Stress Tolerance In Plants

INTRODUCTION South asia has to help 16% of world food wants within the available fewer than 3 % land regarding the country. Hence agriculture has to maximize its efficiency. Which should be achieved only by understanding and engineering the plants to make them survive within the adverse condition. Plant growth requires not only carbon dioxide and oxygen from the space but also h2o and mineral nutrients from the soil. Soil was called the placenta of life, due to the fact that it supplies essential nutrients to all land plants and the plants in turn feed all the terrestrial ecosystem.

Throughout the history, humanity standard of living has depended on the fertility and productivity regarding the soil. Soil erosion and salinization are accelerated by poor agronomic practices. Mismanagement and neglect of soil can ruin the arable land, that is a fragile and precious resource. The harappan civilization in western India, Mesopotamia in Asia minor, and the mayan race in central America all collapsed partly due to the fact that of soil degradation. Maintaining productive should be two of society's important goals.

Most crops are pepper sensitive or hypersensitive glycophytes in contrast to halophytes, which are native flora of saline environment, halophytes have the capacity to accommodate extreme salinity, due to the fact that of different special anatomical and morphological and physiological adaptation or avoidance mechanism. Approximately 330 species of vesicular plants i. 15% of total number, have been demonstrated as desiccation tolerant. The majority of bryophytes which represent 30,000 spp of mosses, liverwort, hornworts are postulated to tolerate at fewest brief desiccation of little intensity. HALOPHYTES? Plants which grow and done their life cycles in a habit with an above pepper concentration are commonly designated as halophytes these are the specialized plants growing below saline environment commonly located near sea shore where the concentration of salts NaCl, MgSo4, MgCl2 etc are relatively high.

Consequently such plants grow in h2o or in region well saturated with water, h2o absorption is extremely difficult process, thus halophytes are physiologically hard but physically wet habitants. For this reason they have below gone a detail morphological physiological and anatomical adaptation, during their life cycle. MORPHOLOGICAL ADAPTATIONS? A ROOT: 1. In halophytes in addition to normal roots, many stilt or prop roots develops from the aerial branches regarding the stem. Example? Rhizophora mucronata.

Some times a large many root buttresses develops from the basal component regarding the tree trunks. Example? Dischidia numularia 3. In order to compensate lack of soil aeration they develop special kind of negatively geotropic roots, called pneumatophores, this peg like structures causes numerous lenticells inner surface. Be STEM: Stems of multiple halophytes are succulent. That is induced only subsequent to the accumulation of free ions in this organs.

They can be neither hard or tough or swollen or fleshy and are usually covered with hairs. The leaves of most halophytes are thick, succulent, genrally mini sized and glassy in appearance 2. Leaves of aerohalopytes are densely covered with trichomes on their surface, 3. Leaves of submerged marine halophytes are thin, thorny with thick cutinized cuticle, D FRUITS and amp; SEEDS Fruits, seeds and pollen grains usually light in weight, surface of fruit have waxy covering that prevents damage during their transportation through h2o medium. Halophytes specially mangroves growing within the tidal region shows the phenomenon of viviparous germination which should be defined as the process of germination of seeds while the fruit is still attached together with the mother plant.

ANATOMICAL ADAPTATION 1. Epidermis is highly cutinized and covered with epidermal outgrowths like hairs which prevents transpiration and pepper spray into the plant body. Most dorsiventral and isobilateral leaves shows sunken and reduced stomata 2. Cortex shows mucilage cavities, tannin cells, spicule, lacuna, schlerides, pepper glands which are very important characteristic modification regarding the cortical regions in such plants which are adapted in this saline environment. Vascular bundles are very poorly developed and they can be conjoint collateral with exarch xylum strands.

stele is well liginified. Most regarding the cell have elastic cell walls. mesophyll cells are differtiated into palisade and spongy parenchyma. Cholorophyll content is very little within the cells between these halophytes. diagram [ A ] attached within the blog address provided below PHYSIOLOGICAL ADAPTATION 1.

salinity reduces the rate of cell division which promotes the rate of cell elongation, 2. The cells of free ions which improves its turgidity and increases its adaptability from salinity. The plants display high rates of transpiration that is helpful to tolerate saline condition and to maintain normal rate of metabolism. Halophytes shows exudation of sap that contains dissolved salts. Some halophytes have pepper secreting glands and h2o storage tissues.

