GENETICALLY MODIFIED CROPS

PRESENTATION ONADVANTAGE OF GENETICALLY MODIFIED FOOD (DROUGHT RESISTANCE CROP)

PRESENTED BY DR.VEENA KUMARI PHD SCHOLAR

GENETICALLY MODIFIED CROPSGeneticallymodifiedcrops( GMcrops, or biotechcrops) areplantsused in agriculture, the DNA of which has been modified usinggenetic engineeringtechniques. In most cases, the aim is to introduce a new trait to theplantwhich does not occur naturally in the species.

DROUGHT RESISTANT CROPS

We humans depend on plants for our survival. The oxygen we breath comes from plants, as does the food we eat and the feed animals we eat.With a global population expected to reach 9 billion by 2050, a limited food supply for growing population.Adverse environmental factors, of which water scarcity represents the most severe constraint to agriculture, account for about 70 percent of potential yield loses worldwide.

Agriculture is the largest consumer of water in the world, and in the drier areas of the world, which include many developing countries, the use of water for agriculture can exceed 90 percent of consumption.Global warming is also predicted to affect most severely developing countries, where agricultural systems are most vulnerable to climatic conditions.

Developing Drought Tolerant Crop

"Conventional breeding" Conventional breeding referring to "anything that's not genetic modification," which includes mutational breeding, doubled haploid breeding, and inter specific hybridization - all of which regularly require laboratory intervention.

During Conventional plant breeding genes are mixed and newly assorted. This results in non-desired traits being inherited together with the trait of interest. GM techniques and conventional techniques are not mutually exclusive. In fact, GM techniques require conventional breeding to be of any practical success.Cont:

Conventional breeding requires the identification of genetic variability to drought among crop varieties or among sexually compatible species.Conventional breeding for drought tolerance continues to have some success, it is a slow process that is limited by the availability of suitable genes for breeding.

Some examples of conventional breeding programs for drought tolerance are the development of rice, wheat and Indian mustard varieties tolerant to salt and to alkali soils by the Central Soil Salinity Research Institute in Karnal India.

Plant Drought Tolerance MechanismsThe physiological responses of plants to a deficit of water include leaf wilting, a reduction in leaf area, leaf abscission, and the stimulation of root growth by directing nutrients to the underground parts of the plants.Plants are more susceptible to drought during flowering and seed development (the reproductive stages).CONT:

Abscisic acid (ABA), a plant stress hormone, induces the closure of leaf stomata (microscopic pores involved in gas exchange), thereby reducing water loss through transpiration, and decreasing the rate of photosynthesis. These responses improve the water use efficiency of the plant on the short term.

The plants response to drought is accompanied by the activation of genes involved in the perception of drought stress and in the transmission of the stress signal.One group are genes that encode proteins that protect the cells from the effects of desiccation.A second group of genes activated by drought is comprised by regulatory proteins that further regulate the transduction of the stress signal and modulate gene expression.

At least four independent stress-responsive genetic regulatory pathways are known to exist in plants, forming a highly complex and redundant gene network. Two of the pathways are dependent on the hormone ABA, and two are ABA-independent. These pathways are also implicated in the perception and response to additional stress factors, including cold, high temperature and salinity.

Genetic Engineering Drought Tolerant PlantsGenetic modification" in modern usage is synonymous with transgenic or genetically engineered. It involves the insertion of specific designer genes into a plant's genome through laboratory techniques, typically with modifiedAgrobacteriumor biolistics (gene gun).CONT

Genetic engineering, on the other hand, requires the identification of key genetic determinants underlying stress tolerance in plants, and introducing these genes into crops.

The introduction of several stress-inducible genes into plants by genetic engineering has resulted to increased tolerance of transgenics to drought, cold and salinity stresses.The plant hormoneAbscisic acid(ABA) is the major player in mediating the adaptation of the plant to stress.

