobacterium
mediated tissue culture technique was followed. Few tobacco transgenic lines over
expressing SlZIPL and SlZIP4 showed high leaf Zn and chlorophyll content. Similarly,
tomato SlZIPL and SlZIP4 transgenics also showed high fruit, leaf and petiole Zn content
compared to wild type. Further the RT-PCR expression analysis of tomato transgenics
showed the higher expression of SlZIPL and SlZIP4. These results imply that, SlZIPL and
SlZIP4 are candidate Zn transporters in tomato involved in better Zn transport and hence
high fruit Zn content
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