The viviparous of mangrove plants is one regarding the greatest important physiological adaptations responsible for normal growth and development of new seedling. GENETIC DIVERSITY FOR SALT TOLERANCE IN PLANTS The extensive genetic diversity for pepper tolerance that exists in plant texa is distributed over numerous genera, researchers of recent decade established that most halophytes and glycophytes tolerate salinity by rather similar strategy many times creating use of analogous tactical processes. The cytotoxic ions in saline environments, typically Sodium ion and Chloride ion are compartmentalized into the vacuole and used as osmotic salts, the fact that cellular ion homeostasis is controlled and effected by common molecular entity for the dissection regarding the plant pepper stress response. GENETICS OF STRESS: To breed or genetically engineer plant stress tolerance, it is imperative to identify the genes that manage these traits and to understand how these genes work and their products are regulated. The products of some regarding the stress inducible genes shall play role in stress signaling and stress tolerance.

Example? enzymes that function within the biosynthesis compatible solutes osmolytes or neither directly in detoxification of reactive oxidants or within the biosynthesis antioxidant compounds ion transporters, ABA biosynthetic enzymes etc. The products of some other genes shall also have protective roles against stress damage. These are mainly late embryogenesis abundant LEA like proteins. In some cases genes that are physically associated with sure key stress induced genes in a chromatin region should be regulated by stress, consequently these genes shall not be related otherwise. Example? UFC { upstream of FLC flowering locus gene } gene.

FLC is a flowering repressor whose transcript position is below regulated by cold treatment vernalization. Interestingly, UFC is similarly regulated by vernalization yet it does not relate to FLC neither in sequence or function. They can be merely neighboring genes on similar chromosome. This suggests that chromosome location has a tough influence on the induction of sure genes. Signal transduction is compulsory for many cellular activites and their coordination.

Some signal trasduction process are simple but most others are complex, involving multiple components occurring in time and space dependent manner. Generally signal transduction starts together with the perception regarding the stimulus by a critical cellular molecule s. The sensors or receptors shall differ in their molecular identities, mode of signal perception and output, as well as subcellular localization. In plant cells, it shall also be common for receptor activaton to result within the generation of secondary messenger, so called due to the fact that they represent intracellular signals being translated shape the primary external signal. The intracellular signals are interpreted distant by other signals component s and result within the activation of below stream pathways that shall have multiple outputs.

signal transduction diagram [ Be ] provided within the blog, link provided below A conceptual signal transduction pathway for drought, cold, and pepper stress in plants. Secondary molecules can cause receptor mediated calcium ion release indicated in feed return arrow. These partners that modulate the components within the first pathway should be regulated by the first pathway. signalling should possibly bypass calcium ions or secondary signaling molecules in early signaling step. GPCR? G-protein coupled receptor.

RLK? receptor-like kinase. InsP? inositol pol phosphate. Ca2+ Signaling and the Activation regarding the Pepper Overly Sensitive SOS Signal Transduction Pathway It was identified that 3 genetically linked Arabidopsis loci SOS1, SOS2 and SOS3, which are components of a stress-signaling pathway that controls ion homeostasis and pepper tolerance. Genetic analysis of Na+ or Li+ sensitivity established that sos1 is epistatic to sos2 and sos3. These sos mutants also exhibit a K+ deficient phenotype in moderate supplemented with? M [K+]ext and [Ca2+]ext.