A gene identified inArabidopsis, encodes the -subunit of a farnesyl-transferase, and is involved in ABA signaling.ABA levels in the plant greatly increase in response to water stress, resulting in the closure of stomata thereby reducing the level of water loss through transpiration from leaves and activate stress response genes.The reaction is reversible,

Root traitsGeneticists and breeders are positioned to breed plants with Root traits that improve productivity under drought.Root traits associated with maintaining plant productivity under drought include( small fine root diameters, long specific root length, and considerable root length density, especially at depths in soil with available water).

In environments with late season water deficits, small xylem (the vascular tissue in plants which conducts water and dissolved nutrients upwards from the root) diameters in targeted seminal roots save soil water deep in the soil profile for use during crop maturation and result in improved yields.Capacity for deep root growth and large xylem diameters in deep roots may also improve root acquisition of water when ample water at depth is available.

Xylem pit anatomy that makes xylem less leaky and prone to cavitation , such traits may improve plant productivity in water-limited environments without negatively impacting yield.Rapid resumption of root growth following soil rewetting may improve plant productivity under episodic drought.

Screening of root traits at early stages in plant development can proxy traits at mature stages but verification is needed on a case by case basis that traits are linked to increased crop productivity under drought.

Germplasmis the living genetic resources such as seeds or tissue that is maintained for the purpose of animal and plant breeding, preservation, and other research uses.In addition to coarse seminal roots, nodal roots (or brace roots in maize,Zea mays) developing from lower portions of the stem provide additional opportunities for plant foraging of late-season precipitation with different responses to soil water .

Fine (or lateral) roots are the most active portion of the root system in water uptake, and comprise the majority of the length and surface area of these root systems.

An Australian wheat (Triticum aestivum) breeding program successfully developed wheat varieties with more conservative hydraulic architecture in seminal roots to save soil water under drought for critical stages in crop yield development later in the field season.

Plant Breeding Methods for Drought ResistanceBreeding for drought resistance, refers to breeding for yield under soil moisture stress condition.it refers to yield improvement in environment represented by water deficit. Four breeding methods are 1) Introduction: In self pollinated crops. 2) Selection: pure line selection, mass selection.CONT

3) Hybridization: Pedigree method and backcrossing. 4) Mutations are commonly used for development of drought resistant crop cultivars, breeding are used.When the drought resistant genotypes are available in the land races or mixed populations, either pure line selection or mass selection is adopted.

When the resistant genes are available in the germplasm , the breeder has to resort to hybridization.Mutation is used when the desired genes are not available in the germplasm.

Simple screening was effective in selection of drought resistant characters in one genotype. Screening of material under drought conditions, use of large population in yield test and testing at several locations will help in selection of superior lines.

PLANT TRANSFORMATION USING PARTICLE BOMBARTPARTICLE BOMBARDMENT / Particle Gun/ Particle Acceleration/ Micro projectile Bombardment: Professor Sanford and collegues at Cornell university( USA) developed the original Bombardment concept in 1987 and coined term Biolistic for both process and device.It employs high velocity micro projectile to deliver substances into cells and tissues.

USES:This method is commonly employed for genetic tranformation of plants and many organisms.Method is applicable for the plants having less regeneration capacity and those which fail to show sufficient response to Agrobacterius mediated gene transfer in Rice , Corn , Wheat, Chickpea, Sorghum, and Pigeon Pea.

Appartus:Agene gunor a biolisticparticledelivery system, originally designed for plant transformation, is a device for delivering exogenous DNA (transgenes) to cells. The payload is an elementalparticleof a heavy metal coated with DNA (typically plasmid DNA). Thistechniqueis often simply referred to asbiolistics.

This device is able to transform almost any type of cell, including plants, and is not limited to transformation of the nucleus; it can also transform organelles includingplastids.Gene gun was originally aCrosman air pistolmodified to fire dense pallets of gold or tungstenparticles,Pallets are coated in DNA , transferred to the new organism,

Pallets are loaded into gene gun barrel,bullet made up of plastic and it is goes down the gun barrel become coated in the pelltes,At the end of barrel , the plastic bullet hits a metal sheet with a small hole,Pallets move away at a very high speed as enter the cell.

The transfer DNA contain genes encoding for desired trait and also for antibiotic.Then cell are grown on a dish with the medium, if insertion was succesful , then cell will grow.