Transgenic Approach for Abiotic Stress Tolerance
Dec 13, 2015
Transgenic Approach for Abiotic Stress Tolerance
Characteristics features of plant stress protein
No. Stress Protein Induction agent Characteristics features
1 HSP (heat shock protein)
Mostly by high temperature stress, also by water stress, salt stress, low temperature stress, in some cases also by abscisic acid
Classified aslow molecular weight HSPs and high molecular weight HSPs, highly conserved amino acid sequence, nucleotide sequence of the corresponding genes is also conserved, stress-inducible of hs genes governed by HSEs (heat shock elements), selected HSPs are shown to act as chaperons
2 Osmotic stress proteins such as WSPs (water stress proteins) and SSPs (salt stress proteins)
Mostly by low water availability and salt stress, also induced by ABA
Varied molecular weights and cellular locations, these proteins are mostly the enzymes involved in diverse functions such as production of different osmolytes, protein degradation, signal transduction events, gene regulation and transport. Roles of some WSPs is not well defined (i.e. such as for dehydrins, late embryogenesis, abundant proteins)
Characteristics features of plant stress protein
No. Stress Protein Induction agent Characteristics features
3 ANPs (anaerobic proteins)
Mostly by anaerobic stress (caused by flooding or submergence stress)
Discovered initially in maize and later shown tin o be universally present, most of the ANPs have been shown to be the enzymes of the fermentative or the glycolytic pathway, most genes encoding ANPs contain . AREs (anaerobic response elements) in their promoters
4 Cold stress proteins such as COR (cold-regulated proteins)
Mostly by low temperature stress, also by osmotic, oxidative stress and ABA
Conserved proteins of varied sizes and functions, most COR genes contain specific nucleotide sequence that stimulate transcription in response to low temperature
Stress Induced gene expression
1.Genes encoding proteins with known enzymatic or structural functions
2.Protein with as yet unknown functions3.Regulatory protein
Single action gene
Osmoprotectant genes: Proline, Gly/Bet, Sugar polyolsDetoxifying genes: SOD, PXLate embryogenesis abundant genes: LEATransporter genes: Aquapurin, Ion transporterMultifunctional genes for lipid biosynthesis:GPAT
(glycerol-3-phosphate acyltransferase), FAD7 (Fatty acid desaturase)
Heat shock genes: HS
Regulatory Genes
Transcription factors genes CBF/DREB, ABF, HSF, bZIP, MYC/MYB
Signal transduction genesa. Osmocensors (AtHK-1)b. Phospholipid cleaving enzymes (PLD)c. Second messengers (Ptd-OH, ROS)d. MAP kinases, Ca+ censor (SOS-3)e. Calcium –dependent protein kinases (CDPKs)
Abiotic stress tolerance1.Increase cellular level of osmotically-active
solute (proline, glycinebetaine, mannitol, trehalose, fructans)
2.Increase levels of osmolytes3.It is mediated by a number of biochemical
reactions /physiological processes (a multi genic trait)
4.It can be augmented by pyramiding different stress-responsive genes
Osmolyte and Compatible Solutes
Gene Protein Source Cellular role(s)
gpat Glycerol 3-phosphate acyltransferase
Cucurbita maxima, Arabidopsis thaliana
Fatty acid unsaturation
mtlD Mannitol 1-phosphate dehydrogenase
Eschericia coli Manitol biosynthesis
sod Superoxide dismutase
Nicotiana plumbaginifolia
Superoxide dismutase
Bet-B Betaine aldehyde dehydrogenase
Eschericia coli Glycinebetaine dismutase
Gene Protein Source Cellular role(s)
Bet-A Choline dehydrogenase
Eschericia coli Glycinebetaine dismutase
p5cs Pyroline 5-carboxylase synthase
V. aconitifolia Proline biosynthesis
Sac-B Levan sucrase Baccilus subtilis Fructan biosynthesis
Hva-1 LEA protein Hordeum vulgare
-
Tps-1 Trehalose 6-phosphate synthase
Arabidopsis thaliana
Trehalose biosynthesis
Osmolyte and Compatible Solutes
Gene Protein Source Cellular role(s)
Cod-A/Cod-1/Cox Choline oxidase Arthrobacter globiformis
Glycinebetaine biosynthesis
afp Antifreeze protein (AFP)
Synthetic Inhibit ice growth and recrystallization
Imt-1 Myo-inositol-o-methyl transferase
Messembryanthemum crystallinum
D-ononitol biosynthesis
BADH Betaine dehydrogenase
Spinach Glycinebetaine byosynthesis
Osmolyte and Compatible Solutes
Gene Protein Source Cellular role(s)
Ect-A, Ect-B, Ect-C
L-2,4-diaminobutyric acetyltransferaseL-2,4-diaminobutyric acid trans-aminaseL-ectoine synthase
Halomonas elongata
Ectoyne
Ots-A, Ots-B Trehalose-6-P synthaseTrehalose-6-P phosphatase
Eschericia coli Trehalose
Osmolyte and Compatible Solutes
Gene Protein Source Cellular role(s)
Pro-DH Proline dehydrogenase
Arabidopsis thaliana
Proline
HAL-3 FMN-binding protein
Saccharomyces cerevisae
Na+/K+ homeostasis
Osmolyte and Compatible Solutes
Gene Protein Source Cellular role(s)
AtNHX-1 Vacuolar Na+/H+ antiporter
Arabidopsis thaliana
Na+ vacuolar sequestration
AtSOS-1 Plasma membrane Na+/H+ antiporter
Arabidopsis thaliana
Na+ extrusion
AVP-1 Vacuolar H+-pyrophosphatase
Arabidopsis thaliana
Vacuolar acidification
HAL-1 K+/Na+ transport regulation
Saccharomyces cerevisiae
K+/Na+ homeostasis
Ion Transporters and Ion Homeostasis
Gene Protein Source Cellular role(s)
MnSOD Superoxide dismutase
Saccharomyces cerevisiae
Reduction of O2 content
Gly-1 Glyoxylase Brassica juncea S-D-lactoylglutathione
TPX-2 Peroxidase Nicotiana tabacum
Change cell properties
GST
GPX
Glutathione S-transferaseGlutathione peroxidase
Nicotiana tabacumNicotiana tabacum
ROS scavenging
Redox Proteins
Gene Protein Source Cellular role(s)
DREB-1A Transcription factor
Arabidopsis thaliana
Improved gene expression
Cnb-1 Calcineurin Saccharomyces cerevisiae
Improved Ca++ signaling
OsCDPK-7 Protein kinase Oryza sativa Improved gene expression
Transcription and signal transduction factors
Gene Protein Source Cellular role(s)
DnaK Heat shock protein
A. halophytica
Protein stabilization
Apo-Inv Apoplastic yeast-derived invertase
Saccharomyces cerevisiae
Sucrose synthesis
Mischelineous
Perspective in Abiotic Stress Tolerance
1. Abiotic stress elicit multigenic responses within the plant cells. The tolerance to different abiotic stress is contributed by a range of different biochemical/physiological mechanism
2. Only a limited number of plant genes with a definite function have been identified, cloned and characterized
3. Changing levels of transcription factors can alter the levels of several genes at the same time
4. The transgenics raised far for enhancing tolerance to abiotic stress have been achieved through employing strong constitutive promoters, for driving expression of the transgenes. Promoters which are induced by different abiotic stress including high temperature stress, anaerobic stress, salt stress and water stress have poor strength of expression when compared to constitutively expression promoter