Cloning and characterization of NHX1 from Indian mulberry for abiotic stress tolerance
Student name: Ms Purnima Singh
Guide: Dr Anandita Singh
Year of completion: 2013
Host Organisation: Department of Plant Molecular Biology, University of Delhi South Campus
Supervisor (Host Organisation): Prof Paramjit Khurana
Abstract: Salinity is one of the major abiotic stresses that severely affect plant growth and
productivity. A major part of land is rendered unfit for cultivation due to its
saline soil conditions. Around 19.5% of the irrigated agricultural lands are salt
affected. Mulberry is known for its major contribution in the Indian economy
through sericulture industry and for its potential use in a flavouring agent in food
industry, in medicine and as forage for animals. It is grown in the tropical and
sub-tropical regions of India, for utilization of its leaves for feeding silk worm
(Bombyx mori) for silk production. However, being moderately tolerant to
salinity stress, the productivity of mulberry is severely affected. Salinity causes
reduced number of leaves on tree, loss of turgor, cellular integrity, early
senescence, decreased photosynthesis, tissue necrosis and even death of the
plants. In the present study, mulberry NHX1 is cloned and characterized to assess
its role in conferring salt tolerance in plants. A lot of studies have already been
conducted showing that NHX1 belongs to a family of genes that regulate the
intracellular ionic balance and prevent osmotic stress. The sodium hydrogen
antiporter (NHX) gene is known for its function in removal of intracellular Na+
ions, either by its efflux or compartmentalization in vacuoles. To study the extent
of contribution of NHX1 in conferring salt stress tolerance and whether it is a
functional homologue, the gene from mulberry miNHX1 was cloned and
transformed in Arabidopsis and mulberry plants to obtain overexpression lines.
Also, a Real Time PCR based expression analysis was done to look at the fold
upregulation of the gene in various stresses. Biolistic technique was also used to
check the localization of the gene in coherence with its function.
Key words: NHX1 (sodium hydrogen antiporter), salinity stress, vacuolar
localization, mulberry (Morus indica), co-cultivation.