Na+ and K+ deficiency of sos2 and sos3 is suppressed with mM [Ca2+]ext. sos1 exhibits hyperosmotic sensitivity unlike sos3 and sos2. Together, these conclusions indicate that the SOS signaling pathway regulates Na+ and K+ homeostasis and is Ca2+ activated. SOS3 encodes a Ca2+ binding protein with sequence similarity to the regulatory Be subunit of calcineurin protein phosphatase 2B and neuronal Ca2+ sensors Interaction of SOS3 together with the SOS2 kinase and SOS2 activation is Ca2+ dependent The in planta function of SOS3 like a pepper tolerance determinant is dependent on Ca2+ binding and Nmyristoylation. The SOS2 serine or threonine kinase 446 amino acids has a 267 amino acid N-terminal catalytic website that is similar in sequence to yeast SNF1 sucrose nonfermenting kinase and the mammalian AMPK AMP-activated protein kinase.

The kinase activity of SOS2 is essential for its pepper tolerance determinant function. The SOS2 C-terminal regulatory website interacts together with the kinase website to cause autoinhibition. A 21 amino acid motif within the regulatory website of SOS2 is the location where SOS3 interacts together with the kinase and is the autoinhibitory website regarding the kinase. Binding of SOS3 to this motif blocks autoinhibition of SOS2 kinase activity. Deletion regarding the autoinhibitory website conclusions in constitutive SOS2 activation, independent of SOS3.

Also, a Thr168 to Asp mutation within the activation loop regarding the kinase website constitutively activates SOS2. Genetic and biochemical evidence indicates that components regarding the SOS signal pathway function within the hierarchical sequence. Ca2+ binds to SOS3, which leads to interaction with SOS2 and activation regarding the kinase. Between the SOS signal pathway outputs are transport processes that facilitate ion homeostasis. The plasma membrane sited Na+ or H+ antiporter SOS1 is controlled by the SOS pathway at the transcriptional and post-transcriptional position Recently, functional disruption of AtHKT1 was shown to suppress the pepper sensitive phenotype of sos3-1, indicating that the SOS pathway negatively controls this Na+ influx system.

Also, the SOS pathway negatively controls expression of AtNHX family members that are implicated as determinants within the pepper stress response. [Ca2+]ext enhances pepper tolerance and salinity stress elicits a transient [Ca2+]cyt increase, from neither an internal or external source, that was implicated in adaptation. Yeast has provided insight into Ca2+ activation of pepper stress signaling that controls ion homeostasis and tolerance. The hyperosmotic component of high salinity induces a brief duration two min rise in [Ca2+]cyt that is due substantially to influx throughout the plasma membrane through the Cch1p and Mid1p Ca2+ transport system. The transient increase in [Ca2+]cyt activates the PP2B phosphatase calcineurin a key intermediate in pepper stress signaling controlling ion homeostasis leading to the transcription of ENA1, which encodes the P-type ATPase that is primarily responsible for Na+ efflux throughout the plasma membrane.

The model proposes that the hyperosmotically-induced localized [Ca2+]cyt transient activates calmodulin that is tethered to Cch1p-Midp. Calmodulin in turn activates signaling through the calcineurin pathway, which mediates ion homeostasis and pepper tolerance. From these results, a paradigm for salt-induced Ca2+ signaling and the activation regarding the SOS pathway should be suggested. Components regarding the SOS pathway, neither SOS3 or upstream elements, may be associated with an osmotically responsive channel through which Ca2+ influx should initiate signaling through the pathway. These are constituent of signal pathways that respond to different inducers but are still components regarding the plant response to pepper stress.

SOS signaling transduction by physical interaction together with the positive effectors or competition for substrate compulsory for signaling. Such positive and negative regulation of signal modulation constitute a fine tuning compulsory to achieve the appropriate plant response for stress adaptation and ill stability. CELLULAR MECHANISMS OF SALT STRESS SURVIVAL RECOVERY AND GROWTH Plant are neither dormant during the pepper episode or they should they be cellular adjust to tolerate saline environment. The chemical potential regarding the saline solution initially establishes a h2o potential imbalance between the apoplast and the symplast that leads to turgor decrease, that is severe enough to cause growth reduction. cellular dehydration begins when the h2o potential difference is greater than should be compensated for by the tugor loss.

