genetic factors affecting abiotic stress tolerance
TRANSCRIPT
GENETIC FACTORS AFFECTING ABIOTIC STRESS TOLERANCE
Prepared by,
BHAVYASREE R K
2016800802
Dept. Of Genetics and Plant Breeding
Introduction
• Crop yield reduction and climatic change• Beneficial loci for productivity : in challenging
environment• Abiotic stress refers to suboptimal climatic
and/or edaphic conditions that adversely affect cellular homeostasis and that ultimately impair growth and fitness (Michelbart et al 2015)
• Tolerence or avoidance through acclimation and adaptation :evolved through natural selection
• Gene and QTL mapping: genetic cause behind biological mechanisms
Flooding
• Reduced energy owing to lower photosynthesis rate and/or low O2 levels
• Rice – SUBMERGENCE1 (SUB1)- Indian landrace Dhalputtia (FR13A)– SNORKEL genes:SK1 and SK2- Thai deepwater accession
(Japonica) C9285
• survive more than 2 weeks of complete submergence• The genes responsive for Ethylene responsive transcription
factors– SUB1 :Ethylene-promoted inhibition of GA-mediated elongation
:energy conservation– SK1 and SK2 : Ethylene- promoted, GA-mediated elongation of
stem internodes
Drought
• DRO1 : Rice from a tolerant genotype
– DRO1, DEEPER ROOTING1
– Unknown gene product
– Enhanced deep rooting; Auxin-regulated asymmetric root growth
Salinity
• The genes codes for Na+ transporters• HKT1;5-A at the Nax2 locus
– Triticum turgidum ssp. durum from Triticum monococcum– Root Na+ exclusion from xylem vessels
• TaHKT1;5– Triticum aestivum from T. aestivum D genome (origin
Aegilops tauschii– Higher K+/Na+ in expanding and young leaves
• HKT1;5 – O. sativa ssp. japonica from Tolerant O. sativa ssp. indica– Shoot K+/Na+ homeostasis
Ion toxicity
• High Al3+
– Root Al3+-activated transporter genes : detoxification or compartmentalisation
– SbMATE at the AltSB locus : Sorghum bicolor (Citrus chelation)
– MATE1 in Zea mays (Citrus chelation)
– ALMT in T. aestivum (Malate chelation)
– NRAT1 in O. sativa(compartmentalization)
• High B
– Root B efflux transporter
– Restricts net B accumulation
– Bot1 in Hordeum vulgare
– Bot-B5b in Triticum aestivum
Ion toxicity
Ion deficiency
• Low Pi– PSTOL1 at the Pup1 locus in O. sativa– From African rice– Protein kinase– Enhanced crown root development
for improved Pi acquisition
• Low Fe3+ and Zn2+– NAM-B1 in T. turgidum ssp. durum
• NAC Transcription factors• Accelerates senescence and nutrient
remobilization to grain
Low and sub-freezing temperatures
• VRN1 at the FR1 locus – T. aestivum & H. vulgare
– MADS box TF
– Regulation of vernalization; low-temperature-induced CBF and regulation activation; freezing tolerance
• CBFs at the FR2 locus – T. aestivum & H. vulgare
– CBFs (TFs)
– CBF copy number-dependent expression and regulonactivation; freezing tolerance
•
High temperature
• Rapid alterations in gene expression, increases in heat shock protein (HSP) levels, modification of membranes, alterations in the cytoskeleton and management of oxidative stress
• Wheat– Alien introgression from wild relative Leymus racemosus
provided heat tolerance
• Heat & drought tolerant rice :N22 (aus ssp.) – QTLs : high levels of HSPs in anthers, spikelets and flag leaves
• Escape strategy :QTLs from Oryza officinalis– avoid heat-induced spikelet sterility – promoting dehiscence and fertilization in the cooler early
mornings
THANK YOU…