Presentation Topic

Biotechnological tools to mitigating drought in crops

DroughtA drought is a period of below-average

precipitation in a given region, resulting in prolonged shortages in its waters supply,

atmospheric, surface or ground water. A drought can last for months or years, or

may be declared after as few as 15 days.

Drought is one of the most important environmental stress affecting growth and production of crops.

Problem of arid and semi-arid regions. Most severely effected are Africa , Asia and

Australia.

Biotechnological tools to mitigating drought in crops.

These are following; Studies in model system Gene isolation, characterization and cloning Gene important in membrane transport Regulation of genes expression by drought Transgenics for abiotic stress tolerance

Biotechnological tools to mitigating drought in crops

A variety of organisms are currently used as experimental systems.

To study the molecular responses towards drought and salinity.

This includes crop plants, non crops and wild spp.

The model organisms are favourite for plant molecular biologists are mainly non crops like halophytes.

Studies in model system

The weed Arabidopsis thaliana used as model system because;

Has lower genome. It has not revealed any unique features in

investigating drought and salinity. Most of the research deals with gene

isolation and gene expression at mRNA. Mostly 70% literature on model system and

remaining 30% distributed in crop species.

Studies in model system

The isolation of gene showing altered expression of stress.

Drought stress usually elicited by withholding water and with treatment the plant stress hormone Abscisic acid.

More than 250 stress responsive genes have been isolated an studied.

Common DNA probes were used to isolate genes.

Gene isolation, characterization and cloning

Genes can be catogerised on their nature of functions in molecular biological process.

A. Regulatory genes.

B. Structural genes.

Categories of genes

Regulatory genes are; Transcription factor genes. Signal transduction genes. Structural genes are; Detoxification component genes. Fatty acid metabolism genes. Heat shock genes. Transporter protein genes.

Categories of genes

Membranes, their integral and associated components are necessary for uptake and distribution of ions and solutes.

Consider to be important determinant in developing stress resistant crops.

Transport system in both vascular system xylem and phloem is significant.

Genes important in membrane transport

Membrane transporters are complex and multimeric proteins.

Regulated by developmental, normal and other signals besides drought and salinity.

Membrane proteins are most difficult to purify and characterize.

Genes important in membrane transport

Actual functions of stress genes response to drought and salinity.

Molecular biologists are actively engaged in explaining the regulation of these genes.

Availability of sensitive DNA probes permit such investigations.

The focus on to understand the pathways of perception of stress signals in cells.

Regulation of genes expression

A great degree of success has been obtained in the production of transgenic for resistance to biotic stresses like viral and fungal.

The same has not been the case in production of transgenic for abiotic stress tolerance.

This is because of complex genetic mechanisms that governs abiotic stress.

Transgenic for abiotic stress tolerance

There are several lacunae in production of abiotic stress tolerant transgenic.

Some issues are discussed as follows;

1. It should be important to remember the goal is to get best yield under conditions of field stress.

Transgenic for abiotic stress tolerance

2. An important aspect of transgenic technology is the regulated expression of transgenes.

The promoters have been most commonly employed in the production of abiotic stress tolerant plants.

3. It is a general practice to express the transprotein in cytoplasm of transhost.

Transgenic for abiotic stress tolerance

4. As abiotic stress tolerance is controlled by polygenes.

There is need for multiple gene introduction in transgenic development.

5. Major success in the production of abiotic stress tolerant transgenic has been achieved by model plants such as tobacco.

Transgenic for abiotic stress tolerance