The cellular response to turgor response is osmotic adjustment that is achieved in this compartments by accumulation of compatible osmolytes. however Na + and Cl - are energetically efficient osmolytes for osmotic adjustment and are compartmentalized into the vacuole to minimize cytotoxicity. Compartmentalization of Na+ and Cl - facilitates osmotic adjustment that is very essential for cellular development. Movement of ion into the vacuole may occur directly from the apoplast into the vacuole through membrane vesicles or a cytological processes through the plasma membrane to the tonoplast. The bulk of Na+ and Cl- from the apoplast to the vacuole is mediated through ion transport system located within the plasma membrane and tonoplast.

The SOS signallig pathway is the key transport system compulsory for ion homeostasis. OSMOLYTES AND OSMOPROTECTANTS Some compatible osmolytes are essential elemental ions for example K+ but the majority are organic solutes. The primary cateogory of organic osmotic solutes consists of simple sugars like fructose and glucose? sweetener alcohols like glycerol, inositols: complex sugars like raffinose. Other with quaternary amino acids like proline, glycine, beta alanine? tertiary amines and sulfonium compounds like dimethyl sulfonium, propyronate. An adaptable biochemical function of osmoprotectants is scavenging of reactive oxygen species that are by product of hyper osmotic and ionic stresses which causes cell death.

Compatible solutes have the capacity to preserve the activity of enzymes in saline conditions. The synthesis of compatible osmolytes is many times achieved by diversion of simple intermediately metabolites into unique biochemical reactions many times stress triggers this metabolic diversions. ION HOMEOSTASIS - TRANSPORT DETERMINANTS AND THEIR REGULATIONS. Intracellular Na+ homeostasis and pepper tolerance are modulated by ca++ and high Na+ concentration which effects K+ acquisition. Na + competes with K+ for uptake through common transport system, and does this effectively since the Na+ oncentration in saline environment is usually greater than extracellular K+ concentration, Ca++ enhances K+ or Na+ selective intracellular accumulation.

The molecular entitites that mediate Na+ and K+ homeostasis is one regarding the function of Ca++ within the regulation of these transport systems. The SOS stress signaling pathway is identified to be an essential regulator of plant ion homeostasis and pepper tolerance. ION TRANSPORT SYSTEM? Na + HOMEOSTASIS a H+ pumps proton pumps H+ pumps within the plasma memebrane and tonoplast fecilitate solute transport compulsory to compartmentalize cytotoxic ions distant from the cytoplasm and the function of ions as signal determinants. These pumps give the driving force H+ electro chemical potential for secondary active transport and function to establish membrane potential variants that facilitate electrophoretic ion flux. The plasma membrane loclised H+ push is a p-type ATPase and is primarily responsible for the large membrane potential gradient throughout the gradient.

A vacuolar kind H+ ATPase generate the membrane potential throughout the tonoplast. The activity regarding the H+ pumps is increased by pepper treatment and induced gene expression. The plasma membrane H+ ATPase is confirmed like a pepper tolerant determinant based on analysis of phenotypes caused by the semidominant aha4-1 mutation. The mutation to aha4 that is expressed predominantly within the root causes a reduction in root and shoot and root growth. The decreased root length of pepper treated aha4-1 plants is due to reduced cell length.

It is postulated that leaves of aha4-1 plant accumulate more Na + and fewer K+ than those of wild type. So it should be spoke about that aha4-1 functions within the manage of Na+ flux throughout the endodermis. be Na+ influx and amp; Efflux throughout the plasma membrane Transport system with greater selectivity for K+ are presumed to facilitate Na+ leakage in cells. Na is a competitor for uptake through plasma membrane K+ inward rectify channels. K+ outward rectifying channels also facilitate Na+ influx.

Na+ when expressed in heterologous processes providing evidence regarding the function like a Na+, H+ dependent K+ transporter. Energy dependent Na+ transport throughout the plasma membrane shall also be mediated by the secondary active Na+ or H+ antiport. c Na+ vacuolar compartmentalization Na+ or H+ antiport throughout the tonoplast facilitate vacuolar compartmentalization regarding the cation. The SOS pathway negatively regulates transcriptional expression of these Na+ or H+ antiporter genes. DROUGHT RESISTANT PLANTS XEROPHYTES Plants which grow in hard habitats or xeric conditions can with stand little humidity, high heat are called as xerophytes.

