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…