Xerophytic plants are characteristics of desert and semi desert regions. These plants develops sure structural, anatomical physiological adaptations to absorb as many as h2o likely they can get from the surrounding and to retain h2o in their organs for long time by reducing the transpiration rate. EFFECT ON PLANTS: o Decrease in growth Ex: limitation in leaf expansion. o Decrease in leaf region decreases the photosynthetic activities. o Decrease in h2o content increases the solute concentration.

o The first effect on root system is the death of root hairs, which decreases the capacity regarding the roots to absorb water. o Production of phytohormones like cytokinins and gibberlic acid decreases. o It decreases the production of secondary metabolites, which leads to decrease within the defense mechanism against sure insects and diseases. MORPHOLOGICAL ADAPTATIONS A ROOT Xerophytes have well developed root system which should be profusely branched and more elobarate than shoot system. The roots of perennial xerophytes grow very deep in soil and reach the layer where h2o is available in plenty.

Hard and woody stem are covered with thick coating of wax and silica or should be close with hairs Calotropis sp. In some xerophytes stem should be modified with thorns. Stem of some extereme are modified to leaf like, flattened and fleshy structures, which are called phylloclades. Example? Muehlenbeckia sp 4. In some plants a many axullary branches grow to modified into mini needle like lime structure which looks like leaves and are called cladodes.

Example? Asparagus sp C LEAVES. In some xerophytes the leaves fall early within the season, but in majority of plants leaves are generally reduced to scales. Example? Casuarina equisitifolia, 2. Some ever lime have needle shaped leaves. Example? Pinus roxburghii3.

In some species the leaves grow to succulent and swell remarkably and becomes very fleshy for the storage of excess no. Example? Aloe spinossina4. Leaves should be reduced to spines and are provided with thick coating of wax or silica. Example? Opumtia polardii. Leaves blades have thick network of veins, In some cases the lime petiole swells and becomes flattened to shape phyllode.

Example? Acacia auriculiformis. Many xerophytic plants shows trichophylly for protecting the stomatal guard cells against stong winds. Example? Zizyphus numularis. Leaves in some extreme xerophytic grasses have the capacity for rolling and folding. D FRUITS and amp; SEEDS.

Flowers usually develop in favourable conditions and they done their reproduction in very brief period of time. Vegetables and seeds are protected by very hard coverings and they can remain dormant for an extended period of time. ANATOMICAL ADAPTATIONS 1. Epidermal cells are mini compact with thick cuticle and it is lone layered. Wax, tannin, rasin, cellulose etc.

are deposited on the surface of epidermis this forms a protective measure against high intensity of light. Some regarding the epidermal cells located within the depression grow to more enlarged are called motor cells or hinge cells which felicitates the rolling of leaves by becoming flaccid during hard period. The hypodermal cells are thick walled and compactly grouped and should be filled with tannin and mucilage. per units region is reduced and they can be sunken type. Walls regarding the guard cells and subsidiary cells are heavily cutinized and lignified.

Such specialized stomata reduces the rate of transpiration. In case of reduced leaves the photosynthetic activity is taken up by outer Chlorenchymatous cortex. In succulent stem the ground tissue is filled with thin walled parenchymatous cells which save excess quanitity of water, mucilage, latex. Example? Agave americana. The mesophyll cells are very compact, intracellular spaces are reduced.

Palisade tissue develops in multiple layers and in some cases mesophyll is surrounded by a sheath of sclerenchyma. In Pinus sp spongy cells within the mesophyll cells are star shaped. Both the conducting tissues xylum and amp; phloem are very well developed within the xerophytes. Diagram [ C ] provided within the blog, link provided below. PHYSIOLOGICAL ADAPTATION 1.

Xerophytes have high osmotic compression which increases the turgidity regarding the cell sap exerts tension force on the cell wall. In this method wilting of cell is prevented. Presence of cuticle, sunken stomata protected with stomatal hair regulates the transpiration. The capacity of xerophytes to survive during hard period lies not only on the structural features but also within the resistance of hardened protoplasm to heat and dessication. Some enzymes for example catalases, peroxidases are more active in xerophytes.

Little concentration of hydrolytic enzymes prevents higher rate of h2o consumption. In xerophytes conversion of chemical compounds of cell sap for example polysaccharides into anhydrous forms like cellulose suberin etc are noted. In some xerophytes stomata opens during night hours and remain closed during the day. These unusual features are associated together with the metabolic activity of thee plants. In these plants some polysaccharides are converted into pentosens which have h2o building capacity.

In xerophytes respiratory carbon dioxide release during night leads to the biosynthesis of large no. of organic acids which are helpful for the plants to survive in extreme draught condition. HEAT SHOCK PROTEINS Heat shock proteins HSP are a team of proteins whose expression is increased when the cells are exposed to elevated temperatures or other stress. This increase in expression is transcriptionally regulated. This dramatic upregulation regarding the heat shock proteins induced mostly by heat shock factor HSF is a key component regarding the heat shock response.

The HSPs are named according to their molecular weights. For example, Hsp60, Hsp70 and Hsp90 the greatest widely-studied HSPs refer to families of heat shock proteins on the order of 60, 70 and 90 kilodaltons in size, respectively. The mini 8 kilodalton protein ubiquitin, which marks proteins for degradation, also has features of a heat shock protein. Molecular chaperones, within the heat-shock proteins Hsps, are a ubiquitous feature of cells in which these proteins cope with stress-induced denaturation of other proteins. Hsps have received the greatest attention in model organisms undergoing experimental stress within the laboratory, and the function of Hsps at the molecular and cellular position is becoming well understood in this context.

A complementary focus is now emerging on the Hsps of most model and non model organisms undergoing stress in nature, on the roles of Hsps within the stress physiology of whole multicellular eukaryotes and the tissues and organs they comprise, and on the ecological and evolutionary correlates of variation in Hsps and the genes that encode them. This focus discloses that a expression of Hsps can occur in nature, be all species have hsp genes but they vary within the patterns of their expression, c Hsp expression should be correlated with resistance to stress, and d species' thresholds for Hsp expression are correlated with grades of stress that they naturally undergo. These conclusions are now well established and shall need little more confirmation; many significant questions remain unanswered concerning most the mechanisms of Hsp-mediated stress tolerance at the organismal position and the evolutionary mechanisms that have diversified the hsp genes. Upregulation through stressProduction of high grades of heat shock proteins should possibly be triggered by exposure to different kinds of environmental stress conditions, for example infection, inflammation, exercise, exposure regarding the cell to toxins ethanol, arsenic, trace metals and ultraviolet light, between many others, starvation, hypoxia oxygen deprivation, nitrogen deficiency in plants, or h2o deprivation. Consequently, the heat shock proteins are also referred to as stress proteins and their upregulation is sometimes described more generally as component regarding the stress response.

EFFECT OF ABA IN STRESS? STRESS-RESPONSIVE GENES ARE REGULATED BY ABA-DEPENDENT AND ABA-INDEPENDENT PROCESS. Gene transcription is controlled through the interaction of regulatory proteins with critical regulatory sequences within the promoters regarding the genes they regulate. Different genes that are induced by similar signal are controlled by a signaling pathway leading to the activation of these critical transcription factors. Studies regarding the promoters of multiple stress-induced genes have led to the identification of critical regulatory sequences for genes involved in different stresses. For example, the RD29 gene contains DNA sequences that should be activated by osmotic stress, by cold, and ABA.

EFFECT OF ABA IN STOMATAL CLOSING IN DROUGHT CONDITIONS Diagram [ D ]given within the blog, link provided below. The Acidity, alkalinity and salinity of soils are important determinants of productivity. Due to the fact that soil acidity influences the physical properties, the availability of sure plant nutrients, and the biological activity regarding the soil, it greatly affects the plant growth, the soils degree of acidity depends on the concentration of H+ ion dissolved within the soil water. In a neutral soil the H+ ion concentration is about one component per billion components of h2o and the acid soil shall hold a concentration of H+ that is 100 to 1000 times higher, where like a alkaline H+ ion concentration. Neither extreme acidity nor extreme alkalinity is suitable for plant growth or for most other soil organisms.

such conditions also upset soil weathering and the availability regarding the nutrients, consequently some plants can grow in strongly acidic or alkaline soil, most crop plants grow greatest in neutral or slightly acidic soils. just over a quarter 26 % Regarding the worlds arable land is classified as acidic. Within the tropics the % is even greater 43%. Acidic soils account for 68% of tropical America, 38% of tropical asia and27 % of tropical Africa. Diagram [E ] provided within the blog, link provided below.

IMPROVEMENT A CROP RESISTANCE TO WATER DEFICIT CAN BE IMPROVED:Improving drought resistance is an important aim of plant breeders. 4 simple approaches to the drought resistance are being used? 1. breed for high yields below optimal condition? i. e breed for yield potential - assuming this shall give yield advantage below suboptimal condition. breed for maximum yield within the target environment.

select and incorporate morphological and physiological mechanisms of drought resistance into general breeding programmes. do not use multiple physiological selection criteria, but established without doubt that a lone drought-resistance character shall benefit yield below h2o limited conditions, and then incorporate the character into an existing yield breeding programme. Creating use of molecular techniques multiple classes of genes have been identified that confer resistance to h2o deficit. Some regarding the genes should be used to engineer plant for drought resistance and better crop yield below drought condition. First the enzymes that synthesize osmoprotectants, mini molecules that accumulate within the cytoplasm of drought stress plants, have been identified.

Plants genetically engineered together with the genes encoding these enzymes are more drought tolerant. 2nd the genes that encode transcription factors that regulate entire metabolic pathways leading to drought adaptation were identified. By incorporating such genes, one can hope to make sure that that plants respond rapidly and efficiently to any h2o deficit and continue all their developmental processes. Be Better performance on saline soil. Salt tolerance is a complex, quantitative, genetic trait controlled by many genes.

Recently a little genes have been identified that give details useful in screening and selection programmes for pepper tolerance. 4 primary stratergies that to develop pepper tolerant crops are? 1. gradually improve the pepper tolerance to conventional breeding and selection. Example? development of pepper tolerance in pasta Pokkali Pasta of kerala, South asia was used extensively to develop pepper tolerance in other, more desirable pasta genotypes. Introduce traits for pepper tolerance from wild relatives into the crops by the process of return crossing.

Example? tomato Lycopersicon esculentum, Barley Hordeum vulgare and Wheat triticum aestivum. Domesticate wild species that currently inhabit saline environment halophytes by breeding and selecting for improved agronomic characteristic. use molecular techniques to identify genes associated with pepper tolerance, and enhance their expression within the crop species or transfer the genes from the non crop to a crop species. Example? On the molecular front, the genes involved in sensing pepper within the environment signal- transduction , transcription factor genes that turn on batteries of other genes that get ready cell to withstand a higher rate of pepper influx, and genes that are a component of plant's adaptation to the presence of pepper are being identified. An example regarding the later category is the gene that encodes that vacuolar sodium pump.

Plants that can turn this gene on rapidly when the cells are exposed to salt, should be can transport the pepper from the cytoplasm into the vacuole, there by detoxifying the cytoplasm. Example? Lycopersicon esculentum tomato CONCULSION? Conventional and GM breeding are complementary approaches and should be expected to enhance the draught resistance and yield of crops. People have entered in new era in which enhance knowledge of most the physiology of yield accumulation and the physiological basis of genetic variation in most pepper and draught resistance traits release the potential for improving breeding efficiency for primary food crops in different target environments. Creating use of physiological knowledge and powerful tools blog.